Here are some optimizations and fixes to make CPU online/offline
faster and hence result in faster bootup.
Its based on top of my v5 coregroup support patchset.
https://lore.kernel.org/linuxppc-dev/[email protected]/t/#u
Anton reported that his 4096 cpu (1024 cores in a socket) was taking too
long to boot. He also analyzed that most of the time was being spent on
updating cpu_core_mask.
The first two patches should solve Anton's immediate problem.
On the unofficial patches, Anton reported that the boot time came from 30
mins to 6 seconds. (Basically a high core count in a single socket
configuration). Satheesh also reported similar numbers.
The rest are cleanups/optimizations.
Since cpu_core_mask is an exported symbol for a long duration, lets retain
as a snapshot of cpumask_of_node.
$ lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 1024
On-line CPU(s) list: 0-1023
Thread(s) per core: 8
Core(s) per socket: 8
Socket(s): 16
NUMA node(s): 16
Model: 2.0 (pvr 004d 0200)
Model name: POWER8 (architected), altivec supported
Hypervisor vendor: pHyp
Virtualization type: para
L1d cache: 64K
L1i cache: 32K
L2 cache: 512K
L3 cache: 8192K
NUMA node0 CPU(s): 0-63
NUMA node1 CPU(s): 64-127
NUMA node2 CPU(s): 128-191
NUMA node3 CPU(s): 192-255
NUMA node4 CPU(s): 256-319
NUMA node5 CPU(s): 320-383
NUMA node6 CPU(s): 384-447
NUMA node7 CPU(s): 448-511
NUMA node8 CPU(s): 512-575
NUMA node9 CPU(s): 576-639
NUMA node10 CPU(s): 640-703
NUMA node11 CPU(s): 704-767
NUMA node12 CPU(s): 768-831
NUMA node13 CPU(s): 832-895
NUMA node14 CPU(s): 896-959
NUMA node15 CPU(s): 960-1023
$ dmesg -k | grep -i -e Bringing -e Brought -e sysrq -e bug
With powerp/next
[ 0.000000] printk: debug: ignoring loglevel setting.
[ 0.354971] smp: Bringing up secondary CPUs ...
[ 233.354676] smp: Brought up 16 nodes, 1024 CPUs
[ 330.023073] sysrq: Changing Loglevel
[ 330.023101] sysrq: Loglevel set to 9
With +patchset
[ 0.000000] printk: debug: ignoring loglevel setting.
[ 0.351703] smp: Bringing up secondary CPUs ...
[ 4.059859] smp: Brought up 16 nodes, 1024 CPUs
[ 98.309015] sysrq: Changing Loglevel
[ 98.309044] sysrq: Loglevel set to 9
Observations:
CPU bringup time reduced to 4 seconds from 233 seconds on this 1024 CPU
system. This resulted in System boot up time reducing to 98 seconds from
330 seconds. The actual improvement would depend on your system topology.
Topology verification post patchset on a 2 node Power9 PowerVM LPAR
powerpc/next +patchset
------------ ---------
$ lscpu
Architecture: ppc64le Architecture: ppc64le
Byte Order: Little Endian Byte Order: Little Endian
CPU(s): 128 CPU(s): 128
On-line CPU(s) list: 0-127 On-line CPU(s) list: 0-127
Thread(s) per core: 8 Thread(s) per core: 8
Core(s) per socket: 8 Core(s) per socket: 8
Socket(s): 2 Socket(s): 2
NUMA node(s): 2 NUMA node(s): 2
Model: 2.2 (pvr 004e 0202) Model: 2.2 (pvr 004e 0202)
Model name: POWER9 (architected), altivec supported Model name: POWER9 (architected), altivec supported
Hypervisor vendor: pHyp Hypervisor vendor: pHyp
Virtualization type: para Virtualization type: para
L1d cache: 32K L1d cache: 32K
L1i cache: 32K L1i cache: 32K
L2 cache: 512K L2 cache: 512K
L3 cache: 10240K L3 cache: 10240K
NUMA node0 CPU(s): 0-63 NUMA node0 CPU(s): 0-63
NUMA node1 CPU(s): 64-127 NUMA node1 CPU(s): 64-127
$ tail -f /proc/cpuinfo
processor : 127 processor : 127
cpu : POWER9 (architected), altivec supported cpu : POWER9 (architected), altivec supported
clock : 3000.000000MHz clock : 3000.000000MHz
revision : 2.2 (pvr 004e 0202) revision : 2.2 (pvr 004e 0202)
timebase : 512000000 timebase : 512000000
platform : pSeries platform : pSeries
model : IBM,9008-22L model : IBM,9008-22L
machine : CHRP IBM,9008-22L machine : CHRP IBM,9008-22L
MMU : Radix MMU : Radix
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/name
--------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/name:SMT /proc/sys/kernel/sched_domain/cpu0/domain0/name:SMT
/proc/sys/kernel/sched_domain/cpu0/domain1/name:CACHE /proc/sys/kernel/sched_domain/cpu0/domain1/name:CACHE
/proc/sys/kernel/sched_domain/cpu0/domain2/name:DIE /proc/sys/kernel/sched_domain/cpu0/domain2/name:DIE
/proc/sys/kernel/sched_domain/cpu0/domain3/name:NUMA /proc/sys/kernel/sched_domain/cpu0/domain3/name:NUMA
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/flags
---------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/flags:2391 /proc/sys/kernel/sched_domain/cpu0/domain0/flags:2391
/proc/sys/kernel/sched_domain/cpu0/domain1/flags:2327 /proc/sys/kernel/sched_domain/cpu0/domain1/flags:2327
/proc/sys/kernel/sched_domain/cpu0/domain2/flags:2071 /proc/sys/kernel/sched_domain/cpu0/domain2/flags:2071
/proc/sys/kernel/sched_domain/cpu0/domain3/flags:12801 /proc/sys/kernel/sched_domain/cpu0/domain3/flags:12801
Post ppc64_cpu --smt=1
$ tail -f /proc/cpuinfo
processor : 120 processor : 120
cpu : POWER9 (architected), altivec supported cpu : POWER9 (architected), altivec supported
clock : 3000.000000MHz clock : 3000.000000MHz
revision : 2.2 (pvr 004e 0202) revision : 2.2 (pvr 004e 0202)
timebase : 512000000 timebase : 512000000
platform : pSeries platform : pSeries
model : IBM,9008-22L model : IBM,9008-22L
machine : CHRP IBM,9008-22L machine : CHRP IBM,9008-22L
MMU : Radix MMU : Radix
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/name
--------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/name:DIE /proc/sys/kernel/sched_domain/cpu0/domain0/name:DIE
/proc/sys/kernel/sched_domain/cpu0/domain1/name:NUMA /proc/sys/kernel/sched_domain/cpu0/domain1/name:NUMA
$ grep . /proc/sys/kernel/sched_domain/cpu0/domain*/flags
---------------------------------------------------------
/proc/sys/kernel/sched_domain/cpu0/domain0/flags:2071 /proc/sys/kernel/sched_domain/cpu0/domain0/flags:2071
/proc/sys/kernel/sched_domain/cpu0/domain1/flags:12801 /proc/sys/kernel/sched_domain/cpu0/domain1/flags:12801
Performance impact post +patchset
---------------------------------
100 iterations of ebizzy
Units: Records/second : higher is better
-----------------------------------------
kernel N Min Max Median Avg Stddev
powerpc/next 100 753917 870520 819054 817636.56 22649.7
+patchset 100 746258 874984 816681 813876.74 26424.351
100 iterations of perf bench sched pipe -l 10000000 (aka Hackbench)
units: usec/ops: lesser is better
--------------------------------
kernel N Min Max Median Avg Stddev
powerpc/next 100 13.845834 14.569539 14.06263 14.086167 0.17512607
+patchset 100 13.637611 18.097744 13.862656 13.9257 0.43872453
schbench Latency percentiles (usec)
units: usec : lesser is better
-----------------------------------
powerpc/next +patchset
50.0000th: 48 50.0000th: 49
75.0000th: 65 75.0000th: 66
90.0000th: 77 90.0000th: 79
95.0000th: 84 95.0000th: 85
*99.0000th: 101 *99.0000th: 99
99.5000th: 113 99.5000th: 104
99.9000th: 159 99.9000th: 129
min=0, max=15221 min=0, max=7666
100 interations of ppc64_cpu --smt=1 / ppc64_cpu --smt=8
Units: seconds : lesser is better
---------------------------------
ppc64_cpu --smt=1
kernel N Min Max Median Avg Stddev
powerpc/next 100 13.39 17.55 14.71 14.7658 0.69184745
+patchset 100 13.3 16.27 14.33 14.4179 0.5427433
ppc64_cpu --smt=8
kernel N Min Max Median Avg Stddev
powerpc/next 100 21.65 26.17 23.71 23.7111 0.8589786
+patchset 100 21.88 25.79 23.16 23.2945 0.86394839
Observations:
Performance of ebizzy/ perf_sched_bench / schbench remain the
same with and without the patchset.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Changelog v1->v2:
v1 link: https://lore.kernel.org/linuxppc-dev/[email protected]/t/#u
Added five more patches on top of Seven.
Rebased to 19th Sept 2020 powerpc/next (based on v5.9-rc2)
Srikar Dronamraju (11):
powerpc/topology: Update topology_core_cpumask
powerpc/smp: Stop updating cpu_core_mask
powerpc/smp: Remove get_physical_package_id
powerpc/smp: Optimize remove_cpu_from_masks
powerpc/smp: Limit CPUs traversed to within a node.
powerpc/smp: Stop passing mask to update_mask_by_l2
powerpc/smp: Depend on cpu_l1_cache_map when adding CPUs
powerpc/smp: Check for duplicate topologies and consolidate
powerpc/smp: Optimize update_mask_by_l2
powerpc/smp: Move coregroup mask updation to a new function
powerpc/smp: Optimize update_coregroup_mask
arch/powerpc/include/asm/smp.h | 5 -
arch/powerpc/include/asm/topology.h | 7 +-
arch/powerpc/kernel/smp.c | 186 ++++++++++++++++++----------
3 files changed, 120 insertions(+), 78 deletions(-)
--
2.17.1
On Power, cpu_core_mask and cpu_cpu_mask refer to the same set of CPUs.
cpu_cpu_mask is needed by scheduler, hence look at deprecating
cpu_core_mask. Before deleting the cpu_core_mask, ensure its only user
is moved to cpu_cpu_mask.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/include/asm/topology.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index 6609174918ab..e0f232533c9d 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -122,7 +122,7 @@ int get_physical_package_id(int cpu);
#endif
#define topology_sibling_cpumask(cpu) (per_cpu(cpu_sibling_map, cpu))
-#define topology_core_cpumask(cpu) (per_cpu(cpu_core_map, cpu))
+#define topology_core_cpumask(cpu) (cpu_cpu_mask(cpu))
#define topology_core_id(cpu) (cpu_to_core_id(cpu))
#endif
--
2.17.1
Now that cpu_core_mask has been removed and topology_core_cpumask has
been updated to use cpu_cpu_mask, we no more need
get_physical_package_id.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/include/asm/topology.h | 5 -----
arch/powerpc/kernel/smp.c | 20 --------------------
2 files changed, 25 deletions(-)
diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index e0f232533c9d..e45219f74be0 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -114,12 +114,7 @@ static inline int cpu_to_coregroup_id(int cpu)
#ifdef CONFIG_PPC64
#include <asm/smp.h>
-#ifdef CONFIG_PPC_SPLPAR
-int get_physical_package_id(int cpu);
-#define topology_physical_package_id(cpu) (get_physical_package_id(cpu))
-#else
#define topology_physical_package_id(cpu) (cpu_to_chip_id(cpu))
-#endif
#define topology_sibling_cpumask(cpu) (per_cpu(cpu_sibling_map, cpu))
#define topology_core_cpumask(cpu) (cpu_cpu_mask(cpu))
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index ec41491beca4..8c095fe237b2 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1292,26 +1292,6 @@ static inline void add_cpu_to_smallcore_masks(int cpu)
}
}
-int get_physical_package_id(int cpu)
-{
- int pkg_id = cpu_to_chip_id(cpu);
-
- /*
- * If the platform is PowerNV or Guest on KVM, ibm,chip-id is
- * defined. Hence we would return the chip-id as the result of
- * get_physical_package_id.
- */
- if (pkg_id == -1 && firmware_has_feature(FW_FEATURE_LPAR) &&
- IS_ENABLED(CONFIG_PPC_SPLPAR)) {
- struct device_node *np = of_get_cpu_node(cpu, NULL);
- pkg_id = of_node_to_nid(np);
- of_node_put(np);
- }
-
- return pkg_id;
-}
-EXPORT_SYMBOL_GPL(get_physical_package_id);
-
static void add_cpu_to_masks(int cpu)
{
int first_thread = cpu_first_thread_sibling(cpu);
--
2.17.1
Anton Blanchard reported that his 4096 vcpu KVM guest took around 30
minutes to boot. He also analyzed it to the time taken to iterate while
setting the cpu_core_mask.
Further analysis shows that cpu_core_mask and cpu_cpu_mask for any CPU
would be equal on Power. However updating cpu_core_mask took forever to
update as its a per cpu cpumask variable. Instead cpu_cpu_mask was a per
NODE /per DIE cpumask that was shared by all the respective CPUs.
Also cpu_cpu_mask is needed from a scheduler perspective. However
cpu_core_map is an exported symbol. Hence stop updating cpu_core_map
and make it point to cpu_cpu_mask.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/include/asm/smp.h | 5 -----
arch/powerpc/kernel/smp.c | 33 +++++++--------------------------
2 files changed, 7 insertions(+), 31 deletions(-)
diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 041f0b97c45b..40e121dd16af 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -119,11 +119,6 @@ static inline struct cpumask *cpu_sibling_mask(int cpu)
return per_cpu(cpu_sibling_map, cpu);
}
-static inline struct cpumask *cpu_core_mask(int cpu)
-{
- return per_cpu(cpu_core_map, cpu);
-}
-
static inline struct cpumask *cpu_l2_cache_mask(int cpu)
{
return per_cpu(cpu_l2_cache_map, cpu);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 3d96752d6570..ec41491beca4 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -953,12 +953,17 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
local_memory_node(numa_cpu_lookup_table[cpu]));
}
#endif
+ /*
+ * cpu_core_map is now more updated and exists only since
+ * its been exported for long. It only will have a snapshot
+ * of cpu_cpu_mask.
+ */
+ cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu));
}
/* Init the cpumasks so the boot CPU is related to itself */
cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
cpumask_set_cpu(boot_cpuid, cpu_l2_cache_mask(boot_cpuid));
- cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
if (has_coregroup_support())
cpumask_set_cpu(boot_cpuid, cpu_coregroup_mask(boot_cpuid));
@@ -1260,9 +1265,7 @@ static void remove_cpu_from_masks(int cpu)
{
int i;
- /* NB: cpu_core_mask is a superset of the others */
- for_each_cpu(i, cpu_core_mask(cpu)) {
- set_cpus_unrelated(cpu, i, cpu_core_mask);
+ for_each_cpu(i, cpu_cpu_mask(cpu)) {
set_cpus_unrelated(cpu, i, cpu_l2_cache_mask);
set_cpus_unrelated(cpu, i, cpu_sibling_mask);
if (has_big_cores)
@@ -1312,7 +1315,6 @@ EXPORT_SYMBOL_GPL(get_physical_package_id);
static void add_cpu_to_masks(int cpu)
{
int first_thread = cpu_first_thread_sibling(cpu);
- int pkg_id = get_physical_package_id(cpu);
int i;
/*
@@ -1320,7 +1322,6 @@ static void add_cpu_to_masks(int cpu)
* add it to it's own thread sibling mask.
*/
cpumask_set_cpu(cpu, cpu_sibling_mask(cpu));
- cpumask_set_cpu(cpu, cpu_core_mask(cpu));
for (i = first_thread; i < first_thread + threads_per_core; i++)
if (cpu_online(i))
@@ -1342,26 +1343,6 @@ static void add_cpu_to_masks(int cpu)
set_cpus_related(cpu, i, cpu_coregroup_mask);
}
}
-
- if (pkg_id == -1) {
- struct cpumask *(*mask)(int) = cpu_sibling_mask;
-
- /*
- * Copy the sibling mask into core sibling mask and
- * mark any CPUs on the same chip as this CPU.
- */
- if (shared_caches)
- mask = cpu_l2_cache_mask;
-
- for_each_cpu(i, mask(cpu))
- set_cpus_related(cpu, i, cpu_core_mask);
-
- return;
- }
-
- for_each_cpu(i, cpu_online_mask)
- if (get_physical_package_id(i) == pkg_id)
- set_cpus_related(cpu, i, cpu_core_mask);
}
/* Activate a secondary processor. */
--
2.17.1
All the arch specific topology cpumasks are within a node/DIE.
However when setting these per CPU cpumasks, system traverses through
all the online CPUs. This is redundant.
Reduce the traversal to only CPUs that are online in the node to which
the CPU belongs to.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/kernel/smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 2e61a81aad88..c860c4950c9f 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1241,7 +1241,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
}
cpumask_set_cpu(cpu, mask_fn(cpu));
- for_each_cpu(i, cpu_online_mask) {
+ for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
/*
* when updating the marks the current CPU has not been marked
* online, but we need to update the cache masks
--
2.17.1
Currently on hotplug/hotunplug, CPU iterates through all the CPUs in
its core to find threads in its thread group. However this info is
already captured in cpu_l1_cache_map. Hence reduce iterations and
cleanup add_cpu_to_smallcore_masks function.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/kernel/smp.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 441c9c64b1e3..aeb219a4bf7a 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1285,16 +1285,15 @@ static void remove_cpu_from_masks(int cpu)
static inline void add_cpu_to_smallcore_masks(int cpu)
{
- struct cpumask *this_l1_cache_map = per_cpu(cpu_l1_cache_map, cpu);
- int i, first_thread = cpu_first_thread_sibling(cpu);
+ int i;
if (!has_big_cores)
return;
cpumask_set_cpu(cpu, cpu_smallcore_mask(cpu));
- for (i = first_thread; i < first_thread + threads_per_core; i++) {
- if (cpu_online(i) && cpumask_test_cpu(i, this_l1_cache_map))
+ for_each_cpu(i, per_cpu(cpu_l1_cache_map, cpu)) {
+ if (cpu_online(i))
set_cpus_related(i, cpu, cpu_smallcore_mask);
}
}
--
2.17.1
All threads of a SMT4 core can either be part of this CPU's l2-cache
mask or not related to this CPU l2-cache mask. Use this relation to
reduce the number of iterations needed to find all the CPUs that share
the same l2-cache.
Use a temporary mask to iterate through the CPUs that may share l2_cache
mask. Also instead of setting one CPU at a time into cpu_l2_cache_mask,
copy the SMT4/sub mask at one shot.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
arch/powerpc/kernel/smp.c | 51 ++++++++++++++++++++++++++++++++++-----
1 file changed, 45 insertions(+), 6 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 6f866e6b12f8..17e90c2414af 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -670,6 +670,28 @@ static void set_cpus_unrelated(int i, int j,
}
#endif
+/*
+ * Extends set_cpus_related. Instead of setting one CPU at a time in
+ * dstmask, set srcmask at oneshot. dstmask should be super set of srcmask.
+ */
+static void or_cpumasks_related(int i, int j, struct cpumask *(*srcmask)(int),
+ struct cpumask *(*dstmask)(int))
+{
+ struct cpumask *mask;
+ int k;
+
+ mask = srcmask(j);
+ for_each_cpu(k, srcmask(i))
+ cpumask_or(dstmask(k), dstmask(k), mask);
+
+ if (i == j)
+ return;
+
+ mask = srcmask(i);
+ for_each_cpu(k, srcmask(j))
+ cpumask_or(dstmask(k), dstmask(k), mask);
+}
+
/*
* parse_thread_groups: Parses the "ibm,thread-groups" device tree
* property for the CPU device node @dn and stores
@@ -1220,7 +1242,9 @@ static struct device_node *cpu_to_l2cache(int cpu)
static bool update_mask_by_l2(int cpu)
{
+ struct cpumask *(*submask_fn)(int) = cpu_sibling_mask;
struct device_node *l2_cache, *np;
+ cpumask_var_t mask;
int i;
l2_cache = cpu_to_l2cache(cpu);
@@ -1240,22 +1264,37 @@ static bool update_mask_by_l2(int cpu)
return false;
}
- cpumask_set_cpu(cpu, cpu_l2_cache_mask(cpu));
- for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
+ alloc_cpumask_var_node(&mask, GFP_KERNEL, cpu_to_node(cpu));
+ cpumask_and(mask, cpu_online_mask, cpu_cpu_mask(cpu));
+
+ if (has_big_cores)
+ submask_fn = cpu_smallcore_mask;
+
+ /* Update l2-cache mask with all the CPUs that are part of submask */
+ or_cpumasks_related(cpu, cpu, submask_fn, cpu_l2_cache_mask);
+
+ /* Skip all CPUs already part of current CPU l2-cache mask */
+ cpumask_andnot(mask, mask, cpu_l2_cache_mask(cpu));
+
+ for_each_cpu(i, mask) {
/*
* when updating the marks the current CPU has not been marked
* online, but we need to update the cache masks
*/
np = cpu_to_l2cache(i);
- if (!np)
- continue;
- if (np == l2_cache)
- set_cpus_related(cpu, i, cpu_l2_cache_mask);
+ /* Skip all CPUs already part of current CPU l2-cache */
+ if (np == l2_cache) {
+ or_cpumasks_related(cpu, i, submask_fn, cpu_l2_cache_mask);
+ cpumask_andnot(mask, mask, submask_fn(i));
+ } else {
+ cpumask_andnot(mask, mask, cpu_l2_cache_mask(i));
+ }
of_node_put(np);
}
of_node_put(l2_cache);
+ free_cpumask_var(mask);
return true;
}
--
2.17.1
CACHE and COREGROUP domains are now part of default topology. However on
systems that don't support CACHE or COREGROUP, these domains will
eventually be degenerated. The degeneration happens per CPU. Do note the
current fixup_topology() logic ensures that mask of a domain that is not
supported on the current platform is set to the previous domain.
Instead of waiting for the scheduler to degenerated try to consolidate
based on their masks and sd_flags. This is done just before setting
the scheduler topology.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
arch/powerpc/kernel/smp.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index aeb219a4bf7a..6f866e6b12f8 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1401,6 +1401,8 @@ int setup_profiling_timer(unsigned int multiplier)
static void fixup_topology(void)
{
+ int i;
+
#ifdef CONFIG_SCHED_SMT
if (has_big_cores) {
pr_info("Big cores detected but using small core scheduling\n");
@@ -1410,6 +1412,30 @@ static void fixup_topology(void)
if (!has_coregroup_support())
powerpc_topology[mc_idx].mask = powerpc_topology[cache_idx].mask;
+
+ /*
+ * Try to consolidate topology levels here instead of
+ * allowing scheduler to degenerate.
+ * - Dont consolidate if masks are different.
+ * - Dont consolidate if sd_flags exists and are different.
+ */
+ for (i = 1; i <= die_idx; i++) {
+ if (powerpc_topology[i].mask != powerpc_topology[i - 1].mask)
+ continue;
+
+ if (powerpc_topology[i].sd_flags && powerpc_topology[i - 1].sd_flags &&
+ powerpc_topology[i].sd_flags != powerpc_topology[i - 1].sd_flags)
+ continue;
+
+ if (!powerpc_topology[i - 1].sd_flags)
+ powerpc_topology[i - 1].sd_flags = powerpc_topology[i].sd_flags;
+
+ powerpc_topology[i].mask = powerpc_topology[i + 1].mask;
+ powerpc_topology[i].sd_flags = powerpc_topology[i + 1].sd_flags;
+#ifdef CONFIG_SCHED_DEBUG
+ powerpc_topology[i].name = powerpc_topology[i + 1].name;
+#endif
+ }
}
void __init smp_cpus_done(unsigned int max_cpus)
--
2.17.1
Move the logic for updating the coregroup mask of a CPU to its own
function. This will help in reworking the updation of coregroup mask in
subsequent patch.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
arch/powerpc/kernel/smp.c | 32 +++++++++++++++++++-------------
1 file changed, 19 insertions(+), 13 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 17e90c2414af..b48ae4e306d3 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1337,6 +1337,23 @@ static inline void add_cpu_to_smallcore_masks(int cpu)
}
}
+static void update_coregroup_mask(int cpu)
+{
+ int first_thread = cpu_first_thread_sibling(cpu);
+ int coregroup_id = cpu_to_coregroup_id(cpu);
+ int i;
+
+ cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu));
+ for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
+ int fcpu = cpu_first_thread_sibling(i);
+
+ if (fcpu == first_thread)
+ set_cpus_related(cpu, i, cpu_coregroup_mask);
+ else if (coregroup_id == cpu_to_coregroup_id(i))
+ set_cpus_related(cpu, i, cpu_coregroup_mask);
+ }
+}
+
static void add_cpu_to_masks(int cpu)
{
int first_thread = cpu_first_thread_sibling(cpu);
@@ -1355,19 +1372,8 @@ static void add_cpu_to_masks(int cpu)
add_cpu_to_smallcore_masks(cpu);
update_mask_by_l2(cpu);
- if (has_coregroup_support()) {
- int coregroup_id = cpu_to_coregroup_id(cpu);
-
- cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu));
- for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
- int fcpu = cpu_first_thread_sibling(i);
-
- if (fcpu == first_thread)
- set_cpus_related(cpu, i, cpu_coregroup_mask);
- else if (coregroup_id == cpu_to_coregroup_id(i))
- set_cpus_related(cpu, i, cpu_coregroup_mask);
- }
- }
+ if (has_coregroup_support())
+ update_coregroup_mask(cpu);
}
/* Activate a secondary processor. */
--
2.17.1
All threads of a SMT4/SMT8 core can either be part of CPU's coregroup
mask or outside the coregroup. Use this relation to reduce the
number of iterations needed to find all the CPUs that share the same
coregroup
Use a temporary mask to iterate through the CPUs that may share
coregroup mask. Also instead of setting one CPU at a time into
cpu_coregroup_mask, copy the SMT4/SMT8/submask at one shot.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
---
arch/powerpc/kernel/smp.c | 30 ++++++++++++++++++++++--------
1 file changed, 22 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index b48ae4e306d3..bbaea93dc558 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1339,19 +1339,33 @@ static inline void add_cpu_to_smallcore_masks(int cpu)
static void update_coregroup_mask(int cpu)
{
- int first_thread = cpu_first_thread_sibling(cpu);
+ struct cpumask *(*submask_fn)(int) = cpu_sibling_mask;
+ cpumask_var_t mask;
int coregroup_id = cpu_to_coregroup_id(cpu);
int i;
- cpumask_set_cpu(cpu, cpu_coregroup_mask(cpu));
- for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
- int fcpu = cpu_first_thread_sibling(i);
+ alloc_cpumask_var_node(&mask, GFP_KERNEL, cpu_to_node(cpu));
+ cpumask_and(mask, cpu_online_mask, cpu_cpu_mask(cpu));
+
+ if (shared_caches)
+ submask_fn = cpu_l2_cache_mask;
+
+ /* Update coregroup mask with all the CPUs that are part of submask */
+ or_cpumasks_related(cpu, cpu, submask_fn, cpu_coregroup_mask);
+
+ /* Skip all CPUs already part of coregroup mask */
+ cpumask_andnot(mask, mask, cpu_coregroup_mask(cpu));
- if (fcpu == first_thread)
- set_cpus_related(cpu, i, cpu_coregroup_mask);
- else if (coregroup_id == cpu_to_coregroup_id(i))
- set_cpus_related(cpu, i, cpu_coregroup_mask);
+ for_each_cpu(i, mask) {
+ /* Skip all CPUs not part of this coregroup */
+ if (coregroup_id == cpu_to_coregroup_id(i)) {
+ or_cpumasks_related(cpu, i, submask_fn, cpu_coregroup_mask);
+ cpumask_andnot(mask, mask, submask_fn(i));
+ } else {
+ cpumask_andnot(mask, mask, cpu_coregroup_mask(i));
+ }
}
+ free_cpumask_var(mask);
}
static void add_cpu_to_masks(int cpu)
--
2.17.1
While offlining a CPU, system currently iterate through all the CPUs in
the DIE to clear sibling, l2_cache and smallcore maps. However if there
are more cores in a DIE, system can end up spending more time iterating
through CPUs which are completely unrelated.
Optimize this by only iterating through smaller but relevant cpumap.
If shared_cache is set, cpu_l2_cache_map should be relevant else
cpu_sibling_map would be relevant.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/kernel/smp.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 8c095fe237b2..2e61a81aad88 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1263,14 +1263,21 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
#ifdef CONFIG_HOTPLUG_CPU
static void remove_cpu_from_masks(int cpu)
{
+ struct cpumask *(*mask_fn)(int) = cpu_sibling_mask;
int i;
- for_each_cpu(i, cpu_cpu_mask(cpu)) {
+ if (shared_caches)
+ mask_fn = cpu_l2_cache_mask;
+
+ for_each_cpu(i, mask_fn(cpu)) {
set_cpus_unrelated(cpu, i, cpu_l2_cache_mask);
set_cpus_unrelated(cpu, i, cpu_sibling_mask);
if (has_big_cores)
set_cpus_unrelated(cpu, i, cpu_smallcore_mask);
- if (has_coregroup_support())
+ }
+
+ if (has_coregroup_support()) {
+ for_each_cpu(i, cpu_coregroup_mask(cpu))
set_cpus_unrelated(cpu, i, cpu_coregroup_mask);
}
}
--
2.17.1
update_mask_by_l2 is called only once. But it passes cpu_l2_cache_mask
as parameter. Instead of passing cpu_l2_cache_mask, use it directly in
update_mask_by_l2.
Cc: linuxppc-dev <[email protected]>
Cc: LKML <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Anton Blanchard <[email protected]>
Cc: Oliver O'Halloran <[email protected]>
Cc: Nathan Lynch <[email protected]>
Cc: Michael Neuling <[email protected]>
Cc: Gautham R Shenoy <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Valentin Schneider <[email protected]>
Signed-off-by: Srikar Dronamraju <[email protected]>
Tested-by: Satheesh Rajendran <[email protected]>
---
arch/powerpc/kernel/smp.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index c860c4950c9f..441c9c64b1e3 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1218,7 +1218,7 @@ static struct device_node *cpu_to_l2cache(int cpu)
return cache;
}
-static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
+static bool update_mask_by_l2(int cpu)
{
struct device_node *l2_cache, *np;
int i;
@@ -1240,7 +1240,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
return false;
}
- cpumask_set_cpu(cpu, mask_fn(cpu));
+ cpumask_set_cpu(cpu, cpu_l2_cache_mask(cpu));
for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
/*
* when updating the marks the current CPU has not been marked
@@ -1251,7 +1251,7 @@ static bool update_mask_by_l2(int cpu, struct cpumask *(*mask_fn)(int))
continue;
if (np == l2_cache)
- set_cpus_related(cpu, i, mask_fn);
+ set_cpus_related(cpu, i, cpu_l2_cache_mask);
of_node_put(np);
}
@@ -1315,7 +1315,7 @@ static void add_cpu_to_masks(int cpu)
set_cpus_related(i, cpu, cpu_sibling_mask);
add_cpu_to_smallcore_masks(cpu);
- update_mask_by_l2(cpu, cpu_l2_cache_mask);
+ update_mask_by_l2(cpu);
if (has_coregroup_support()) {
int coregroup_id = cpu_to_coregroup_id(cpu);
--
2.17.1
On Mon, 21 Sep 2020 15:26:42 +0530, Srikar Dronamraju wrote:
> Here are some optimizations and fixes to make CPU online/offline
> faster and hence result in faster bootup.
>
> Its based on top of my v5 coregroup support patchset.
> https://lore.kernel.org/linuxppc-dev/[email protected]/t/#u
>
> Anton reported that his 4096 cpu (1024 cores in a socket) was taking too
> long to boot. He also analyzed that most of the time was being spent on
> updating cpu_core_mask.
>
> [...]
Applied to powerpc/next.
[01/11] powerpc/topology: Update topology_core_cpumask
https://git.kernel.org/powerpc/c/4bce545903fa0290e011cf118997717f0c4f4d20
[02/11] powerpc/smp: Stop updating cpu_core_mask
https://git.kernel.org/powerpc/c/4ca234a9cbd7c3a656b34dd98c8b156f70ed7849
[03/11] powerpc/smp: Remove get_physical_package_id
https://git.kernel.org/powerpc/c/e29e9ed665eeb6f98cd88672994ecf4aaefdb943
[04/11] powerpc/smp: Optimize remove_cpu_from_masks
https://git.kernel.org/powerpc/c/70edd4a7c753ba18e3e4bb9e97b6d85156cea738
[05/11] powerpc/smp: Limit CPUs traversed to within a node.
https://git.kernel.org/powerpc/c/53516d4abacfab1faaa075c1f79957abc3da358c
[06/11] powerpc/smp: Stop passing mask to update_mask_by_l2
https://git.kernel.org/powerpc/c/1f3a4181042107e32e44047e9dde990aced845b5
[07/11] powerpc/smp: Depend on cpu_l1_cache_map when adding CPUs
https://git.kernel.org/powerpc/c/661e3d42f99193b7fdd71467a87e48f6e597c285
[08/11] powerpc/smp: Check for duplicate topologies and consolidate
https://git.kernel.org/powerpc/c/375370a10d061d5c75c6bc5b09c5db4cc0b0fcfe
[09/11] powerpc/smp: Optimize update_mask_by_l2
https://git.kernel.org/powerpc/c/3ab33d6dc3e98e83b55732049e1d1d488207bb6d
[10/11] powerpc/smp: Move coregroup mask updation to a new function
https://git.kernel.org/powerpc/c/b8a97cb4599cda28bd3b3bc13042f5803b42ad65
[11/11] powerpc/smp: Optimize update_coregroup_mask
https://git.kernel.org/powerpc/c/70a94089d7f7fa91bc1795622426b3ed017ec71a
cheers
On Mon, 2020-09-21 at 15:26 +0530, Srikar Dronamraju wrote:
> All threads of a SMT4 core can either be part of this CPU's l2-cache
> mask or not related to this CPU l2-cache mask. Use this relation to
> reduce the number of iterations needed to find all the CPUs that share
> the same l2-cache.
>
> Use a temporary mask to iterate through the CPUs that may share l2_cache
> mask. Also instead of setting one CPU at a time into cpu_l2_cache_mask,
> copy the SMT4/sub mask at one shot.
>
...
> static bool update_mask_by_l2(int cpu)
> {
> + struct cpumask *(*submask_fn)(int) = cpu_sibling_mask;
> struct device_node *l2_cache, *np;
> + cpumask_var_t mask;
> int i;
>
> l2_cache = cpu_to_l2cache(cpu);
> @@ -1240,22 +1264,37 @@ static bool update_mask_by_l2(int cpu)
> return false;
> }
>
> - cpumask_set_cpu(cpu, cpu_l2_cache_mask(cpu));
> - for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
> + alloc_cpumask_var_node(&mask, GFP_KERNEL, cpu_to_node(cpu));
Shouldn't this be GFP_ATOMIC? Otherwise, during the CPU hotplugging, we have,
(irqs were disabled in do_idle())
[ 335.420001][ T0] BUG: sleeping function called from invalid context at mm/slab.h:494
[ 335.420003][ T0] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/88
[ 335.420005][ T0] no locks held by swapper/88/0.
[ 335.420007][ T0] irq event stamp: 18074448
[ 335.420015][ T0] hardirqs last enabled at (18074447): [<c0000000001a2a7c>] tick_nohz_idle_enter+0x9c/0x110
[ 335.420019][ T0] hardirqs last disabled at (18074448): [<c000000000106798>] do_idle+0x138/0x3b0
do_idle at kernel/sched/idle.c:253 (discriminator 1)
[ 335.420023][ T0] softirqs last enabled at (18074440): [<c0000000000bbec4>] irq_enter_rcu+0x94/0xa0
[ 335.420026][ T0] softirqs last disabled at (18074439): [<c0000000000bbea0>] irq_enter_rcu+0x70/0xa0
[ 335.420030][ T0] CPU: 88 PID: 0 Comm: swapper/88 Tainted: G W 5.9.0-rc8-next-20201007 #1
[ 335.420032][ T0] Call Trace:
[ 335.420037][ T0] [c00020000a4bfcf0] [c000000000649e98] dump_stack+0xec/0x144 (unreliable)
[ 335.420043][ T0] [c00020000a4bfd30] [c0000000000f6c34] ___might_sleep+0x2f4/0x310
[ 335.420048][ T0] [c00020000a4bfdb0] [c000000000354f94] slab_pre_alloc_hook.constprop.82+0x124/0x190
[ 335.420051][ T0] [c00020000a4bfe00] [c00000000035e9e8] __kmalloc_node+0x88/0x3a0
slab_alloc_node at mm/slub.c:2817
(inlined by) __kmalloc_node at mm/slub.c:4013
[ 335.420054][ T0] [c00020000a4bfe80] [c0000000006494d8] alloc_cpumask_var_node+0x38/0x80
kmalloc_node at include/linux/slab.h:577
(inlined by) alloc_cpumask_var_node at lib/cpumask.c:116
[ 335.420060][ T0] [c00020000a4bfef0] [c00000000003eedc] start_secondary+0x27c/0x800
update_mask_by_l2 at arch/powerpc/kernel/smp.c:1267
(inlined by) add_cpu_to_masks at arch/powerpc/kernel/smp.c:1387
(inlined by) start_secondary at arch/powerpc/kernel/smp.c:1420
[ 335.420063][ T0] [c00020000a4bff90] [c00000000000c468] start_secondary_resume+0x10/0x14
> + cpumask_and(mask, cpu_online_mask, cpu_cpu_mask(cpu));
> +
> + if (has_big_cores)
> + submask_fn = cpu_smallcore_mask;
> +
> + /* Update l2-cache mask with all the CPUs that are part of submask */
> + or_cpumasks_related(cpu, cpu, submask_fn, cpu_l2_cache_mask);
> +
> + /* Skip all CPUs already part of current CPU l2-cache mask */
> + cpumask_andnot(mask, mask, cpu_l2_cache_mask(cpu));
> +
> + for_each_cpu(i, mask) {
> /*
> * when updating the marks the current CPU has not been marked
> * online, but we need to update the cache masks
> */
> np = cpu_to_l2cache(i);
> - if (!np)
> - continue;
>
> - if (np == l2_cache)
> - set_cpus_related(cpu, i, cpu_l2_cache_mask);
> + /* Skip all CPUs already part of current CPU l2-cache */
> + if (np == l2_cache) {
> + or_cpumasks_related(cpu, i, submask_fn,
> cpu_l2_cache_mask);
> + cpumask_andnot(mask, mask, submask_fn(i));
> + } else {
> + cpumask_andnot(mask, mask, cpu_l2_cache_mask(i));
> + }
>
> of_node_put(np);
> }
> of_node_put(l2_cache);
> + free_cpumask_var(mask);
>
> return true;
> }
* Qian Cai <[email protected]> [2020-10-07 09:05:42]:
Hi Qian,
Thanks for testing and reporting the failure.
> On Mon, 2020-09-21 at 15:26 +0530, Srikar Dronamraju wrote:
> > All threads of a SMT4 core can either be part of this CPU's l2-cache
> > mask or not related to this CPU l2-cache mask. Use this relation to
> > reduce the number of iterations needed to find all the CPUs that share
> > the same l2-cache.
> >
> > Use a temporary mask to iterate through the CPUs that may share l2_cache
> > mask. Also instead of setting one CPU at a time into cpu_l2_cache_mask,
> > copy the SMT4/sub mask at one shot.
> >
> ...
> > static bool update_mask_by_l2(int cpu)
> > {
> > + struct cpumask *(*submask_fn)(int) = cpu_sibling_mask;
> > struct device_node *l2_cache, *np;
> > + cpumask_var_t mask;
> > int i;
> >
> > l2_cache = cpu_to_l2cache(cpu);
> > @@ -1240,22 +1264,37 @@ static bool update_mask_by_l2(int cpu)
> > return false;
> > }
> >
> > - cpumask_set_cpu(cpu, cpu_l2_cache_mask(cpu));
> > - for_each_cpu_and(i, cpu_online_mask, cpu_cpu_mask(cpu)) {
> > + alloc_cpumask_var_node(&mask, GFP_KERNEL, cpu_to_node(cpu));
>
> Shouldn't this be GFP_ATOMIC? Otherwise, during the CPU hotplugging, we have,
Can you confirm if CONFIG_CPUMASK_OFFSTACK is enabled in your config?
Because if !CONFIG_CPUMASK_OFFSTACK, then alloc_cpumask_var_node would do
nothing but return true.
Regarding CONFIG_CPUMASK_OFFSTACK, not sure how much powerpc was tested
with that config enabled.
Please refer to
http://lore.kernel.org/lkml/[email protected]/t/#u
And we do have an issue to track the same.
https://github.com/linuxppc/issues/issues/321 for enabling/ testing /
verifying if CONFIG_CPUMASK_OFFSTACK works. I also dont see any
powerpc kconfig enabling this.
I do agree with your suggestion that we could substitute
GFP_ATOMIC/GFP_KERNEL.
>
> (irqs were disabled in do_idle())
>
> [ 335.420001][ T0] BUG: sleeping function called from invalid context at mm/slab.h:494
> [ 335.420003][ T0] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 0, name: swapper/88
> [ 335.420005][ T0] no locks held by swapper/88/0.
> [ 335.420007][ T0] irq event stamp: 18074448
> [ 335.420015][ T0] hardirqs last enabled at (18074447): [<c0000000001a2a7c>] tick_nohz_idle_enter+0x9c/0x110
> [ 335.420019][ T0] hardirqs last disabled at (18074448): [<c000000000106798>] do_idle+0x138/0x3b0
> do_idle at kernel/sched/idle.c:253 (discriminator 1)
> [ 335.420023][ T0] softirqs last enabled at (18074440): [<c0000000000bbec4>] irq_enter_rcu+0x94/0xa0
> [ 335.420026][ T0] softirqs last disabled at (18074439): [<c0000000000bbea0>] irq_enter_rcu+0x70/0xa0
> [ 335.420030][ T0] CPU: 88 PID: 0 Comm: swapper/88 Tainted: G W 5.9.0-rc8-next-20201007 #1
> [ 335.420032][ T0] Call Trace:
> [ 335.420037][ T0] [c00020000a4bfcf0] [c000000000649e98] dump_stack+0xec/0x144 (unreliable)
> [ 335.420043][ T0] [c00020000a4bfd30] [c0000000000f6c34] ___might_sleep+0x2f4/0x310
> [ 335.420048][ T0] [c00020000a4bfdb0] [c000000000354f94] slab_pre_alloc_hook.constprop.82+0x124/0x190
> [ 335.420051][ T0] [c00020000a4bfe00] [c00000000035e9e8] __kmalloc_node+0x88/0x3a0
> slab_alloc_node at mm/slub.c:2817
> (inlined by) __kmalloc_node at mm/slub.c:4013
> [ 335.420054][ T0] [c00020000a4bfe80] [c0000000006494d8] alloc_cpumask_var_node+0x38/0x80
> kmalloc_node at include/linux/slab.h:577
> (inlined by) alloc_cpumask_var_node at lib/cpumask.c:116
> [ 335.420060][ T0] [c00020000a4bfef0] [c00000000003eedc] start_secondary+0x27c/0x800
> update_mask_by_l2 at arch/powerpc/kernel/smp.c:1267
> (inlined by) add_cpu_to_masks at arch/powerpc/kernel/smp.c:1387
> (inlined by) start_secondary at arch/powerpc/kernel/smp.c:1420
> [ 335.420063][ T0] [c00020000a4bff90] [c00000000000c468] start_secondary_resume+0x10/0x14
>
> > + cpumask_and(mask, cpu_online_mask, cpu_cpu_mask(cpu));
> > +
> > + if (has_big_cores)
> > + submask_fn = cpu_smallcore_mask;
> > +
> > + /* Update l2-cache mask with all the CPUs that are part of submask */
> > + or_cpumasks_related(cpu, cpu, submask_fn, cpu_l2_cache_mask);
> > +
> > + /* Skip all CPUs already part of current CPU l2-cache mask */
> > + cpumask_andnot(mask, mask, cpu_l2_cache_mask(cpu));
> > +
> > + for_each_cpu(i, mask) {
> > /*
> > * when updating the marks the current CPU has not been marked
> > * online, but we need to update the cache masks
> > */
> > np = cpu_to_l2cache(i);
> > - if (!np)
> > - continue;
> >
> > - if (np == l2_cache)
> > - set_cpus_related(cpu, i, cpu_l2_cache_mask);
> > + /* Skip all CPUs already part of current CPU l2-cache */
> > + if (np == l2_cache) {
> > + or_cpumasks_related(cpu, i, submask_fn,
> > cpu_l2_cache_mask);
> > + cpumask_andnot(mask, mask, submask_fn(i));
> > + } else {
> > + cpumask_andnot(mask, mask, cpu_l2_cache_mask(i));
> > + }
> >
> > of_node_put(np);
> > }
> > of_node_put(l2_cache);
> > + free_cpumask_var(mask);
> >
> > return true;
> > }
>
--
Thanks and Regards
Srikar Dronamraju
On Wed, 2020-10-07 at 19:47 +0530, Srikar Dronamraju wrote:
> Can you confirm if CONFIG_CPUMASK_OFFSTACK is enabled in your config?
Yes, https://gitlab.com/cailca/linux-mm/-/blob/master/powerpc.config
We tested here almost daily on linux-next.