Valentin Schneider 6f693dd5be 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		2020-03-06 12:57:23 +01:00
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defconfig	arm64: defconfig: enable CONFIG_SCHED_SMT	2020-03-06 12:57:23 +01:00