* [PATCH v4 0/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level
@ 2024-04-30 15:05 Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 1/3] " Vitalii Bursov
` (2 more replies)
0 siblings, 3 replies; 9+ messages in thread
From: Vitalii Bursov @ 2024-04-30 15:05 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Daniel Bristot de Oliveira, Valentin Schneider, linux-kernel,
Vitalii Bursov, Shrikanth Hegde
Changes in v4:
- Updated commit messages: set Fixes tag to a proper commit,
comment about SDM macro in a debug commit.
- Link to v3: https://lore.kernel.org/lkml/cover.1712147341.git.vitaly@bursov.com/
Changes in v3:
- Remove levels table change from the documentation patch
- Link to v2: https://lore.kernel.org/lkml/cover.1711900396.git.vitaly@bursov.com/
Changes in v2:
- Split debug.c change in a separate commit and move new "level"
after "groups_flags"
- Added "Fixes" tag and updated commit message
- Update domain levels cgroup-v1/cpusets.rst documentation
- Link to v1: https://lore.kernel.org/all/cover.1711584739.git.vitaly@bursov.com/
During the upgrade from Linux 5.4 we found a small (around 3%)
performance regression which was tracked to commit
c5b0a7eefc70150caf23e37bc9d639c68c87a097
sched/fair: Remove sysctl_sched_migration_cost condition
With a default value of 500us, sysctl_sched_migration_cost is
significanlty higher than the cost of load_balance. Remove the
condition and rely on the sd->max_newidle_lb_cost to abort
newidle_balance.
Looks like "newidle" balancing is beneficial for a lot of workloads,
just not for this specific one. The workload is video encoding, there
are 100s-1000s of threads, some are synchronized with mutexes and
conditional variables. The process aims to have a portion of CPU idle,
so no CPU cores are 100% busy. Perhaps, the performance impact we see
comes from additional processing in the scheduler and additional cost
like more cache misses, and not from an incorrect balancing. See
perf output below.
My understanding is that "sched_relax_domain_level" cgroup parameter
should control if sched_balance_newidle() is called and what's the scope
of the balancing is, but it doesn't fully work for this case.
cpusets.rst documentation:
> The 'cpuset.sched_relax_domain_level' file allows you to request changing
> this searching range as you like. This file takes int value which
> indicates size of searching range in levels ideally as follows,
> otherwise initial value -1 that indicates the cpuset has no request.
>
> ====== ===========================================================
> -1 no request. use system default or follow request of others.
> 0 no search.
> 1 search siblings (hyperthreads in a core).
> 2 search cores in a package.
> 3 search cpus in a node [= system wide on non-NUMA system]
> 4 search nodes in a chunk of node [on NUMA system]
> 5 search system wide [on NUMA system]
> ====== ===========================================================
Setting cpuset.sched_relax_domain_level to 0 works as 1.
On a dual-CPU server, domains and levels are as follows:
domain 0: level 0, SMT
domain 1: level 2, MC
domain 2: level 5, NUMA
So, to support "0 no search", the value in
cpuset.sched_relax_domain_level should disable SD_BALANCE_NEWIDLE for a
specified level and keep it enabled for prior levels. For example, SMT
level is 0, so sched_relax_domain_level=0 should exclude levels >=0.
Instead, cpuset.sched_relax_domain_level enables the specified level,
which effectively removes "no search" option. See below for domain
flags for all cpuset.sched_relax_domain_level values.
Proposed patch allows clearing SD_BALANCE_NEWIDLE flags when
cpuset.sched_relax_domain_level is set to 0 and extends max
value validation range beyond sched_domain_level_max. This allows
setting SD_BALANCE_NEWIDLE on all levels and override platform
default if it does not include all levels.
Thanks
=========================
Perf output for a simimar workload/test case shows that newidle_balance
(now renamed to sched_balance_newidle) is called when handling futex and
nanosleep syscalls:
8.74% 0.40% a.out [kernel.vmlinux] [k] entry_SYSCALL_64
8.34% entry_SYSCALL_64
- do_syscall_64
- 5.50% __x64_sys_futex
- 5.42% do_futex
- 3.79% futex_wait
- 3.74% __futex_wait
- 3.53% futex_wait_queue
- 3.45% schedule
- 3.43% __schedule
- 2.06% pick_next_task
- 1.93% pick_next_task_fair
- 1.87% newidle_balance
- 1.52% load_balance
- 1.16% find_busiest_group
- 1.13% update_sd_lb_stats.constprop.0
1.01% update_sg_lb_stats
- 0.83% dequeue_task_fair
0.66% dequeue_entity
- 1.57% futex_wake
- 1.22% wake_up_q
- 1.20% try_to_wake_up
0.58% select_task_rq_fair
- 2.44% __x64_sys_nanosleep
- 2.36% hrtimer_nanosleep
- 2.33% do_nanosleep
- 2.05% schedule
- 2.03% __schedule
- 1.23% pick_next_task
- 1.15% pick_next_task_fair
- 1.12% newidle_balance
- 0.90% load_balance
- 0.68% find_busiest_group
- 0.66% update_sd_lb_stats.constprop.0
0.59% update_sg_lb_stats
0.52% dequeue_task_fair
When newidle_balance is disabled (or when using older kernels), perf
output is:
6.37% 0.41% a.out [kernel.vmlinux] [k] entry_SYSCALL_64
5.96% entry_SYSCALL_64
- do_syscall_64
- 3.97% __x64_sys_futex
- 3.89% do_futex
- 2.32% futex_wait
- 2.27% __futex_wait
- 2.05% futex_wait_queue
- 1.98% schedule
- 1.96% __schedule
- 0.81% dequeue_task_fair
0.66% dequeue_entity
- 0.64% pick_next_task
0.51% pick_next_task_fair
- 1.52% futex_wake
- 1.15% wake_up_q
- try_to_wake_up
0.59% select_task_rq_fair
- 1.58% __x64_sys_nanosleep
- 1.52% hrtimer_nanosleep
- 1.48% do_nanosleep
- 1.20% schedule
- 1.19% __schedule
0.53% dequeue_task_fair
Without a patch:
=========================
CPUs: 2 Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz
# uname -r
6.8.1
# numactl -H
available: 2 nodes (0-1)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 24 25 26 27 28 29 30 31 32 33 34 35
node 0 size: 63962 MB
node 0 free: 59961 MB
node 1 cpus: 12 13 14 15 16 17 18 19 20 21 22 23 36 37 38 39 40 41 42 43 44 45 46 47
node 1 size: 64446 MB
node 1 free: 63338 MB
node distances:
node 0 1
0: 10 21
1: 21 10
# head /proc/schedstat
version 15
timestamp 4295347219
cpu0 0 0 0 0 0 0 3035466036 858375615 67578
domain0 0000,01000001 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0...
domain1 000f,ff000fff 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0...
domain2 ffff,ffffffff 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0...
# cd /sys/kernel/debug/sched/domains
# echo -1 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{name,flags,groups_flags,max_newidle_lb_cost}
cpu0/domain0/name:SMT
cpu0/domain1/name:MC
cpu0/domain2/name:NUMA
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_CPUCAPACITY
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SERIALIZE SD_OVERLAP
SD_NUMA
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_CPUCAPACITY SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain0/max_newidle_lb_cost:2236
cpu0/domain1/max_newidle_lb_cost:3444
cpu0/domain2/max_newidle_lb_cost:4590
# echo 0 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags,max_newidle_lb_cost}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_CPUCAPACITY
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain1/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain2/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SERIALIZE SD_OVERLAP SD_NUMA
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_CPUCAPACITY SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/groups_flags:SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain0/max_newidle_lb_cost:0
cpu0/domain1/max_newidle_lb_cost:0
cpu0/domain2/max_newidle_lb_cost:0
# echo 1 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags,max_newidle_lb_cost}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_CPUCAPACITY
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain1/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain2/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SERIALIZE SD_OVERLAP SD_NUMA
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_CPUCAPACITY SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/groups_flags:SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain0/max_newidle_lb_cost:309
cpu0/domain1/max_newidle_lb_cost:0
cpu0/domain2/max_newidle_lb_cost:0
# echo 2 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags,max_newidle_lb_cost}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_CPUCAPACITY
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SERIALIZE SD_OVERLAP SD_NUMA
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_CPUCAPACITY SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain0/max_newidle_lb_cost:276
cpu0/domain1/max_newidle_lb_cost:2776
cpu0/domain2/max_newidle_lb_cost:0
# echo 3 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags,max_newidle_lb_cost}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_CPUCAPACITY
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SERIALIZE SD_OVERLAP SD_NUMA
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_CPUCAPACITY SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain0/max_newidle_lb_cost:289
cpu0/domain1/max_newidle_lb_cost:3192
cpu0/domain2/max_newidle_lb_cost:0
# echo 4 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags,max_newidle_lb_cost}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_CPUCAPACITY
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC SD_BALANCE_FORK
SD_WAKE_AFFINE SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/flags:SD_BALANCE_EXEC SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SERIALIZE SD_OVERLAP SD_NUMA
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_CPUCAPACITY SD_SHARE_PKG_RESOURCES
SD_PREFER_SIBLING
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC
SD_BALANCE_FORK SD_WAKE_AFFINE
SD_SHARE_PKG_RESOURCES SD_PREFER_SIBLING
cpu0/domain0/max_newidle_lb_cost:1306
cpu0/domain1/max_newidle_lb_cost:1999
cpu0/domain2/max_newidle_lb_cost:0
# echo 5 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
bash: echo: write error: Invalid argument
=========================
The same system with the patch applied:
=========================
# cd /sys/kernel/debug/sched/domains
# echo -1 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{name,level,flags,groups_flags}
cpu0/domain0/name:SMT
cpu0/domain1/name:MC
cpu0/domain2/name:NUMA
cpu0/domain0/level:0
cpu0/domain1/level:2
cpu0/domain2/level:5
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
# echo 0 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags}
cpu0/domain0/flags:SD_BALANCE_EXEC ...
cpu0/domain1/flags:SD_BALANCE_EXEC ...
cpu0/domain2/flags:SD_BALANCE_EXEC ...
cpu0/domain1/groups_flags:SD_BALANCE_EXEC ...
cpu0/domain2/groups_flags:SD_BALANCE_EXEC ...
# echo 1 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain1/flags:SD_BALANCE_EXEC ...
cpu0/domain2/flags:SD_BALANCE_EXEC ...
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/groups_flags:SD_BALANCE_EXEC ...
[skip 2, same as 1]
# echo 3 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/flags:SD_BALANCE_EXEC ...
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
[skip 4 and 5, same as 3]
# echo 6 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
# grep . cpu0/*/{flags,groups_flags}
cpu0/domain0/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain1/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain1/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
cpu0/domain2/groups_flags:SD_BALANCE_NEWIDLE SD_BALANCE_EXEC ...
# echo 7 > /sys/fs/cgroup/cpuset/cpuset.sched_relax_domain_level
bash: echo: write error: Invalid argument
=========================
Vitalii Bursov (3):
sched/fair: allow disabling sched_balance_newidle with
sched_relax_domain_level
sched/debug: dump domains' level
docs: cgroup-v1: clarify that domain levels are system-specific
Documentation/admin-guide/cgroup-v1/cpusets.rst | 7 ++++++-
kernel/cgroup/cpuset.c | 2 +-
kernel/sched/debug.c | 1 +
kernel/sched/topology.c | 2 +-
4 files changed, 9 insertions(+), 3 deletions(-)
--
2.20.1
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH v4 1/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level
2024-04-30 15:05 [PATCH v4 0/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level Vitalii Bursov
@ 2024-04-30 15:05 ` Vitalii Bursov
2024-05-02 16:01 ` Valentin Schneider
2024-05-17 8:06 ` [tip: sched/urgent] sched/fair: Allow " tip-bot2 for Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 2/3] sched/debug: dump domains' level Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 3/3] docs: cgroup-v1: clarify that domain levels are system-specific Vitalii Bursov
2 siblings, 2 replies; 9+ messages in thread
From: Vitalii Bursov @ 2024-04-30 15:05 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Daniel Bristot de Oliveira, Valentin Schneider, linux-kernel,
Vitalii Bursov, Shrikanth Hegde
Change relax_domain_level checks so that it would be possible
to include or exclude all domains from newidle balancing.
This matches the behavior described in the documentation:
-1 no request. use system default or follow request of others.
0 no search.
1 search siblings (hyperthreads in a core).
"2" enables levels 0 and 1, level_max excludes the last (level_max)
level, and level_max+1 includes all levels.
Fixes: 1d3504fcf560 ("sched, cpuset: customize sched domains, core")
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
kernel/cgroup/cpuset.c | 2 +-
kernel/sched/topology.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4237c8748715..da24187c4e02 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2948,7 +2948,7 @@ bool current_cpuset_is_being_rebound(void)
static int update_relax_domain_level(struct cpuset *cs, s64 val)
{
#ifdef CONFIG_SMP
- if (val < -1 || val >= sched_domain_level_max)
+ if (val < -1 || val > sched_domain_level_max + 1)
return -EINVAL;
#endif
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 63aecd2a7a9f..67a777b31743 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1475,7 +1475,7 @@ static void set_domain_attribute(struct sched_domain *sd,
} else
request = attr->relax_domain_level;
- if (sd->level > request) {
+ if (sd->level >= request) {
/* Turn off idle balance on this domain: */
sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
}
--
2.20.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v4 2/3] sched/debug: dump domains' level
2024-04-30 15:05 [PATCH v4 0/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 1/3] " Vitalii Bursov
@ 2024-04-30 15:05 ` Vitalii Bursov
2024-05-02 16:01 ` Valentin Schneider
2024-05-17 8:06 ` [tip: sched/urgent] sched/debug: Dump " tip-bot2 for Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 3/3] docs: cgroup-v1: clarify that domain levels are system-specific Vitalii Bursov
2 siblings, 2 replies; 9+ messages in thread
From: Vitalii Bursov @ 2024-04-30 15:05 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Daniel Bristot de Oliveira, Valentin Schneider, linux-kernel,
Vitalii Bursov, Shrikanth Hegde
Knowing domain's level exactly can be useful when setting
relax_domain_level or cpuset.sched_relax_domain_level
Usage:
cat /debug/sched/domains/cpu0/domain1/level
to dump cpu0 domain1's level.
SDM macro is not used because sd->level is int and
it would hide the type mismatch between int and u32.
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
---
kernel/sched/debug.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 8d5d98a5834d..c1eb9a1afd13 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -425,6 +425,7 @@ static void register_sd(struct sched_domain *sd, struct dentry *parent)
debugfs_create_file("flags", 0444, parent, &sd->flags, &sd_flags_fops);
debugfs_create_file("groups_flags", 0444, parent, &sd->groups->flags, &sd_flags_fops);
+ debugfs_create_u32("level", 0444, parent, (u32 *)&sd->level);
}
void update_sched_domain_debugfs(void)
--
2.20.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [PATCH v4 3/3] docs: cgroup-v1: clarify that domain levels are system-specific
2024-04-30 15:05 [PATCH v4 0/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 1/3] " Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 2/3] sched/debug: dump domains' level Vitalii Bursov
@ 2024-04-30 15:05 ` Vitalii Bursov
2024-05-17 8:06 ` [tip: sched/urgent] docs: cgroup-v1: Clarify " tip-bot2 for Vitalii Bursov
2 siblings, 1 reply; 9+ messages in thread
From: Vitalii Bursov @ 2024-04-30 15:05 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot,
Dietmar Eggemann, Steven Rostedt, Ben Segall, Mel Gorman,
Daniel Bristot de Oliveira, Valentin Schneider, linux-kernel,
Vitalii Bursov, Shrikanth Hegde
Add a clarification that domain levels are system-specific
and where to check for system details.
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
---
Documentation/admin-guide/cgroup-v1/cpusets.rst | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/cgroup-v1/cpusets.rst b/Documentation/admin-guide/cgroup-v1/cpusets.rst
index 7d3415eea05d..f401af5e2f09 100644
--- a/Documentation/admin-guide/cgroup-v1/cpusets.rst
+++ b/Documentation/admin-guide/cgroup-v1/cpusets.rst
@@ -568,7 +568,7 @@ on the next tick. For some applications in special situation, waiting
The 'cpuset.sched_relax_domain_level' file allows you to request changing
this searching range as you like. This file takes int value which
-indicates size of searching range in levels ideally as follows,
+indicates size of searching range in levels approximately as follows,
otherwise initial value -1 that indicates the cpuset has no request.
====== ===========================================================
@@ -581,6 +581,11 @@ otherwise initial value -1 that indicates the cpuset has no request.
5 search system wide [on NUMA system]
====== ===========================================================
+Not all levels can be present and values can change depending on the
+system architecture and kernel configuration. Check
+/sys/kernel/debug/sched/domains/cpu*/domain*/ for system-specific
+details.
+
The system default is architecture dependent. The system default
can be changed using the relax_domain_level= boot parameter.
--
2.20.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH v4 2/3] sched/debug: dump domains' level
2024-04-30 15:05 ` [PATCH v4 2/3] sched/debug: dump domains' level Vitalii Bursov
@ 2024-05-02 16:01 ` Valentin Schneider
2024-05-17 8:06 ` [tip: sched/urgent] sched/debug: Dump " tip-bot2 for Vitalii Bursov
1 sibling, 0 replies; 9+ messages in thread
From: Valentin Schneider @ 2024-05-02 16:01 UTC (permalink / raw)
To: Vitalii Bursov, Ingo Molnar, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Daniel Bristot de Oliveira, linux-kernel,
Vitalii Bursov, Shrikanth Hegde
On 30/04/24 18:05, Vitalii Bursov wrote:
> Knowing domain's level exactly can be useful when setting
> relax_domain_level or cpuset.sched_relax_domain_level
>
> Usage:
> cat /debug/sched/domains/cpu0/domain1/level
> to dump cpu0 domain1's level.
>
> SDM macro is not used because sd->level is int and
> it would hide the type mismatch between int and u32.
>
> Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
> Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
> Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4 1/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level
2024-04-30 15:05 ` [PATCH v4 1/3] " Vitalii Bursov
@ 2024-05-02 16:01 ` Valentin Schneider
2024-05-17 8:06 ` [tip: sched/urgent] sched/fair: Allow " tip-bot2 for Vitalii Bursov
1 sibling, 0 replies; 9+ messages in thread
From: Valentin Schneider @ 2024-05-02 16:01 UTC (permalink / raw)
To: Vitalii Bursov, Ingo Molnar, Peter Zijlstra, Juri Lelli,
Vincent Guittot, Dietmar Eggemann, Steven Rostedt, Ben Segall,
Mel Gorman, Daniel Bristot de Oliveira, linux-kernel,
Vitalii Bursov, Shrikanth Hegde
On 30/04/24 18:05, Vitalii Bursov wrote:
> Change relax_domain_level checks so that it would be possible
> to include or exclude all domains from newidle balancing.
>
> This matches the behavior described in the documentation:
> -1 no request. use system default or follow request of others.
> 0 no search.
> 1 search siblings (hyperthreads in a core).
>
> "2" enables levels 0 and 1, level_max excludes the last (level_max)
> level, and level_max+1 includes all levels.
>
> Fixes: 1d3504fcf560 ("sched, cpuset: customize sched domains, core")
> Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
^ permalink raw reply [flat|nested] 9+ messages in thread
* [tip: sched/urgent] docs: cgroup-v1: Clarify that domain levels are system-specific
2024-04-30 15:05 ` [PATCH v4 3/3] docs: cgroup-v1: clarify that domain levels are system-specific Vitalii Bursov
@ 2024-05-17 8:06 ` tip-bot2 for Vitalii Bursov
0 siblings, 0 replies; 9+ messages in thread
From: tip-bot2 for Vitalii Bursov @ 2024-05-17 8:06 UTC (permalink / raw)
To: linux-tip-commits
Cc: Vitalii Bursov, Ingo Molnar, Valentin Schneider, Vincent Guittot,
x86, linux-kernel
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 0f1c74befa656305ecc85c954dc31f84c1cc26e1
Gitweb: https://git.kernel.org/tip/0f1c74befa656305ecc85c954dc31f84c1cc26e1
Author: Vitalii Bursov <vitaly@bursov.com>
AuthorDate: Tue, 30 Apr 2024 18:05:25 +03:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 17 May 2024 09:48:25 +02:00
docs: cgroup-v1: Clarify that domain levels are system-specific
Add a clarification that domain levels are system-specific
and where to check for system details.
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/42b177a2e897cdf880caf9c2025f5b609e820334.1714488502.git.vitaly@bursov.com
---
Documentation/admin-guide/cgroup-v1/cpusets.rst | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/cgroup-v1/cpusets.rst b/Documentation/admin-guide/cgroup-v1/cpusets.rst
index 7d3415e..f401af5 100644
--- a/Documentation/admin-guide/cgroup-v1/cpusets.rst
+++ b/Documentation/admin-guide/cgroup-v1/cpusets.rst
@@ -568,7 +568,7 @@ on the next tick. For some applications in special situation, waiting
The 'cpuset.sched_relax_domain_level' file allows you to request changing
this searching range as you like. This file takes int value which
-indicates size of searching range in levels ideally as follows,
+indicates size of searching range in levels approximately as follows,
otherwise initial value -1 that indicates the cpuset has no request.
====== ===========================================================
@@ -581,6 +581,11 @@ otherwise initial value -1 that indicates the cpuset has no request.
5 search system wide [on NUMA system]
====== ===========================================================
+Not all levels can be present and values can change depending on the
+system architecture and kernel configuration. Check
+/sys/kernel/debug/sched/domains/cpu*/domain*/ for system-specific
+details.
+
The system default is architecture dependent. The system default
can be changed using the relax_domain_level= boot parameter.
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [tip: sched/urgent] sched/debug: Dump domains' level
2024-04-30 15:05 ` [PATCH v4 2/3] sched/debug: dump domains' level Vitalii Bursov
2024-05-02 16:01 ` Valentin Schneider
@ 2024-05-17 8:06 ` tip-bot2 for Vitalii Bursov
1 sibling, 0 replies; 9+ messages in thread
From: tip-bot2 for Vitalii Bursov @ 2024-05-17 8:06 UTC (permalink / raw)
To: linux-tip-commits
Cc: Vitalii Bursov, Ingo Molnar, Dietmar Eggemann, Vincent Guittot,
Valentin Schneider, x86, linux-kernel
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 287372fa39f579a61e17b000aa74c8418d230528
Gitweb: https://git.kernel.org/tip/287372fa39f579a61e17b000aa74c8418d230528
Author: Vitalii Bursov <vitaly@bursov.com>
AuthorDate: Tue, 30 Apr 2024 18:05:24 +03:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 17 May 2024 09:48:25 +02:00
sched/debug: Dump domains' level
Knowing domain's level exactly can be useful when setting
relax_domain_level or cpuset.sched_relax_domain_level
Usage:
cat /debug/sched/domains/cpu0/domain1/level
to dump cpu0 domain1's level.
SDM macro is not used because sd->level is 'int' and
it would hide the type mismatch between 'int' and 'u32'.
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/9489b6475f6dd6fbc67c617752d4216fa094da53.1714488502.git.vitaly@bursov.com
---
kernel/sched/debug.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 8d5d98a..c1eb9a1 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -425,6 +425,7 @@ static void register_sd(struct sched_domain *sd, struct dentry *parent)
debugfs_create_file("flags", 0444, parent, &sd->flags, &sd_flags_fops);
debugfs_create_file("groups_flags", 0444, parent, &sd->groups->flags, &sd_flags_fops);
+ debugfs_create_u32("level", 0444, parent, (u32 *)&sd->level);
}
void update_sched_domain_debugfs(void)
^ permalink raw reply related [flat|nested] 9+ messages in thread
* [tip: sched/urgent] sched/fair: Allow disabling sched_balance_newidle with sched_relax_domain_level
2024-04-30 15:05 ` [PATCH v4 1/3] " Vitalii Bursov
2024-05-02 16:01 ` Valentin Schneider
@ 2024-05-17 8:06 ` tip-bot2 for Vitalii Bursov
1 sibling, 0 replies; 9+ messages in thread
From: tip-bot2 for Vitalii Bursov @ 2024-05-17 8:06 UTC (permalink / raw)
To: linux-tip-commits
Cc: Vitalii Bursov, Ingo Molnar, Dietmar Eggemann, Vincent Guittot,
Valentin Schneider, x86, linux-kernel
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: a1fd0b9d751f840df23ef0e75b691fc00cfd4743
Gitweb: https://git.kernel.org/tip/a1fd0b9d751f840df23ef0e75b691fc00cfd4743
Author: Vitalii Bursov <vitaly@bursov.com>
AuthorDate: Tue, 30 Apr 2024 18:05:23 +03:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Fri, 17 May 2024 09:48:24 +02:00
sched/fair: Allow disabling sched_balance_newidle with sched_relax_domain_level
Change relax_domain_level checks so that it would be possible
to include or exclude all domains from newidle balancing.
This matches the behavior described in the documentation:
-1 no request. use system default or follow request of others.
0 no search.
1 search siblings (hyperthreads in a core).
"2" enables levels 0 and 1, level_max excludes the last (level_max)
level, and level_max+1 includes all levels.
Fixes: 1d3504fcf560 ("sched, cpuset: customize sched domains, core")
Signed-off-by: Vitalii Bursov <vitaly@bursov.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/bd6de28e80073c79466ec6401cdeae78f0d4423d.1714488502.git.vitaly@bursov.com
---
kernel/cgroup/cpuset.c | 2 +-
kernel/sched/topology.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4237c87..da24187 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2948,7 +2948,7 @@ bool current_cpuset_is_being_rebound(void)
static int update_relax_domain_level(struct cpuset *cs, s64 val)
{
#ifdef CONFIG_SMP
- if (val < -1 || val >= sched_domain_level_max)
+ if (val < -1 || val > sched_domain_level_max + 1)
return -EINVAL;
#endif
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 63aecd2..67a777b 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -1475,7 +1475,7 @@ static void set_domain_attribute(struct sched_domain *sd,
} else
request = attr->relax_domain_level;
- if (sd->level > request) {
+ if (sd->level >= request) {
/* Turn off idle balance on this domain: */
sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE);
}
^ permalink raw reply related [flat|nested] 9+ messages in thread
end of thread, other threads:[~2024-05-17 8:06 UTC | newest]
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2024-04-30 15:05 [PATCH v4 0/3] sched/fair: allow disabling sched_balance_newidle with sched_relax_domain_level Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 1/3] " Vitalii Bursov
2024-05-02 16:01 ` Valentin Schneider
2024-05-17 8:06 ` [tip: sched/urgent] sched/fair: Allow " tip-bot2 for Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 2/3] sched/debug: dump domains' level Vitalii Bursov
2024-05-02 16:01 ` Valentin Schneider
2024-05-17 8:06 ` [tip: sched/urgent] sched/debug: Dump " tip-bot2 for Vitalii Bursov
2024-04-30 15:05 ` [PATCH v4 3/3] docs: cgroup-v1: clarify that domain levels are system-specific Vitalii Bursov
2024-05-17 8:06 ` [tip: sched/urgent] docs: cgroup-v1: Clarify " tip-bot2 for Vitalii Bursov
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