diff options
| author | Valentin Schneider <valentin.schneider@arm.com> | 2020-02-27 19:14:33 +0000 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-03-06 12:57:23 +0100 |
| commit | 6f693dd5be08237b337f557c510d99addb9eb9ec (patch) | |
| tree | 6d78504d305ee92e75c35d05ebd0d95c26b88e00 /arch/arm64/configs | |
| parent | 38502ab4bf3c463081bfd53356980a9ec2f32d1d (diff) | |
arm64: defconfig: enable CONFIG_SCHED_SMT
The (CFS) scheduler has some extra logic catering to systems with SMT, but
that logic won't be compiled in unless the above config is set.
Note that the SMT-centric codepaths are gated by the sched_smt_present
static key, and the SMT sched_domains will only survive if the platform has
SMT. As such, the only impact on !SMT platforms should be a slightly
bigger kernel - no behavioural change.
Distro kernels already enable it, which makes sense since there already are
things like ThunderX2 out in the wild. Enable it for the defconfig.
Some deltas
===========
FWIW my ELF symbol table diff looks something like this:
NAME BEFORE AFTER DELTA
update_sd_lb_stats.constprop.135 0 1864 +1864
find_idlest_group.isra.115 0 1808 +1808
update_numa_stats.isra.121 0 628 +628
select_task_rq_fair 3236 3732 +496
compute_energy.isra.112 0 420 +420
score_nearby_nodes.part.120 0 380 +380
__update_idle_core 0 232 +232
nohz_balance_exit_idle.part.127 0 216 +216
sched_slice.isra.99 0 172 +172
update_load_avg.part.107 0 116 +116
wakeup_preempt_entity.isra.101 0 92 +92
sched_cpu_activate 340 396 +56
pick_next_task_idle 8 56 +48
sched_cpu_deactivate 252 292 +40
show_smt_active 44 80 +36
cpu_smt_mask 0 28 +28
set_next_task_idle 4 32 +28
task_numa_work 680 692 +12
cpu_smt_flags 0 8 +8
enqueue_task_fair 2608 2612 +4
wakeup_preempt_entity.isra.104 92 0 -92
update_load_avg 1028 932 -96
task_numa_migrate 1824 1728 -96
sched_slice.isra.102 172 0 -172
nohz_balance_exit_idle.part.130 216 0 -216
task_numa_find_cpu 2116 1868 -248
score_nearby_nodes.part.123 380 0 -380
compute_energy.isra.115 420 0 -420
update_numa_stats.isra.124 472 0 -472
find_idlest_group.isra.118 1808 0 -1808
update_sd_lb_stats.constprop.138 1864 0 -1864
------------------------------------------------------------------
DELTA SUM +820
As for the sched_domains, this is on a hikey960:
before:
$ cat /proc/sys/kernel/sched_domain/cpu*/domain*/name | sort | uniq
DIE
MC
after:
$ cat /proc/sys/kernel/sched_domain/cpu*/domain*/name | sort | uniq
DIE
MC
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20200227191433.31994-3-valentin.schneider@arm.com
Diffstat (limited to 'arch/arm64/configs')
| -rw-r--r-- | arch/arm64/configs/defconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig index 905109f6814f..3e75007f6592 100644 --- a/arch/arm64/configs/defconfig +++ b/arch/arm64/configs/defconfig @@ -62,6 +62,7 @@ CONFIG_ARCH_ZX=y CONFIG_ARCH_ZYNQMP=y CONFIG_ARM64_VA_BITS_48=y CONFIG_SCHED_MC=y +CONFIG_SCHED_SMT=y CONFIG_NUMA=y CONFIG_SECCOMP=y CONFIG_KEXEC=y |