2019-04-10 22:48:33

by Atish Patra

[permalink] [raw]
Subject: [0/3] TLB flush counters

The RISC-V patch (2/3) is based on Gary's TLB flush patch series

https://patchwork.kernel.org/project/linux-riscv/list/?series=97315

The x86 kconfig fix patch(1/3) can be applied separately.

Atish Patra (3):
x86: Update DEBUG_TLBFLUSH options description.
RISC-V: Update tlb flush counters
RISC-V: Add DEBUG_TLBFLUSH option.

arch/riscv/Kconfig.debug | 12 ++++++++++++
arch/riscv/include/asm/tlbflush.h | 5 +++++
arch/riscv/mm/tlbflush.c | 12 ++++++++++++
arch/x86/Kconfig.debug | 15 +++------------
4 files changed, 32 insertions(+), 12 deletions(-)

--
2.21.0


2019-04-10 22:46:03

by Atish Patra

[permalink] [raw]
Subject: [2/3] RISC-V: Update tlb flush counters

The TLB flush counters under vmstat seems to be very helpful while
debugging TLB flush performance in RISC-V.

Update the counters in every TLB flush methods respectively.

Signed-off-by: Atish Patra <[email protected]>
---
arch/riscv/include/asm/tlbflush.h | 5 +++++
arch/riscv/mm/tlbflush.c | 12 ++++++++++++
2 files changed, 17 insertions(+)

diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index 29a780ca232a..19779a083f52 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -9,6 +9,7 @@
#define _ASM_RISCV_TLBFLUSH_H

#include <linux/mm_types.h>
+#include <linux/vmstat.h>

/*
* Flush entire local TLB. 'sfence.vma' implicitly fences with the instruction
@@ -16,11 +17,13 @@
*/
static inline void local_flush_tlb_all(void)
{
+ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
__asm__ __volatile__ ("sfence.vma" : : : "memory");
}

static inline void local_flush_tlb_mm(struct mm_struct *mm)
{
+ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
/* Flush ASID 0 so that global mappings are not affected */
__asm__ __volatile__ ("sfence.vma x0, %0" : : "r" (0) : "memory");
}
@@ -28,6 +31,7 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
static inline void local_flush_tlb_page(struct vm_area_struct *vma,
unsigned long addr)
{
+ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
__asm__ __volatile__ ("sfence.vma %0, %1"
: : "r" (addr), "r" (0)
: "memory");
@@ -35,6 +39,7 @@ static inline void local_flush_tlb_page(struct vm_area_struct *vma,

static inline void local_flush_tlb_kernel_page(unsigned long addr)
{
+ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory");
}

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index ceee76f14a0a..8072d7da32bb 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -4,6 +4,8 @@
*/

#include <linux/mm.h>
+#include <linux/vmstat.h>
+#include <linux/cpumask.h>
#include <asm/sbi.h>

#define SFENCE_VMA_FLUSH_ALL ((unsigned long) -1)
@@ -110,6 +112,7 @@ static void ipi_remote_sfence_vma(void *info)
unsigned long size = data->size;
unsigned long i;

+ count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
if (size == SFENCE_VMA_FLUSH_ALL) {
local_flush_tlb_all();
}
@@ -129,6 +132,8 @@ static void ipi_remote_sfence_vma_asid(void *info)
unsigned long size = data->size;
unsigned long i;

+ count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
+ /* Flush entire MM context */
if (size == SFENCE_VMA_FLUSH_ALL) {
__asm__ __volatile__ ("sfence.vma x0, %0"
: : "r" (asid)
@@ -158,6 +163,13 @@ static void remote_sfence_vma(unsigned long start, unsigned long size)
static void remote_sfence_vma_asid(cpumask_t *mask, unsigned long start,
unsigned long size, unsigned long asid)
{
+ int cpuid = smp_processor_id();
+
+ if (cpumask_equal(mask, cpumask_of(cpuid)))
+ count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
+ else
+ count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
+
if (tlbi_ipi) {
struct tlbi info = {
.start = start,
--
2.21.0

2019-04-10 22:46:12

by Atish Patra

[permalink] [raw]
Subject: [1/3] x86: Update DEBUG_TLBFLUSH options description.

CONFIG_DEBUG_TLBFLUSH was added in 'commit 3df3212f9722 ("x86/tlb: add
tlb_flushall_shift knob into debugfs")' to support tlb_flushall_shift
knob. The knob was removed in 'commit e9f4e0a9fe27 ("x86/mm: Rip out
complicated, out-of-date, buggy TLB flushing")'. However, the debug
option was never removed from Kconfig. It was reused in commit
'9824cf9753ec ("mm: vmstats: tlb flush counters")' but the commit text was
never updated accordingly.

Update the Kconfig option description as per its current usage.

Signed-off-by: Atish Patra <[email protected]>
---
arch/x86/Kconfig.debug | 15 +++------------
1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 15d0fbe27872..c1a48d4ffebb 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -125,21 +125,12 @@ config DOUBLEFAULT
hair.

config DEBUG_TLBFLUSH
- bool "Set upper limit of TLB entries to flush one-by-one"
+ bool "Save tlb flush statstics to vmstat"
depends on DEBUG_KERNEL
---help---

- X86-only for now.
-
- This option allows the user to tune the amount of TLB entries the
- kernel flushes one-by-one instead of doing a full TLB flush. In
- certain situations, the former is cheaper. This is controlled by the
- tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
- to -1, the code flushes the whole TLB unconditionally. Otherwise,
- for positive values of it, the kernel will use single TLB entry
- invalidating instructions according to the following formula:
-
- flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
+ Add tlbflush statstics to vmstat. It is really helpful understand tlbflush
+ performance and behavior. It should be enabled only for debugging purpose.

If in doubt, say "N".

--
2.21.0

2019-04-10 22:46:26

by Atish Patra

[permalink] [raw]
Subject: [3/3] RISC-V: Add DEBUG_TLBFLUSH option.

The TLB flush counters under vmstat seems to be very helpful while
debugging TLB flush performance in RISC-V.

Add the Kconfig option only for debug kernels.

Signed-off-by: Atish Patra <[email protected]>
---
arch/riscv/Kconfig.debug | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/arch/riscv/Kconfig.debug b/arch/riscv/Kconfig.debug
index e69de29bb2d1..6a2d3762aeda 100644
--- a/arch/riscv/Kconfig.debug
+++ b/arch/riscv/Kconfig.debug
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config DEBUG_TLBFLUSH
+ bool "Save tlb flush statstics to vmstat"
+ depends on DEBUG_KERNEL
+ help
+
+ Add TLB flush statstics to vmstat. It is really helpful understand tlbflush
+ performance and behavior. It should be enabled only for debugging purpose.
+
+ If in doubt, say "N".
+
--
2.21.0

2019-04-11 06:57:44

by Christoph Hellwig

[permalink] [raw]
Subject: Re: [1/3] x86: Update DEBUG_TLBFLUSH options description.

Given that this option enables generic code (which you reuse for RISC-V
later in this series) please also move the config option to
mm/Kconfig, proabbly keyed off another ARCH_HAVE_DEBUG_TLBFLUSH
symbol that the architecture can select.

2019-04-12 20:17:37

by Atish Patra

[permalink] [raw]
Subject: Re: [1/3] x86: Update DEBUG_TLBFLUSH options description.

On 4/10/19 11:56 PM, Christoph Hellwig wrote:
> Given that this option enables generic code (which you reuse for RISC-V
> later in this series) please also move the config option to
> mm/Kconfig, proabbly keyed off another ARCH_HAVE_DEBUG_TLBFLUSH
> symbol that the architecture can select.
>

Sure.

Regards,
Atish
> _______________________________________________
> linux-riscv mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-riscv
>

2019-04-14 14:31:04

by Borislav Petkov

[permalink] [raw]
Subject: Re: [1/3] x86: Update DEBUG_TLBFLUSH options description.

On Fri, Apr 12, 2019 at 01:14:54PM -0700, Atish Patra wrote:
> On 4/10/19 11:56 PM, Christoph Hellwig wrote:
> > Given that this option enables generic code (which you reuse for RISC-V
> > later in this series) please also move the config option to
> > mm/Kconfig, proabbly keyed off another ARCH_HAVE_DEBUG_TLBFLUSH
> > symbol that the architecture can select.
> >
>
> Sure.

And when you do that, instead of deleting the help text, make it
generic. Otherwise, there's no explanation anymore, how that option is
supposed to be used through tlb_flushall_shift.

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

2019-04-25 21:54:30

by Palmer Dabbelt

[permalink] [raw]
Subject: Re: [1/3] x86: Update DEBUG_TLBFLUSH options description.

On Wed, 10 Apr 2019 15:44:47 PDT (-0700), [email protected] wrote:
> CONFIG_DEBUG_TLBFLUSH was added in 'commit 3df3212f9722 ("x86/tlb: add
> tlb_flushall_shift knob into debugfs")' to support tlb_flushall_shift
> knob. The knob was removed in 'commit e9f4e0a9fe27 ("x86/mm: Rip out
> complicated, out-of-date, buggy TLB flushing")'. However, the debug
> option was never removed from Kconfig. It was reused in commit
> '9824cf9753ec ("mm: vmstats: tlb flush counters")' but the commit text was
> never updated accordingly.
>
> Update the Kconfig option description as per its current usage.
>
> Signed-off-by: Atish Patra <[email protected]>
> ---
> arch/x86/Kconfig.debug | 15 +++------------
> 1 file changed, 3 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
> index 15d0fbe27872..c1a48d4ffebb 100644
> --- a/arch/x86/Kconfig.debug
> +++ b/arch/x86/Kconfig.debug
> @@ -125,21 +125,12 @@ config DOUBLEFAULT
> hair.
>
> config DEBUG_TLBFLUSH
> - bool "Set upper limit of TLB entries to flush one-by-one"
> + bool "Save tlb flush statstics to vmstat"
> depends on DEBUG_KERNEL
> ---help---
>
> - X86-only for now.
> -
> - This option allows the user to tune the amount of TLB entries the
> - kernel flushes one-by-one instead of doing a full TLB flush. In
> - certain situations, the former is cheaper. This is controlled by the
> - tlb_flushall_shift knob under /sys/kernel/debug/x86. If you set it
> - to -1, the code flushes the whole TLB unconditionally. Otherwise,
> - for positive values of it, the kernel will use single TLB entry
> - invalidating instructions according to the following formula:
> -
> - flush_entries <= active_tlb_entries / 2^tlb_flushall_shift
> + Add tlbflush statstics to vmstat. It is really helpful understand tlbflush
> + performance and behavior. It should be enabled only for debugging purpose.
>
> If in doubt, say "N".

Reviewed-by: Palmer Dabbelt <[email protected]>

I'm not going to take this via my tree, but I'll look into the next two.

2019-04-26 00:34:42

by Palmer Dabbelt

[permalink] [raw]
Subject: Re: [2/3] RISC-V: Update tlb flush counters

On Wed, 10 Apr 2019 15:44:48 PDT (-0700), [email protected] wrote:
> The TLB flush counters under vmstat seems to be very helpful while
> debugging TLB flush performance in RISC-V.
>
> Update the counters in every TLB flush methods respectively.
>
> Signed-off-by: Atish Patra <[email protected]>
> ---
> arch/riscv/include/asm/tlbflush.h | 5 +++++
> arch/riscv/mm/tlbflush.c | 12 ++++++++++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> index 29a780ca232a..19779a083f52 100644
> --- a/arch/riscv/include/asm/tlbflush.h
> +++ b/arch/riscv/include/asm/tlbflush.h
> @@ -9,6 +9,7 @@
> #define _ASM_RISCV_TLBFLUSH_H
>
> #include <linux/mm_types.h>
> +#include <linux/vmstat.h>
>
> /*
> * Flush entire local TLB. 'sfence.vma' implicitly fences with the instruction
> @@ -16,11 +17,13 @@
> */
> static inline void local_flush_tlb_all(void)
> {
> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
> __asm__ __volatile__ ("sfence.vma" : : : "memory");
> }
>
> static inline void local_flush_tlb_mm(struct mm_struct *mm)
> {
> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
> /* Flush ASID 0 so that global mappings are not affected */
> __asm__ __volatile__ ("sfence.vma x0, %0" : : "r" (0) : "memory");
> }
> @@ -28,6 +31,7 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
> static inline void local_flush_tlb_page(struct vm_area_struct *vma,
> unsigned long addr)
> {
> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
> __asm__ __volatile__ ("sfence.vma %0, %1"
> : : "r" (addr), "r" (0)
> : "memory");
> @@ -35,6 +39,7 @@ static inline void local_flush_tlb_page(struct vm_area_struct *vma,
>
> static inline void local_flush_tlb_kernel_page(unsigned long addr)
> {
> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
> __asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory");
> }
>
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index ceee76f14a0a..8072d7da32bb 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -4,6 +4,8 @@
> */
>
> #include <linux/mm.h>
> +#include <linux/vmstat.h>
> +#include <linux/cpumask.h>
> #include <asm/sbi.h>
>
> #define SFENCE_VMA_FLUSH_ALL ((unsigned long) -1)
> @@ -110,6 +112,7 @@ static void ipi_remote_sfence_vma(void *info)
> unsigned long size = data->size;
> unsigned long i;
>
> + count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
> if (size == SFENCE_VMA_FLUSH_ALL) {
> local_flush_tlb_all();
> }
> @@ -129,6 +132,8 @@ static void ipi_remote_sfence_vma_asid(void *info)
> unsigned long size = data->size;
> unsigned long i;
>
> + count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
> + /* Flush entire MM context */
> if (size == SFENCE_VMA_FLUSH_ALL) {
> __asm__ __volatile__ ("sfence.vma x0, %0"
> : : "r" (asid)
> @@ -158,6 +163,13 @@ static void remote_sfence_vma(unsigned long start, unsigned long size)
> static void remote_sfence_vma_asid(cpumask_t *mask, unsigned long start,
> unsigned long size, unsigned long asid)
> {
> + int cpuid = smp_processor_id();
> +
> + if (cpumask_equal(mask, cpumask_of(cpuid)))
> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
> + else
> + count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
> +
> if (tlbi_ipi) {
> struct tlbi info = {
> .start = start,

Looks good, but it's not applying on for-next (based on rc6). Do you mind
re-spinning the patches?

2019-04-26 18:57:03

by Atish Patra

[permalink] [raw]
Subject: Re: [2/3] RISC-V: Update tlb flush counters

On 4/25/19 10:31 PM, Palmer Dabbelt wrote:
> On Wed, 10 Apr 2019 15:44:48 PDT (-0700), [email protected] wrote:
>> The TLB flush counters under vmstat seems to be very helpful while
>> debugging TLB flush performance in RISC-V.
>>
>> Update the counters in every TLB flush methods respectively.
>>
>> Signed-off-by: Atish Patra <[email protected]>
>> ---
>> arch/riscv/include/asm/tlbflush.h | 5 +++++
>> arch/riscv/mm/tlbflush.c | 12 ++++++++++++
>> 2 files changed, 17 insertions(+)
>>
>> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
>> index 29a780ca232a..19779a083f52 100644
>> --- a/arch/riscv/include/asm/tlbflush.h
>> +++ b/arch/riscv/include/asm/tlbflush.h
>> @@ -9,6 +9,7 @@
>> #define _ASM_RISCV_TLBFLUSH_H
>>
>> #include <linux/mm_types.h>
>> +#include <linux/vmstat.h>
>>
>> /*
>> * Flush entire local TLB. 'sfence.vma' implicitly fences with the instruction
>> @@ -16,11 +17,13 @@
>> */
>> static inline void local_flush_tlb_all(void)
>> {
>> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
>> __asm__ __volatile__ ("sfence.vma" : : : "memory");
>> }
>>
>> static inline void local_flush_tlb_mm(struct mm_struct *mm)
>> {
>> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
>> /* Flush ASID 0 so that global mappings are not affected */
>> __asm__ __volatile__ ("sfence.vma x0, %0" : : "r" (0) : "memory");
>> }
>> @@ -28,6 +31,7 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
>> static inline void local_flush_tlb_page(struct vm_area_struct *vma,
>> unsigned long addr)
>> {
>> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
>> __asm__ __volatile__ ("sfence.vma %0, %1"
>> : : "r" (addr), "r" (0)
>> : "memory");
>> @@ -35,6 +39,7 @@ static inline void local_flush_tlb_page(struct vm_area_struct *vma,
>>
>> static inline void local_flush_tlb_kernel_page(unsigned long addr)
>> {
>> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ONE);
>> __asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory");
>> }
>>
>> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
>> index ceee76f14a0a..8072d7da32bb 100644
>> --- a/arch/riscv/mm/tlbflush.c
>> +++ b/arch/riscv/mm/tlbflush.c
>> @@ -4,6 +4,8 @@
>> */
>>
>> #include <linux/mm.h>
>> +#include <linux/vmstat.h>
>> +#include <linux/cpumask.h>
>> #include <asm/sbi.h>
>>
>> #define SFENCE_VMA_FLUSH_ALL ((unsigned long) -1)
>> @@ -110,6 +112,7 @@ static void ipi_remote_sfence_vma(void *info)
>> unsigned long size = data->size;
>> unsigned long i;
>>
>> + count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
>> if (size == SFENCE_VMA_FLUSH_ALL) {
>> local_flush_tlb_all();
>> }
>> @@ -129,6 +132,8 @@ static void ipi_remote_sfence_vma_asid(void *info)
>> unsigned long size = data->size;
>> unsigned long i;
>>
>> + count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
>> + /* Flush entire MM context */
>> if (size == SFENCE_VMA_FLUSH_ALL) {
>> __asm__ __volatile__ ("sfence.vma x0, %0"
>> : : "r" (asid)
>> @@ -158,6 +163,13 @@ static void remote_sfence_vma(unsigned long start, unsigned long size)
>> static void remote_sfence_vma_asid(cpumask_t *mask, unsigned long start,
>> unsigned long size, unsigned long asid)
>> {
>> + int cpuid = smp_processor_id();
>> +
>> + if (cpumask_equal(mask, cpumask_of(cpuid)))
>> + count_vm_tlb_event(NR_TLB_LOCAL_FLUSH_ALL);
>> + else
>> + count_vm_tlb_event(NR_TLB_REMOTE_FLUSH);
>> +
>> if (tlbi_ipi) {
>> struct tlbi info = {
>> .start = start,
>
> Looks good, but it's not applying on for-next (based on rc6). Do you mind
> re-spinning the patches?
>
>

This patch depends is based on Gary's TLB flush patch series

https://patchwork.kernel.org/project/linux-riscv/list/?series=97315

So it should only be merged on top of it.

Regards,
Atish
> _______________________________________________
> linux-riscv mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-riscv
>

2019-04-29 19:59:42

by Atish Patra

[permalink] [raw]
Subject: Re: [1/3] x86: Update DEBUG_TLBFLUSH options description.

On 4/14/19 7:29 AM, Borislav Petkov wrote:
> On Fri, Apr 12, 2019 at 01:14:54PM -0700, Atish Patra wrote:
>> On 4/10/19 11:56 PM, Christoph Hellwig wrote:
>>> Given that this option enables generic code (which you reuse for RISC-V
>>> later in this series) please also move the config option to
>>> mm/Kconfig, proabbly keyed off another ARCH_HAVE_DEBUG_TLBFLUSH
>>> symbol that the architecture can select.
>>>
>>
>> Sure.
>
> And when you do that, instead of deleting the help text, make it
> generic. Otherwise, there's no explanation anymore, how that option is
> supposed to be used through tlb_flushall_shift.
>
Not sure I am following you.
tlb_flushall_shift knob was removed by
commit e9f4e0a9fe27 ("x86/mm: Rip out complicated, out-of-date, buggy
TLB flushing")


Regards,
Atish