LinuxLists.cc - [PATCH v3] TLB flush optimization

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Subject: [PATCH v3 2/7] x86/flush_tlb: try flush_tlb_single one by one in flush_tlb_range

x86 has no flush_tlb_range support in instruction level. Currently the
flush_tlb_range just implemented by flushing all page table. That is not
the best solution for all scenarios. In fact, if we just use 'invlpg' to
flush few lines from TLB, we can get the performance gain from later
remain TLB lines accessing.

But the 'invlpg' instruction costs much of time. Its execution time can
compete with cr3 rewriting, and even a bit more on SNB CPU.

So, on a 512 4KB TLB entries CPU, the balance points is at:
(512 - X) * 100ns(assumed TLB refill cost) =
X(TLB flush entries) * 100ns(assumed invlpg cost)

Here, X is 256, that is 1/2 of 512 entries.

But with the mysterious CPU pre-fetcher and page miss handler Unit, the
assumed TLB refill cost is far lower then 100ns in sequential access. And
2 HT siblings in one core makes the memory access more faster if they are
accessing the same memory. So, in the patch, I just do the change when
the target entries is less than 1/16 of whole active tlb entries.
Actually, I have no data support for the percentage '1/16', so any
suggestions are welcomed.

As to hugetlb, guess due to smaller page table, and smaller active TLB
entries, I didn't see benefit via my benchmark, so no optimizing now.

My macro benchmark show in ideal scenarios, the performance improves 70
percent in reading. And in worst scenario, the reading/writing
performance is similar with unpatched 3.4-rc4 kernel.

Here is the reading data on my 2P * 4cores *HT NHM EP machine, with THP
'always':

multi thread testing, '-t' paramter is thread number:
with patch unpatched 3.4-rc4
./mprotect -t 1 14ns 24ns
./mprotect -t 2 13ns 22ns
./mprotect -t 4 12ns 19ns
./mprotect -t 8 14ns 16ns
./mprotect -t 16 28ns 26ns
./mprotect -t 32 54ns 51ns
./mprotect -t 128 200ns 199ns

Single process with sequencial flushing and memory accessing:

with patch unpatched 3.4-rc4
./mprotect 7ns 11ns
./mprotect -p 4096 -l 8 -n 10240
21ns 21ns

I also tried other benchmarks on Intel core2/NHM/SNB EP and NHM EX machine.
No clear performance change on specjbb2005 with openjdk, and oltp reading.

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/include/asm/paravirt.h | 5 +-
arch/x86/include/asm/paravirt_types.h | 3 +-
arch/x86/include/asm/tlbflush.h | 19 +++----
arch/x86/include/asm/uv/uv.h | 5 +-
arch/x86/mm/tlb.c | 97 +++++++++++++++++++++++++++------
arch/x86/platform/uv/tlb_uv.c | 6 +-
arch/x86/xen/mmu.c | 9 ++--
include/trace/events/xen.h | 12 +++--
8 files changed, 113 insertions(+), 43 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index aa0f913..03da4ab 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -397,9 +397,10 @@ static inline void __flush_tlb_single(unsigned long addr)

static inline void flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm,
- unsigned long va)
+ unsigned long start,
+ unsigned long end)
{
- PVOP_VCALL3(pv_mmu_ops.flush_tlb_others, cpumask, mm, va);
+ PVOP_VCALL4(pv_mmu_ops.flush_tlb_others, cpumask, mm, start, end);
}

static inline int paravirt_pgd_alloc(struct mm_struct *mm)
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 8e8b9a4..600a5fcac9 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -250,7 +250,8 @@ struct pv_mmu_ops {
void (*flush_tlb_single)(unsigned long addr);
void (*flush_tlb_others)(const struct cpumask *cpus,
struct mm_struct *mm,
- unsigned long va);
+ unsigned long start,
+ unsigned long end);

/* Hooks for allocating and freeing a pagetable top-level */
int (*pgd_alloc)(struct mm_struct *mm);
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index c0e108e..ec30dfb 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -77,7 +77,7 @@ static inline void __flush_tlb_one(unsigned long addr)
* - flush_tlb_page(vma, vmaddr) flushes one page
* - flush_tlb_range(vma, start, end) flushes a range of pages
* - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
- * - flush_tlb_others(cpumask, mm, va) flushes TLBs on other cpus
+ * - flush_tlb_others(cpumask, mm, start, end) flushes TLBs on other cpus
*
* ..but the i386 has somewhat limited tlb flushing capabilities,
* and page-granular flushes are available only on i486 and up.
@@ -115,7 +115,8 @@ static inline void flush_tlb_range(struct vm_area_struct *vma,

static inline void native_flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm,
- unsigned long va)
+ unsigned long start,
+ unsigned long end)
{
}

@@ -133,17 +134,14 @@ extern void flush_tlb_all(void);
extern void flush_tlb_current_task(void);
extern void flush_tlb_mm(struct mm_struct *);
extern void flush_tlb_page(struct vm_area_struct *, unsigned long);
+extern void flush_tlb_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end);

#define flush_tlb() flush_tlb_current_task()

-static inline void flush_tlb_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
-{
- flush_tlb_mm(vma->vm_mm);
-}
-
void native_flush_tlb_others(const struct cpumask *cpumask,
- struct mm_struct *mm, unsigned long va);
+ struct mm_struct *mm,
+ unsigned long start, unsigned long end);

#define TLBSTATE_OK 1
#define TLBSTATE_LAZY 2
@@ -163,7 +161,8 @@ static inline void reset_lazy_tlbstate(void)
#endif /* SMP */

#ifndef CONFIG_PARAVIRT
-#define flush_tlb_others(mask, mm, va) native_flush_tlb_others(mask, mm, va)
+#define flush_tlb_others(mask, mm, start, end) \
+ native_flush_tlb_others(mask, mm, start, end)
#endif

static inline void flush_tlb_kernel_range(unsigned long start,
diff --git a/arch/x86/include/asm/uv/uv.h b/arch/x86/include/asm/uv/uv.h
index 3bb9491..b47c2a8 100644
--- a/arch/x86/include/asm/uv/uv.h
+++ b/arch/x86/include/asm/uv/uv.h
@@ -15,7 +15,8 @@ extern void uv_nmi_init(void);
extern void uv_system_init(void);
extern const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm,
- unsigned long va,
+ unsigned long start,
+ unsigned end,
unsigned int cpu);

#else /* X86_UV */
@@ -26,7 +27,7 @@ static inline void uv_cpu_init(void) { }
static inline void uv_system_init(void) { }
static inline const struct cpumask *
uv_flush_tlb_others(const struct cpumask *cpumask, struct mm_struct *mm,
- unsigned long va, unsigned int cpu)
+ unsigned long start, unsigned long end, unsigned int cpu)
{ return cpumask; }

#endif /* X86_UV */
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index d6c0418..c4e694d 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -41,7 +41,8 @@ DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate)
union smp_flush_state {
struct {
struct mm_struct *flush_mm;
- unsigned long flush_va;
+ unsigned long flush_start;
+ unsigned long flush_end;
raw_spinlock_t tlbstate_lock;
DECLARE_BITMAP(flush_cpumask, NR_CPUS);
};
@@ -154,10 +155,19 @@ void smp_invalidate_interrupt(struct pt_regs *regs)

if (f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
- if (f->flush_va == TLB_FLUSH_ALL)
+ if (f->flush_start == TLB_FLUSH_ALL
+ || !cpu_has_invlpg)
local_flush_tlb();
- else
- __flush_tlb_one(f->flush_va);
+ else if (!f->flush_end)
+ __flush_tlb_single(f->flush_start);
+ else {
+ unsigned long addr;
+ addr = f->flush_start;
+ while (addr <= f->flush_end) {
+ __flush_tlb_single(addr);
+ addr += PAGE_SIZE;
+ }
+ }
} else
leave_mm(cpu);
}
@@ -170,7 +180,8 @@ out:
}

static void flush_tlb_others_ipi(const struct cpumask *cpumask,
- struct mm_struct *mm, unsigned long va)
+ struct mm_struct *mm, unsigned long start,
+ unsigned long end)
{
unsigned int sender;
union smp_flush_state *f;
@@ -183,7 +194,8 @@ static void flush_tlb_others_ipi(const struct cpumask *cpumask,
raw_spin_lock(&f->tlbstate_lock);

f->flush_mm = mm;
- f->flush_va = va;
+ f->flush_start = start;
+ f->flush_end = end;
if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(smp_processor_id()))) {
/*
* We have to send the IPI only to
@@ -197,24 +209,26 @@ static void flush_tlb_others_ipi(const struct cpumask *cpumask,
}

f->flush_mm = NULL;
- f->flush_va = 0;
+ f->flush_start = 0;
+ f->flush_end = 0;
if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS)
raw_spin_unlock(&f->tlbstate_lock);
}

void native_flush_tlb_others(const struct cpumask *cpumask,
- struct mm_struct *mm, unsigned long va)
+ struct mm_struct *mm, unsigned long start,
+ unsigned long end)
{
if (is_uv_system()) {
unsigned int cpu;

cpu = smp_processor_id();
- cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
+ cpumask = uv_flush_tlb_others(cpumask, mm, start, end, cpu);
if (cpumask)
- flush_tlb_others_ipi(cpumask, mm, va);
+ flush_tlb_others_ipi(cpumask, mm, start, end);
return;
}
- flush_tlb_others_ipi(cpumask, mm, va);
+ flush_tlb_others_ipi(cpumask, mm, start, end);
}

static void __cpuinit calculate_tlb_offset(void)
@@ -280,7 +294,7 @@ void flush_tlb_current_task(void)

local_flush_tlb();
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL);
+ flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL, 0UL);
preempt_enable();
}

@@ -295,12 +309,63 @@ void flush_tlb_mm(struct mm_struct *mm)
leave_mm(smp_processor_id());
}
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL);
+ flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL, 0UL);
+
+ preempt_enable();
+}
+
+#define FLUSHALL_BAR 16
+
+void flush_tlb_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end)
+{
+ struct mm_struct *mm;
+
+ if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB) {
+ flush_tlb_mm(vma->vm_mm);
+ return;
+ }
+
+ preempt_disable();
+ mm = vma->vm_mm;
+ if (current->active_mm == mm) {
+ if (current->mm) {
+ unsigned long addr, vmflag = vma->vm_flags;
+ unsigned act_entries, tlb_entries = 0;
+
+ if (vmflag & VM_EXEC)
+ tlb_entries = tlb_lli_4k[ENTRIES];
+ else
+ tlb_entries = tlb_lld_4k[ENTRIES];
+
+ act_entries = tlb_entries > mm->total_vm ?
+ mm->total_vm : tlb_entries;

+ if ((end - start)/PAGE_SIZE > act_entries/FLUSHALL_BAR)
+ local_flush_tlb();
+ else {
+ for (addr = start; addr <= end;
+ addr += PAGE_SIZE)
+ __flush_tlb_single(addr);
+
+ if (cpumask_any_but(mm_cpumask(mm),
+ smp_processor_id()) < nr_cpu_ids)
+ flush_tlb_others(mm_cpumask(mm), mm,
+ start, end);
+ preempt_enable();
+ return;
+ }
+ } else {
+ leave_mm(smp_processor_id());
+ }
+ }
+ if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
+ flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL, 0UL);
preempt_enable();
}

-void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
+
+void flush_tlb_page(struct vm_area_struct *vma, unsigned long start)
{
struct mm_struct *mm = vma->vm_mm;

@@ -308,13 +373,13 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)

if (current->active_mm == mm) {
if (current->mm)
- __flush_tlb_one(va);
+ __flush_tlb_one(start);
else
leave_mm(smp_processor_id());
}

if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, va);
+ flush_tlb_others(mm_cpumask(mm), mm, start, 0UL);

preempt_enable();
}
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 3ae0e61..0df5ad2 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1068,8 +1068,8 @@ static int set_distrib_bits(struct cpumask *flush_mask, struct bau_control *bcp,
* done. The returned pointer is valid till preemption is re-enabled.
*/
const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,
- struct mm_struct *mm, unsigned long va,
- unsigned int cpu)
+ struct mm_struct *mm, unsigned long start,
+ unsigned end, unsigned int cpu)
{
int locals = 0;
int remotes = 0;
@@ -1112,7 +1112,7 @@ const struct cpumask *uv_flush_tlb_others(const struct cpumask *cpumask,

record_send_statistics(stat, locals, hubs, remotes, bau_desc);

- bau_desc->payload.address = va;
+ bau_desc->payload.address = start;
bau_desc->payload.sending_cpu = cpu;
/*
* uv_flush_send_and_wait returns 0 if all cpu's were messaged,
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index b8e2794..75bab52 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1239,7 +1239,8 @@ static void xen_flush_tlb_single(unsigned long addr)
}

static void xen_flush_tlb_others(const struct cpumask *cpus,
- struct mm_struct *mm, unsigned long va)
+ struct mm_struct *mm, unsigned long start,
+ unsigned long end)
{
struct {
struct mmuext_op op;
@@ -1251,7 +1252,7 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
} *args;
struct multicall_space mcs;

- trace_xen_mmu_flush_tlb_others(cpus, mm, va);
+ trace_xen_mmu_flush_tlb_others(cpus, mm, start, end);

if (cpumask_empty(cpus))
return; /* nothing to do */
@@ -1264,11 +1265,11 @@ static void xen_flush_tlb_others(const struct cpumask *cpus,
cpumask_and(to_cpumask(args->mask), cpus, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask));

- if (va == TLB_FLUSH_ALL) {
+ if (start == TLB_FLUSH_ALL) {
args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
} else {
args->op.cmd = MMUEXT_INVLPG_MULTI;
- args->op.arg1.linear_addr = va;
+ args->op.arg1.linear_addr = start;
}

MULTI_mmuext_op(mcs.mc, &args->op, 1, NULL, DOMID_SELF);
diff --git a/include/trace/events/xen.h b/include/trace/events/xen.h
index 92f1a79..15ba03b 100644
--- a/include/trace/events/xen.h
+++ b/include/trace/events/xen.h
@@ -397,18 +397,20 @@ TRACE_EVENT(xen_mmu_flush_tlb_single,

TRACE_EVENT(xen_mmu_flush_tlb_others,
TP_PROTO(const struct cpumask *cpus, struct mm_struct *mm,
- unsigned long addr),
- TP_ARGS(cpus, mm, addr),
+ unsigned long addr, unsigned long end),
+ TP_ARGS(cpus, mm, addr, end),
TP_STRUCT__entry(
__field(unsigned, ncpus)
__field(struct mm_struct *, mm)
__field(unsigned long, addr)
+ __field(unsigned long, end)
),
TP_fast_assign(__entry->ncpus = cpumask_weight(cpus);
__entry->mm = mm;
- __entry->addr = addr),
- TP_printk("ncpus %d mm %p addr %lx",
- __entry->ncpus, __entry->mm, __entry->addr)
+ __entry->addr = addr,
+ __entry->end = end),
+ TP_printk("ncpus %d mm %p addr %lx, end %lx",
+ __entry->ncpus, __entry->mm, __entry->addr, __entry->end)
);

TRACE_EVENT(xen_mmu_write_cr3,
--
1.7.5.4

2012-05-08 14:05:33

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Subject: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

Testing show different CPU type(micro architectures and NUMA mode) has
different balance points between the TLB flush all and multiple invlpg.
And there maybe has cases the tlb flush change has no any help.

This patch give a interface to let x86 vendor developers have a chance
to set different factors for different CPU type.

like some machine in my hands, balance points is 16 entries on Romely-EP;
while it is at 8 entries on Bloomfield NHM-EP; but on model 15 core2 Xeon
using invlpg has nothing help.

For untested machine, no optimization now.

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/include/asm/processor.h | 2 ++
arch/x86/kernel/cpu/common.c | 13 +++++++++++--
arch/x86/kernel/cpu/intel.c | 30 ++++++++++++++++++++++++++++++
arch/x86/mm/tlb.c | 8 ++++----
4 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 797faca..6a7e9c3 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -72,6 +72,8 @@ extern u16 __read_mostly tlb_lli_4m[NR_INFO];
extern u16 __read_mostly tlb_lld_4k[NR_INFO];
extern u16 __read_mostly tlb_lld_2m[NR_INFO];
extern u16 __read_mostly tlb_lld_4m[NR_INFO];
+extern u16 __read_mostly tlb_flushall_factor;
+
/*
* CPU type and hardware bug flags. Kept separately for each CPU.
* Members of this structure are referenced in head.S, so think twice
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 0152082..3e2e310 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -459,16 +459,25 @@ u16 __read_mostly tlb_lld_4k[NR_INFO];
u16 __read_mostly tlb_lld_2m[NR_INFO];
u16 __read_mostly tlb_lld_4m[NR_INFO];

+/*
+ * tlb_flushall_factor shows the balance point in replacing cr3 write with
+ * multiple 'invlpg'. Different CPU type has different this value, which
+ * get from a macro benchmark named mproctect.c that published in lkml.
+ */
+u16 __read_mostly tlb_flushall_factor;
+
void __cpuinit cpu_detect_tlb(struct cpuinfo_x86 *c)
{
if (c->x86_vendor == X86_VENDOR_INTEL)
intel_cpu_detect_tlb(c);

printk(KERN_INFO "Last level iTLB entries: 4KB %d, 2MB %d, 4MB %d\n" \
- "Last level dTLB entries: 4KB %d, 2MB %d, 4MB %d\n",
+ "Last level dTLB entries: 4KB %d, 2MB %d, 4MB %d\n" \
+ "tlb_flushall_factor is 1/%d\n",
tlb_lli_4k[ENTRIES], tlb_lli_2m[ENTRIES],
tlb_lli_4m[ENTRIES], tlb_lld_4k[ENTRIES],
- tlb_lld_2m[ENTRIES], tlb_lld_4m[ENTRIES]);
+ tlb_lld_2m[ENTRIES], tlb_lld_4m[ENTRIES],
+ tlb_flushall_factor);
}

void __cpuinit detect_ht(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 86e6131..42480c6 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -610,6 +610,35 @@ void intel_tlb_lookup(const unsigned char desc)
}
}

+void intel_tlb_flushall_factor_set(struct cpuinfo_x86 *c)
+{
+ switch (c->x86_model) {
+ case 15: /* original 65 nm celeron/pentium/core2/xeon, "Merom"/"Conroe" */
+ tlb_flushall_factor = 0;
+ break;
+ case 26: /* 45 nm nehalem, "Bloomfield" */
+ case 30: /* 45 nm nehalem, "Lynnfield" */
+ case 37: /* 32 nm nehalem, "Clarkdale" */
+ case 44: /* 32 nm nehalem, "Gulftown" */
+ case 46: /* 45 nm nehalem-ex, "Beckton" */
+ tlb_flushall_factor = 64;
+ break;
+ case 42: /* SandyBridge */
+ case 45: /* SandyBridge, "Romely-EP" */
+ tlb_flushall_factor = 32;
+ break;
+ case 28: /* Atom */
+ case 47: /* 32 nm Xeon E7 */
+ case 14: /* 65 nm core solo/duo, "Yonah" */
+ case 22: /* single-core 65 nm celeron/core2solo "Merom-L"/"Conroe-L" */
+ case 23: /* current 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
+ case 29: /* six-core 45 nm xeon "Dunnington" */
+
+ default:
+ tlb_flushall_factor = 0;
+ }
+}
+
void intel_cpu_detect_tlb(struct cpuinfo_x86 *c)
{
int i, j, n;
@@ -630,6 +659,7 @@ void intel_cpu_detect_tlb(struct cpuinfo_x86 *c)
for (j = 1 ; j < 16 ; j++)
intel_tlb_lookup(desc[j]);
}
+ intel_tlb_flushall_factor_set(c);
}

static const struct cpu_dev __cpuinitconst intel_cpu_dev = {
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 4f709e6..91896dc 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -314,8 +314,6 @@ void flush_tlb_mm(struct mm_struct *mm)
preempt_enable();
}

-#define FLUSHALL_BAR 16
-
static inline int has_large_page(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
@@ -343,7 +341,8 @@ void flush_tlb_range(struct vm_area_struct *vma,
{
struct mm_struct *mm;

- if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB) {
+ if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
+ || !tlb_flushall_factor) {
flush_all:
flush_tlb_mm(vma->vm_mm);
return;
@@ -364,7 +363,8 @@ flush_all:
act_entries = tlb_entries > mm->total_vm ?
mm->total_vm : tlb_entries;

- if ((end - start)/PAGE_SIZE > act_entries/FLUSHALL_BAR)
+ if ((end - start)/PAGE_SIZE >
+ act_entries/tlb_flushall_factor)
local_flush_tlb();
else {
if (has_large_page(mm, start, end)) {
--
1.7.5.4

2012-05-08 14:05:40

[permalink] [raw]

Subject: [PATCH v3 5/7] x86/tlb: remove comments for tlb_flush_range implement suggestion

Thanks to this comments that inspired me using invlpg to replace cr3
rewrite.
Now, it is time to remove from code to avoid reader confusing.

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/include/asm/tlbflush.h | 4 ----
1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index ec30dfb..51f8b1c 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -81,10 +81,6 @@ static inline void __flush_tlb_one(unsigned long addr)
*
* ..but the i386 has somewhat limited tlb flushing capabilities,
* and page-granular flushes are available only on i486 and up.
- *
- * x86-64 can only flush individual pages or full VMs. For a range flush
- * we always do the full VM. Might be worth trying if for a small
- * range a few INVLPGs in a row are a win.
*/

#ifndef CONFIG_SMP
--
1.7.5.4

2012-05-08 14:05:50

[permalink] [raw]

Subject: [PATCH v3 3/7] x86/tlb: fall back to flush all when meet a THP large page

We don't need to flush large pages by PAGE_SIZE step, that just waste
time. and actually, large page don't need 'invlpg' optimizing according
to our macro benchmark. So, just flush whole TLB is enough for them.

The following result is tested on a 2CPU * 4cores * 2HT NHM EP machine,
with THP 'always' setting.

Multi-thread testing, '-t' paramter is thread number:
without this patch with this patch
./mprotect -t 1 14ns 13ns
./mprotect -t 2 13ns 13ns
./mprotect -t 4 12ns 11ns
./mprotect -t 8 14ns 10ns
./mprotect -t 16 28ns 28ns
./mprotect -t 32 54ns 52ns
./mprotect -t 128 200ns 200ns

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/mm/tlb.c | 27 +++++++++++++++++++++++++++
1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index c4e694d..4f709e6 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -316,12 +316,35 @@ void flush_tlb_mm(struct mm_struct *mm)

#define FLUSHALL_BAR 16

+static inline int has_large_page(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
+{
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ unsigned long addr;
+ for (addr = start; addr <= end; addr += HPAGE_SIZE) {
+ pgd = pgd_offset(mm, addr);
+ if (likely(!pgd_none(*pgd))) {
+ pud = pud_offset(pgd, addr);
+ if (likely(!pud_none(*pud))) {
+ pmd = pmd_offset(pud, addr);
+ if (likely(!pmd_none(*pmd)))
+ if (pmd_large(*pmd))
+ return 1;
+ }
+ }
+ }
+ return 0;
+}
+
void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
struct mm_struct *mm;

if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB) {
+flush_all:
flush_tlb_mm(vma->vm_mm);
return;
}
@@ -344,6 +367,10 @@ void flush_tlb_range(struct vm_area_struct *vma,
if ((end - start)/PAGE_SIZE > act_entries/FLUSHALL_BAR)
local_flush_tlb();
else {
+ if (has_large_page(mm, start, end)) {
+ preempt_enable();
+ goto flush_all;
+ }
for (addr = start; addr <= end;
addr += PAGE_SIZE)
__flush_tlb_single(addr);
--
1.7.5.4

2012-05-08 14:05:59

[permalink] [raw]

Subject: [PATCH v3 6/7] x86/tlb: optimizing flush_tlb_mm

Not every flush_tlb_mm execution moment is really need to evacuate all
TLB entries, like in munmap, just few 'invlpg' is better for whole
process performance, since it leaves most of TLB entries for later
accessing.

This patch is changing flush_tlb_mm(mm) to flush_tlb_mm(mm, start, end)
in cases.

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/include/asm/tlb.h | 2 +-
arch/x86/include/asm/tlbflush.h | 5 ++-
arch/x86/mm/pgtable.c | 2 +-
arch/x86/mm/tlb.c | 65 ++++++++++++++++++--------------------
fs/proc/task_mmu.c | 2 +-
include/asm-generic/tlb.h | 4 +-
include/asm-generic/tlbflush.h | 3 +-
kernel/fork.c | 2 +-
mm/memory.c | 9 +++--
9 files changed, 47 insertions(+), 47 deletions(-)

diff --git a/arch/x86/include/asm/tlb.h b/arch/x86/include/asm/tlb.h
index 829215f..505fdfe 100644
--- a/arch/x86/include/asm/tlb.h
+++ b/arch/x86/include/asm/tlb.h
@@ -4,7 +4,7 @@
#define tlb_start_vma(tlb, vma) do { } while (0)
#define tlb_end_vma(tlb, vma) do { } while (0)
#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
-#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm)
+#define tlb_flush(tlb, start, end) flush_tlb_mm((tlb)->mm, start, end)

#include <asm-generic/tlb.h>

diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index 51f8b1c..d1baeac 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -89,7 +89,8 @@ static inline void __flush_tlb_one(unsigned long addr)
#define flush_tlb_all() __flush_tlb_all()
#define local_flush_tlb() __flush_tlb()

-static inline void flush_tlb_mm(struct mm_struct *mm)
+static inline void flush_tlb_mm(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
{
if (mm == current->active_mm)
__flush_tlb();
@@ -128,7 +129,7 @@ static inline void reset_lazy_tlbstate(void)

extern void flush_tlb_all(void);
extern void flush_tlb_current_task(void);
-extern void flush_tlb_mm(struct mm_struct *);
+extern void flush_tlb_mm(struct mm_struct *, unsigned long, unsigned long);
extern void flush_tlb_page(struct vm_area_struct *, unsigned long);
extern void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 8573b83..5aea5b0 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -168,7 +168,7 @@ void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
* section 8.1: in PAE mode we explicitly have to flush the
* TLB via cr3 if the top-level pgd is changed...
*/
- flush_tlb_mm(mm);
+ flush_tlb_mm(mm, 0UL, -1UL);
}
#else /* !CONFIG_X86_PAE */

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 91896dc..ef39781 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -298,22 +298,6 @@ void flush_tlb_current_task(void)
preempt_enable();
}

-void flush_tlb_mm(struct mm_struct *mm)
-{
- preempt_disable();
-
- if (current->active_mm == mm) {
- if (current->mm)
- local_flush_tlb();
- else
- leave_mm(smp_processor_id());
- }
- if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
- flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL, 0UL);
-
- preempt_enable();
-}
-
static inline int has_large_page(struct mm_struct *mm,
unsigned long start, unsigned long end)
{
@@ -336,39 +320,32 @@ static inline int has_large_page(struct mm_struct *mm,
return 0;
}

-void flush_tlb_range(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
+void __flush_tlb_range(struct mm_struct *mm, unsigned long start,
+ unsigned long end, unsigned long vmflag)
{
- struct mm_struct *mm;
-
- if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
- || !tlb_flushall_factor) {
-flush_all:
- flush_tlb_mm(vma->vm_mm);
- return;
- }
-
preempt_disable();
- mm = vma->vm_mm;
if (current->active_mm == mm) {
if (current->mm) {
- unsigned long addr, vmflag = vma->vm_flags;
- unsigned act_entries, tlb_entries = 0;
+ unsigned long addr;
+ unsigned long act_entries, tlb_entries = 0;

+ if (start == TLB_FLUSH_ALL || end == -1UL
+ || !tlb_flushall_factor) {
+ local_flush_tlb();
+ goto flush_all;
+ }
if (vmflag & VM_EXEC)
tlb_entries = tlb_lli_4k[ENTRIES];
else
tlb_entries = tlb_lld_4k[ENTRIES];
-
- act_entries = tlb_entries > mm->total_vm ?
- mm->total_vm : tlb_entries;
+ act_entries = min(mm->total_vm, tlb_entries);

if ((end - start)/PAGE_SIZE >
act_entries/tlb_flushall_factor)
local_flush_tlb();
else {
if (has_large_page(mm, start, end)) {
- preempt_enable();
+ local_flush_tlb();
goto flush_all;
}
for (addr = start; addr <= end;
@@ -386,11 +363,31 @@ flush_all:
leave_mm(smp_processor_id());
}
}
+
+flush_all:
if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL, 0UL);
preempt_enable();
}

+void flush_tlb_mm(struct mm_struct *mm, unsigned long start, unsigned long end)
+{
+ __flush_tlb_range(mm, start, end, 0UL);
+}
+
+void flush_tlb_range(struct vm_area_struct *vma,
+ unsigned long start, unsigned long end)
+{
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long vmflag = vma->vm_flags;
+
+ if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
+ || !tlb_flushall_factor)
+ __flush_tlb_range(mm, 0UL, -1UL, 0);
+ else
+ __flush_tlb_range(mm, start, end, vmflag);
+}
+

void flush_tlb_page(struct vm_area_struct *vma, unsigned long start)
{
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2d60492..5728c8f 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -660,7 +660,7 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
walk_page_range(vma->vm_start, vma->vm_end,
&clear_refs_walk);
}
- flush_tlb_mm(mm);
+ flush_tlb_mm(mm, 0UL, -1UL);
up_read(&mm->mmap_sem);
mmput(mm);
}
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index f96a5b5..24e205d 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -112,7 +112,7 @@ static inline int tlb_fast_mode(struct mmu_gather *tlb)
}

void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm);
-void tlb_flush_mmu(struct mmu_gather *tlb);
+void tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end);
void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end);
int __tlb_remove_page(struct mmu_gather *tlb, struct page *page);

@@ -123,7 +123,7 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page);
static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
{
if (!__tlb_remove_page(tlb, page))
- tlb_flush_mmu(tlb);
+ tlb_flush_mmu(tlb, 0UL, -1UL);
}

/**
diff --git a/include/asm-generic/tlbflush.h b/include/asm-generic/tlbflush.h
index d6d0a88..db1d4bb 100644
--- a/include/asm-generic/tlbflush.h
+++ b/include/asm-generic/tlbflush.h
@@ -11,7 +11,8 @@

#include <linux/bug.h>

-static inline void flush_tlb_mm(struct mm_struct *mm)
+static inline void flush_tlb_mm(struct mm_struct *mm,
+ unsigned long start, unsigned long end)
{
BUG();
}
diff --git a/kernel/fork.c b/kernel/fork.c
index b9372a0..a4f0c64 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -427,7 +427,7 @@ static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
retval = 0;
out:
up_write(&mm->mmap_sem);
- flush_tlb_mm(oldmm);
+ flush_tlb_mm(oldmm, 0UL, -1UL);
up_write(&oldmm->mmap_sem);
return retval;
fail_nomem_anon_vma_fork:
diff --git a/mm/memory.c b/mm/memory.c
index 6105f47..05e2c2e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -218,14 +218,15 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
#endif
}

-void tlb_flush_mmu(struct mmu_gather *tlb)
+void tlb_flush_mmu(struct mmu_gather *tlb,
+ unsigned long start, unsigned long end)
{
struct mmu_gather_batch *batch;

if (!tlb->need_flush)
return;
tlb->need_flush = 0;
- tlb_flush(tlb);
+ tlb_flush(tlb, start, end);
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
tlb_table_flush(tlb);
#endif
@@ -248,7 +249,7 @@ void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long e
{
struct mmu_gather_batch *batch, *next;

- tlb_flush_mmu(tlb);
+ tlb_flush_mmu(tlb, start, end);

/* keep the page table cache within bounds */
check_pgt_cache();
@@ -1204,7 +1205,7 @@ again:
*/
if (force_flush) {
force_flush = 0;
- tlb_flush_mmu(tlb);
+ tlb_flush_mmu(tlb, addr, end);
if (addr != end)
goto again;
}
--
1.7.5.4

2012-05-08 14:06:03

[permalink] [raw]

Subject: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

kernel will replace cr3 rewrite with invlpg when
tlb flush entries <= 1/tlb_flushall_factor
if tlb_flushall_factor is 0, kernel won't do this replace.

User can modify its value according to specific applications.

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/kernel/cpu/intel.c | 35 +++++++++++++++++++++++++++++++++++
drivers/base/cpu.c | 2 ++
include/linux/cpu.h | 2 ++
3 files changed, 39 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 42480c6..8a14081 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -662,6 +662,41 @@ void intel_cpu_detect_tlb(struct cpuinfo_x86 *c)
intel_tlb_flushall_factor_set(c);
}

+static ssize_t __tlb_flushall_factor_store(const char *buf,
+ size_t count, int smt)
+{
+ unsigned int factor = 0;
+
+ if (sscanf(buf, "%u", &factor) != 1)
+ return -EINVAL;
+
+ tlb_flushall_factor = factor;
+
+ return count;
+}
+
+static ssize_t tlb_flushall_factor_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ return sprintf(buf, "%u\n", tlb_flushall_factor);
+}
+static ssize_t tlb_flushall_factor_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ return __tlb_flushall_factor_store(buf, count, 0);
+}
+
+static DEVICE_ATTR(tlb_flushall_factor, 0644,
+ tlb_flushall_factor_show,
+ tlb_flushall_factor_store);
+
+int __init create_sysfs_tlb_flushall_factor(struct device *dev)
+{
+ return device_create_file(dev, &dev_attr_tlb_flushall_factor);
+}
+
static const struct cpu_dev __cpuinitconst intel_cpu_dev = {
.c_vendor = "Intel",
.c_ident = { "GenuineIntel" },
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index adf937b..b46e1b9 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -331,6 +331,8 @@ void __init cpu_dev_init(void)

cpu_dev_register_generic();

+ create_sysfs_tlb_flushall_factor(cpu_subsys.dev_root);
+
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
sched_create_sysfs_power_savings_entries(cpu_subsys.dev_root);
#endif
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index ee28844..5c953b0 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -36,6 +36,8 @@ extern void cpu_remove_dev_attr(struct device_attribute *attr);
extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);

+extern int create_sysfs_tlb_flushall_factor(struct device *dev);
+
extern int sched_create_sysfs_power_savings_entries(struct device *dev);

#ifdef CONFIG_HOTPLUG_CPU
--
1.7.5.4

2012-05-08 14:05:17

[permalink] [raw]

Subject: [PATCH v3 1/7] x86/tlb_info: get last level TLB entry number of CPU

For 4KB pages, x86 CPU has 2 or 1 level TLB, first level is data TLB and
instruction TLB, second level is shared TLB for both data and instructions.

For hupe page TLB, usually there is just one level and seperated by 2MB/4MB
and 1GB.

Although each levels TLB size is important for performance tuning, but for
genernal and rude optimizing, last level TLB entry number is suitable. And
in fact, last level TLB always has the biggest entry number.

This patch will get the biggest TLB entry number and use it in furture TLB
optimizing.

For all kinds of x86 vendor friendly, vendor specific code was moved to its
specific files.

Signed-off-by: Alex Shi <[email protected]>
---
arch/x86/include/asm/processor.h | 11 +++
arch/x86/kernel/cpu/common.c | 21 ++++++
arch/x86/kernel/cpu/cpu.h | 9 +++
arch/x86/kernel/cpu/intel.c | 141 ++++++++++++++++++++++++++++++++++++++
4 files changed, 182 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4fa7dcc..797faca 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -61,6 +61,17 @@ static inline void *current_text_addr(void)
# define ARCH_MIN_MMSTRUCT_ALIGN 0
#endif

+enum tlb_infos {
+ ENTRIES,
+ NR_INFO
+};
+
+extern u16 __read_mostly tlb_lli_4k[NR_INFO];
+extern u16 __read_mostly tlb_lli_2m[NR_INFO];
+extern u16 __read_mostly tlb_lli_4m[NR_INFO];
+extern u16 __read_mostly tlb_lld_4k[NR_INFO];
+extern u16 __read_mostly tlb_lld_2m[NR_INFO];
+extern u16 __read_mostly tlb_lld_4m[NR_INFO];
/*
* CPU type and hardware bug flags. Kept separately for each CPU.
* Members of this structure are referenced in head.S, so think twice
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index cf79302..0152082 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -452,6 +452,25 @@ void __cpuinit cpu_detect_cache_sizes(struct cpuinfo_x86 *c)
c->x86_cache_size = l2size;
}

+u16 __read_mostly tlb_lli_4k[NR_INFO];
+u16 __read_mostly tlb_lli_2m[NR_INFO];
+u16 __read_mostly tlb_lli_4m[NR_INFO];
+u16 __read_mostly tlb_lld_4k[NR_INFO];
+u16 __read_mostly tlb_lld_2m[NR_INFO];
+u16 __read_mostly tlb_lld_4m[NR_INFO];
+
+void __cpuinit cpu_detect_tlb(struct cpuinfo_x86 *c)
+{
+ if (c->x86_vendor == X86_VENDOR_INTEL)
+ intel_cpu_detect_tlb(c);
+
+ printk(KERN_INFO "Last level iTLB entries: 4KB %d, 2MB %d, 4MB %d\n" \
+ "Last level dTLB entries: 4KB %d, 2MB %d, 4MB %d\n",
+ tlb_lli_4k[ENTRIES], tlb_lli_2m[ENTRIES],
+ tlb_lli_4m[ENTRIES], tlb_lld_4k[ENTRIES],
+ tlb_lld_2m[ENTRIES], tlb_lld_4m[ENTRIES]);
+}
+
void __cpuinit detect_ht(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_X86_HT
@@ -911,6 +930,8 @@ void __init identify_boot_cpu(void)
#else
vgetcpu_set_mode();
#endif
+ if (boot_cpu_data.cpuid_level >= 2)
+ cpu_detect_tlb(&boot_cpu_data);
}

void __cpuinit identify_secondary_cpu(struct cpuinfo_x86 *c)
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index 8bacc78..c8dc726 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -24,6 +24,14 @@ struct cpu_dev {
int c_x86_vendor;
};

+struct _tlb_table {
+ unsigned char descriptor;
+ char tlb_type;
+ unsigned int entries;
+ /* unsigned int ways; */
+ char info[128];
+};
+
#define cpu_dev_register(cpu_devX) \
static const struct cpu_dev *const __cpu_dev_##cpu_devX __used \
__attribute__((__section__(".x86_cpu_dev.init"))) = \
@@ -34,4 +42,5 @@ extern const struct cpu_dev *const __x86_cpu_dev_start[],

extern void get_cpu_cap(struct cpuinfo_x86 *c);
extern void cpu_detect_cache_sizes(struct cpuinfo_x86 *c);
+extern void intel_cpu_detect_tlb(struct cpuinfo_x86 *c);
#endif /* ARCH_X86_CPU_H */
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 3e6ff6c..86e6131 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -491,6 +491,147 @@ static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 *c, unsigned i
}
#endif

+#define TLB_INST_4K 0x01
+#define TLB_INST_4M 0x02
+#define TLB_INST_2M_4M 0x03
+
+#define TLB_INST_ALL 0x05
+#define TLB_INST_1G 0x06
+
+#define TLB_DATA_4K 0x11
+#define TLB_DATA_4M 0x12
+#define TLB_DATA_2M_4M 0x13
+#define TLB_DATA_4K_4M 0x14
+
+#define TLB_DATA_1G 0x16
+
+#define TLB_DATA0_4K 0x21
+#define TLB_DATA0_4M 0x22
+#define TLB_DATA0_2M_4M 0x23
+
+#define STLB_4K 0x41
+
+static const struct _tlb_table intel_tlb_table[] = {
+ { 0x01, TLB_INST_4K, 32, " TLB_INST 4 KByte pages, 4-way set associative" },
+ { 0x02, TLB_INST_4M, 2, " TLB_INST 4 MByte pages, full associative" },
+ { 0x03, TLB_DATA_4K, 64, " TLB_DATA 4 KByte pages, 4-way set associative" },
+ { 0x04, TLB_DATA_4M, 8, " TLB_DATA 4 MByte pages, 4-way set associative" },
+ { 0x05, TLB_DATA_4M, 32, " TLB_DATA 4 MByte pages, 4-way set associative" },
+ { 0x0b, TLB_INST_4M, 4, " TLB_INST 4 MByte pages, 4-way set associative" },
+ { 0x4f, TLB_INST_4K, 32, " TLB_INST 4 KByte pages */" },
+ { 0x50, TLB_INST_ALL, 64, " TLB_INST 4 KByte and 2-MByte or 4-MByte pages" },
+ { 0x51, TLB_INST_ALL, 128, " TLB_INST 4 KByte and 2-MByte or 4-MByte pages" },
+ { 0x52, TLB_INST_ALL, 256, " TLB_INST 4 KByte and 2-MByte or 4-MByte pages" },
+ { 0x55, TLB_INST_2M_4M, 7, " TLB_INST 2-MByte or 4-MByte pages, fully associative" },
+ { 0x56, TLB_DATA0_4M, 16, " TLB_DATA0 4 MByte pages, 4-way set associative" },
+ { 0x57, TLB_DATA0_4K, 16, " TLB_DATA0 4 KByte pages, 4-way associative" },
+ { 0x59, TLB_DATA0_4K, 16, " TLB_DATA0 4 KByte pages, fully associative" },
+ { 0x5a, TLB_DATA0_2M_4M, 32, " TLB_DATA0 2-MByte or 4 MByte pages, 4-way set associative" },
+ { 0x5b, TLB_DATA_4K_4M, 64, " TLB_DATA 4 KByte and 4 MByte pages" },
+ { 0x5c, TLB_DATA_4K_4M, 128, " TLB_DATA 4 KByte and 4 MByte pages" },
+ { 0x5d, TLB_DATA_4K_4M, 256, " TLB_DATA 4 KByte and 4 MByte pages" },
+ { 0xb0, TLB_INST_4K, 128, " TLB_INST 4 KByte pages, 4-way set associative" },
+ { 0xb1, TLB_INST_2M_4M, 4, " TLB_INST 2M pages, 4-way, 8 entries or 4M pages, 4-way entries" },
+ { 0xb2, TLB_INST_4K, 64, " TLB_INST 4KByte pages, 4-way set associative" },
+ { 0xb3, TLB_DATA_4K, 128, " TLB_DATA 4 KByte pages, 4-way set associative" },
+ { 0xb4, TLB_DATA_4K, 256, " TLB_DATA 4 KByte pages, 4-way associative" },
+ { 0xba, TLB_DATA_4K, 64, " TLB_DATA 4 KByte pages, 4-way associative" },
+ { 0xc0, TLB_DATA_4K_4M, 8, " TLB_DATA 4 KByte and 4 MByte pages, 4-way associative" },
+ { 0xca, STLB_4K, 512, " STLB 4 KByte pages, 4-way associative" },
+ { 0x00, 0, 0 }
+};
+
+void intel_tlb_lookup(const unsigned char desc)
+{
+ unsigned char k;
+ if (desc == 0)
+ return;
+
+ /* look up this descriptor in the table */
+ for (k = 0; intel_tlb_table[k].descriptor != desc && \
+ intel_tlb_table[k].descriptor != 0; k++)
+ ;
+
+ if (intel_tlb_table[k].tlb_type == 0)
+ return;
+
+ switch (intel_tlb_table[k].tlb_type) {
+ case STLB_4K:
+ if (tlb_lli_4k[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_4k[ENTRIES] = intel_tlb_table[k].entries;
+ if (tlb_lld_4k[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_4k[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_INST_ALL:
+ if (tlb_lli_4k[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_4k[ENTRIES] = intel_tlb_table[k].entries;
+ if (tlb_lli_2m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_2m[ENTRIES] = intel_tlb_table[k].entries;
+ if (tlb_lli_4m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_4m[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_INST_4K:
+ if (tlb_lli_4k[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_4k[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_INST_4M:
+ if (tlb_lli_4m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_4m[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_INST_2M_4M:
+ if (tlb_lli_2m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_2m[ENTRIES] = intel_tlb_table[k].entries;
+ if (tlb_lli_4m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lli_4m[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_DATA_4K:
+ case TLB_DATA0_4K:
+ if (tlb_lld_4k[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_4k[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_DATA_4M:
+ case TLB_DATA0_4M:
+ if (tlb_lld_4m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_4m[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_DATA_2M_4M:
+ case TLB_DATA0_2M_4M:
+ if (tlb_lld_2m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_2m[ENTRIES] = intel_tlb_table[k].entries;
+ if (tlb_lld_4m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_4m[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ case TLB_DATA_4K_4M:
+ if (tlb_lld_4k[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_4k[ENTRIES] = intel_tlb_table[k].entries;
+ if (tlb_lld_4m[ENTRIES] < intel_tlb_table[k].entries)
+ tlb_lld_4m[ENTRIES] = intel_tlb_table[k].entries;
+ break;
+ }
+}
+
+void intel_cpu_detect_tlb(struct cpuinfo_x86 *c)
+{
+ int i, j, n;
+ unsigned int regs[4];
+ unsigned char *desc = (unsigned char *)regs;
+ /* Number of times to iterate */
+ n = cpuid_eax(2) & 0xFF;
+
+ for (i = 0 ; i < n ; i++) {
+ cpuid(2, &regs[0], &regs[1], &regs[2], &regs[3]);
+
+ /* If bit 31 is set, this is an unknown format */
+ for (j = 0 ; j < 3 ; j++)
+ if (regs[j] & (1 << 31))
+ regs[j] = 0;
+
+ /* Byte 0 is level count, not a descriptor */
+ for (j = 1 ; j < 16 ; j++)
+ intel_tlb_lookup(desc[j]);
+ }
+}
+
static const struct cpu_dev __cpuinitconst intel_cpu_dev = {
.c_vendor = "Intel",
.c_ident = { "GenuineIntel" },
--
1.7.5.4

2012-05-08 15:02:46

[permalink] [raw]

Subject: Re: [PATCH v3] TLB flush optimization

On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
> This version just added 2 patches, the 6th and 7th. The first 5 patches are
> same as v2.
>
> Seems it is a little hard for me to find a real case to show performance gain.
> But the advantage is there ture.
>
> Any comments are appreciated!
>
> Alex
>
> [PATCH v3 1/7] x86/tlb_info: get last level TLB entry number of CPU
> [PATCH v3 2/7] x86/flush_tlb: try flush_tlb_single one by one in
> [PATCH v3 3/7] x86/tlb: fall back to flush all when meet a THP large
> [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs
> [PATCH v3 5/7] x86/tlb: remove comments for tlb_flush_range
> [PATCH v3 6/7] x86/tlb: optimizing flush_tlb_mm
> [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user

Have you tried what happens if you get rid of the funny multi-vector-ipi
scheme and use the generic smp_call functions?

2012-05-08 15:08:35

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
> +void intel_tlb_flushall_factor_set(struct cpuinfo_x86 *c)
> +{
> + switch (c->x86_model) {
> + case 15: /* original 65 nm celeron/pentium/core2/xeon, "Merom"/"Conroe" */
> + tlb_flushall_factor = 0;
> + break;

Why isn't this is the bottom list of core chips?

> + case 26: /* 45 nm nehalem, "Bloomfield" */
> + case 30: /* 45 nm nehalem, "Lynnfield" */
> + case 37: /* 32 nm nehalem, "Clarkdale" */
> + case 44: /* 32 nm nehalem, "Gulftown" */
> + case 46: /* 45 nm nehalem-ex, "Beckton" */
> + tlb_flushall_factor = 64;
> + break;
> + case 42: /* SandyBridge */
> + case 45: /* SandyBridge, "Romely-EP" */
> + tlb_flushall_factor = 32;
> + break;
> + case 28: /* Atom */
> + case 47: /* 32 nm Xeon E7 */

This is a wsm-ex, right? Why isn't it listed with the other nehalems?

> + case 14: /* 65 nm core solo/duo, "Yonah" */
> + case 22: /* single-core 65 nm celeron/core2solo "Merom-L"/"Conroe-L" */
> + case 23: /* current 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
> + case 29: /* six-core 45 nm xeon "Dunnington" */

So never use invlpg for Atom/Core/Core2?

> + default:
> + tlb_flushall_factor = 0;
> + }
> +}

> @@ -364,7 +363,8 @@ flush_all:
> act_entries = tlb_entries > mm->total_vm ?
> mm->total_vm : tlb_entries;
>
> + if ((end - start)/PAGE_SIZE >
> + act_entries/tlb_flushall_factor)

You're doing an actual full division, wouldn't a shift be better?

2012-05-08 15:10:12

[permalink] [raw]

Subject: Re: [PATCH v3 6/7] x86/tlb: optimizing flush_tlb_mm

On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
> This patch is changing flush_tlb_mm(mm) to flush_tlb_mm(mm, start,
> end)
> in cases.

Uhm, no please don't. That's called flush_tlb_range().

2012-05-08 15:12:12

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
> kernel will replace cr3 rewrite with invlpg when
> tlb flush entries <= 1/tlb_flushall_factor
> if tlb_flushall_factor is 0, kernel won't do this replace.
>
> User can modify its value according to specific applications.

Yay!, another useless config knob :-(

2012-05-08 15:13:55

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On 05/08/2012 07:03 AM, Alex Shi wrote:
> --- a/arch/x86/kernel/cpu/intel.c
> +++ b/arch/x86/kernel/cpu/intel.c
> @@ -610,6 +610,35 @@ void intel_tlb_lookup(const unsigned char desc)
> }
> }
>
> +void intel_tlb_flushall_factor_set(struct cpuinfo_x86 *c)
> +{
> + switch (c->x86_model) {
> + case 15: /* original 65 nm celeron/pentium/core2/xeon, "Merom"/"Conroe" */
> + tlb_flushall_factor = 0;
> + break;
> + case 26: /* 45 nm nehalem, "Bloomfield" */
> + case 30: /* 45 nm nehalem, "Lynnfield" */
> + case 37: /* 32 nm nehalem, "Clarkdale" */
> + case 44: /* 32 nm nehalem, "Gulftown" */
> + case 46: /* 45 nm nehalem-ex, "Beckton" */
> + tlb_flushall_factor = 64;
> + break;
> + case 42: /* SandyBridge */
> + case 45: /* SandyBridge, "Romely-EP" */
> + tlb_flushall_factor = 32;
> + break;
> + case 28: /* Atom */
> + case 47: /* 32 nm Xeon E7 */
> + case 14: /* 65 nm core solo/duo, "Yonah" */
> + case 22: /* single-core 65 nm celeron/core2solo "Merom-L"/"Conroe-L" */
> + case 23: /* current 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
> + case 29: /* six-core 45 nm xeon "Dunnington" */
> +
> + default:
> + tlb_flushall_factor = 0;
> + }
> +}
> +

This uses x86_model without qualifying it x86 (family), however that is
meaningless. All the CPUs you are dealing with above have c->x86 == 6,
but you need to handle others correctly (even if that just means
defaulting it to zero.)

One way to do that is to do:

switch ((c->x86 << 8) + c->x86_model) {

... and use numbers like 0x62d instead of 45.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

2012-05-08 15:16:40

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On 05/08/2012 07:03 AM, Alex Shi wrote:
>
> like some machine in my hands, balance points is 16 entries on Romely-EP;
> while it is at 8 entries on Bloomfield NHM-EP; but on model 15 core2 Xeon
> using invlpg has nothing help.
>
> For untested machine, no optimization now.
>

This seems a bit concerning from a forward compatibility point of view.
It would make more sense to assume that future processors would behave
more like the most recent (Sandy Bridge in your case) unless there is
evidence to the contrary.

>
> - if ((end - start)/PAGE_SIZE > act_entries/FLUSHALL_BAR)
> + if ((end - start)/PAGE_SIZE >
> + act_entries/tlb_flushall_factor)
> local_flush_tlb();

You are doing a dynamic division (and on unknown/older CPUs you're
dividing by zero!!) but all your divisors are powers of two. Make it a
shift instead.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

2012-05-08 15:19:07

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On 05/08/2012 07:03 AM, Alex Shi wrote:
>
> - if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB) {
> + if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
> + || !tlb_flushall_factor) {

OK nevermind on the division by zero, but this yet another test being
performed.

If nothing else you could fold these tests and make tlb_flushall_factor
zero if !cpu_has_invlpg.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

2012-05-08 15:22:07

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On 05/08/2012 08:11 AM, Peter Zijlstra wrote:
> On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
>> kernel will replace cr3 rewrite with invlpg when
>> tlb flush entries <= 1/tlb_flushall_factor
>> if tlb_flushall_factor is 0, kernel won't do this replace.
>>
>> User can modify its value according to specific applications.
>
> Yay!, another useless config knob :-(
>

I think this one is mostly for benchmarking new silicon to find out the
proper value, I'm guessing?

-hpa

2012-05-08 15:25:33

by Borislav Petkov

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On Tue, May 08, 2012 at 08:20:25AM -0700, H. Peter Anvin wrote:
> On 05/08/2012 08:11 AM, Peter Zijlstra wrote:
> > On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
> >> kernel will replace cr3 rewrite with invlpg when
> >> tlb flush entries <= 1/tlb_flushall_factor
> >> if tlb_flushall_factor is 0, kernel won't do this replace.
> >>
> >> User can modify its value according to specific applications.
> >
> > Yay!, another useless config knob :-(
> >
>
> I think this one is mostly for benchmarking new silicon to find out the
> proper value, I'm guessing?

Yep, this was supposed to be for pinpointing the proper entries count.
I believe we don't have this thing of having code intree but not really
intree - only for testing new silicon. Maybe a debug module or add this
to debugfs?

--
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551

2012-05-08 15:32:37

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On 05/08/2012 08:25 AM, Borislav Petkov wrote:
>
> Yep, this was supposed to be for pinpointing the proper entries count.
> I believe we don't have this thing of having code intree but not really
> intree - only for testing new silicon. Maybe a debug module or add this
> to debugfs?
>

We have a lot of that kind of code, it is usually hidden under
CONFIG_*DEBUG* something.

-hpa

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

2012-05-08 15:42:05

by Borislav Petkov

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On Tue, May 08, 2012 at 08:31:53AM -0700, H. Peter Anvin wrote:
> On 05/08/2012 08:25 AM, Borislav Petkov wrote:
> >
> > Yep, this was supposed to be for pinpointing the proper entries count.
> > I believe we don't have this thing of having code intree but not really
> > intree - only for testing new silicon. Maybe a debug module or add this
> > to debugfs?
> >
>
> We have a lot of that kind of code, it is usually hidden under
> CONFIG_*DEBUG* something.

Then maybe this is where this knob should go, along with adding it to
debugfs instead of sysfs...

--
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551

2012-05-08 15:50:24

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On 05/08/2012 08:41 AM, Borislav Petkov wrote:
> On Tue, May 08, 2012 at 08:31:53AM -0700, H. Peter Anvin wrote:
>> On 05/08/2012 08:25 AM, Borislav Petkov wrote:
>>>
>>> Yep, this was supposed to be for pinpointing the proper entries count.
>>> I believe we don't have this thing of having code intree but not really
>>> intree - only for testing new silicon. Maybe a debug module or add this
>>> to debugfs?
>>>
>>
>> We have a lot of that kind of code, it is usually hidden under
>> CONFIG_*DEBUG* something.
>
> Then maybe this is where this knob should go, along with adding it to
> debugfs instead of sysfs...
>

I don't see a problem with it in sysfs.

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.

2012-05-08 15:56:43

by Andi Kleen

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

> This seems a bit concerning from a forward compatibility point of view.
> It would make more sense to assume that future processors would behave
> more like the most recent (Sandy Bridge in your case) unless there is
> evidence to the contrary.
This would not work on new Atoms, which inter mix model numbers.

In the past I did a hack in other software to check the cache sizes to
distinguish the two
for unknown models It's not pretty however.

-Andi

2012-05-08 16:10:29

by Greg Kroah-Hartman

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On Tue, May 08, 2012 at 08:48:33AM -0700, H. Peter Anvin wrote:
> On 05/08/2012 08:41 AM, Borislav Petkov wrote:
> > On Tue, May 08, 2012 at 08:31:53AM -0700, H. Peter Anvin wrote:
> >> On 05/08/2012 08:25 AM, Borislav Petkov wrote:
> >>>
> >>> Yep, this was supposed to be for pinpointing the proper entries count.
> >>> I believe we don't have this thing of having code intree but not really
> >>> intree - only for testing new silicon. Maybe a debug module or add this
> >>> to debugfs?
> >>>
> >>
> >> We have a lot of that kind of code, it is usually hidden under
> >> CONFIG_*DEBUG* something.
> >
> > Then maybe this is where this knob should go, along with adding it to
> > debugfs instead of sysfs...
> >
>
> I don't see a problem with it in sysfs.

If it's in sysfs, it better be documented in Documentation/ABI.

2012-05-08 16:28:23

by Borislav Petkov

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On Tue, May 08, 2012 at 09:10:22AM -0700, Greg KH wrote:
> > > Then maybe this is where this knob should go, along with adding it to
> > > debugfs instead of sysfs...
> >
> > I don't see a problem with it in sysfs.
>
> If it's in sysfs, it better be documented in Documentation/ABI.

See what I'm sayin'? And besides, debugfs fits better the purpose of
this, maybe somewhere under <debugfs>/x86/...

--
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551

2012-05-08 16:41:13

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On 05/08/2012 08:56 AM, Andi Kleen wrote:
>
>> This seems a bit concerning from a forward compatibility point of view.
>> It would make more sense to assume that future processors would behave
>> more like the most recent (Sandy Bridge in your case) unless there is
>> evidence to the contrary.
> This would not work on new Atoms, which inter mix model numbers.
>

That is another problem, but there isn't much we (as the Linux
community) can do about that, so we can just do the optimistic thing...

> In the past I did a hack in other software to check the cache sizes to
> distinguish the two
> for unknown models It's not pretty however.

Ick.

-hpa

2012-05-09 01:42:38

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On 05/08/2012 11:18 PM, H. Peter Anvin wrote:

> On 05/08/2012 07:03 AM, Alex Shi wrote:
>>
>> - if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB) {
>> + if (!cpu_has_invlpg || vma->vm_flags & VM_HUGETLB
>> + || !tlb_flushall_factor) {
>
> OK nevermind on the division by zero, but this yet another test being
> performed.
>
> If nothing else you could fold these tests and make tlb_flushall_factor
> zero if !cpu_has_invlpg.

Yes, should be.

>
> -hpa
>

2012-05-09 01:59:32

[permalink] [raw]

Subject: Re: [PATCH v3] TLB flush optimization

>> [PATCH v3 1/7] x86/tlb_info: get last level TLB entry number of CPU
>> [PATCH v3 2/7] x86/flush_tlb: try flush_tlb_single one by one in
>> [PATCH v3 3/7] x86/tlb: fall back to flush all when meet a THP large
>> [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs
>> [PATCH v3 5/7] x86/tlb: remove comments for tlb_flush_range
>> [PATCH v3 6/7] x86/tlb: optimizing flush_tlb_mm
>> [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user
>
> Have you tried what happens if you get rid of the funny multi-vector-ipi
> scheme and use the generic smp_call functions?

Not yet.

2012-05-09 02:05:11

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

On 05/08/2012 11:08 PM, Peter Zijlstra wrote:

> On Tue, 2012-05-08 at 22:03 +0800, Alex Shi wrote:
>> +void intel_tlb_flushall_factor_set(struct cpuinfo_x86 *c)
>> +{
>> + switch (c->x86_model) {
>> + case 15: /* original 65 nm celeron/pentium/core2/xeon, "Merom"/"Conroe" */
>> + tlb_flushall_factor = 0;
>> + break;
>
> Why isn't this is the bottom list of core chips?

It was tested. but the bottom list cpu was not tested.

>
>> + case 26: /* 45 nm nehalem, "Bloomfield" */
>> + case 30: /* 45 nm nehalem, "Lynnfield" */
>> + case 37: /* 32 nm nehalem, "Clarkdale" */
>> + case 44: /* 32 nm nehalem, "Gulftown" */
>> + case 46: /* 45 nm nehalem-ex, "Beckton" */
>> + tlb_flushall_factor = 64;
>> + break;
>> + case 42: /* SandyBridge */
>> + case 45: /* SandyBridge, "Romely-EP" */
>> + tlb_flushall_factor = 32;
>> + break;
>> + case 28: /* Atom */
>> + case 47: /* 32 nm Xeon E7 */
>
> This is a wsm-ex, right? Why isn't it listed with the other nehalems?

I don't know this. Thanks for this info

>
>> + case 14: /* 65 nm core solo/duo, "Yonah" */
>> + case 22: /* single-core 65 nm celeron/core2solo "Merom-L"/"Conroe-L" */
>> + case 23: /* current 45 nm celeron/core2/xeon "Penryn"/"Wolfdale" */
>> + case 29: /* six-core 45 nm xeon "Dunnington" */
>
> So never use invlpg for Atom/Core/Core2?

Uh, I will remove the CPU list if they weren't tested.

>
>> + default:
>> + tlb_flushall_factor = 0;
>> + }
>> +}
>
>
>> @@ -364,7 +363,8 @@ flush_all:
>> act_entries = tlb_entries > mm->total_vm ?
>> mm->total_vm : tlb_entries;
>>
>> + if ((end - start)/PAGE_SIZE >
>> + act_entries/tlb_flushall_factor)
>
> You're doing an actual full division, wouldn't a shift be better?

Thanks!

2012-05-09 02:12:04

[permalink] [raw]

Subject: Re: [PATCH v3 4/7] x86/tlb: add tlb flush all factor for specific CPUs

>

> This uses x86_model without qualifying it x86 (family), however that is
> meaningless. All the CPUs you are dealing with above have c->x86 == 6,
> but you need to handle others correctly (even if that just means
> defaulting it to zero.)
>
> One way to do that is to do:
>
> switch ((c->x86 << 8) + c->x86_model) {
>
> ... and use numbers like 0x62d instead of 45.

Yes, this is better, thanks!

>
> -hpa
>
>

2012-05-09 05:05:23

[permalink] [raw]

Subject: Re: [PATCH v3 7/7] x86/tlb: add tlb_flushall_factor into sysfs for user change

On 05/08/2012 11:48 PM, H. Peter Anvin wrote:

> On 05/08/2012 08:41 AM, Borislav Petkov wrote:
>> On Tue, May 08, 2012 at 08:31:53AM -0700, H. Peter Anvin wrote:
>>> On 05/08/2012 08:25 AM, Borislav Petkov wrote:
>>>>
>>>> Yep, this was supposed to be for pinpointing the proper entries count.
>>>> I believe we don't have this thing of having code intree but not really
>>>> intree - only for testing new silicon. Maybe a debug module or add this
>>>> to debugfs?
>>>>
>>>
>>> We have a lot of that kind of code, it is usually hidden under
>>> CONFIG_*DEBUG* something.
>>
>> Then maybe this is where this knob should go, along with adding it to
>> debugfs instead of sysfs...
>>
>
> I don't see a problem with it in sysfs.
>

Ok. I will modify it according to comments.

2012-05-09 08:22:42

by Nicholas Piggin

[permalink] [raw]

Subject: Re: [PATCH v3 5/7] x86/tlb: remove comments for tlb_flush_range implement suggestion

On 9 May 2012 00:03, Alex Shi <[email protected]> wrote:
> Thanks to this comments that inspired me using invlpg to replace cr3
> rewrite.
> Now, it is time to remove from code to avoid reader confusing.

Nitpick, but this should just be folded into the patch which does the
invlpg conversion.

>
> Signed-off-by: Alex Shi <[email protected]>
> ---
> arch/x86/include/asm/tlbflush.h | 4 ----
> 1 files changed, 0 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
> index ec30dfb..51f8b1c 100644
> --- a/arch/x86/include/asm/tlbflush.h
> +++ b/arch/x86/include/asm/tlbflush.h
> @@ -81,10 +81,6 @@ static inline void __flush_tlb_one(unsigned long addr)
> *
> * ..but the i386 has somewhat limited tlb flushing capabilities,
> * and page-granular flushes are available only on i486 and up.
> - *
> - * x86-64 can only flush individual pages or full VMs. For a range flush
> - * we always do the full VM. Might be worth trying if for a small
> - * range a few INVLPGs in a row are a win.
> */
>
> #ifndef CONFIG_SMP
> --
> 1.7.5.4
>
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2012-05-09 23:45:15

by Andi Kleen

[permalink] [raw]

Subject: Re: [PATCH v3] TLB flush optimization

> Have you tried what happens if you get rid of the funny multi-vector-ipi
> scheme and use the generic smp_call functions?

Yes we did. It's much faster on larger systems.

But haven't sent the patch yet because wasn't sure if it wasn't slower
on small systems.

-Andi

--
[email protected] -- Speaking for myself only

2012-05-10 05:07:34