diff options
| author | Shrikanth Hegde <sshegde@linux.ibm.com> | 2026-03-24 01:06:28 +0530 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-03-24 10:07:05 +0100 |
| commit | 0e81fe79fec5a639700f09f39c8ab680c3312ba2 (patch) | |
| tree | 1be7371ae11da8fe6023f122529b672590971754 /kernel | |
| parent | 76504bce4ee6b8757647e07bc1710dcac9acdc2e (diff) | |
sched/core: Get this cpu once in ttwu_queue_cond()
Calling smp_processor_id() on:
- In CONFIG_DEBUG_PREEMPT=y, if preemption/irq is disabled, then it does
not print any warning.
- In CONFIG_DEBUG_PREEMPT=n, it doesn't do anything apart from getting
__smp_processor_id
So with both CONFIG_DEBUG_PREEMPT=y/n, in preemption disabled section
it is better to cache the value. It could save a few cycles. Though
tiny, repeated could add up to a small value.
ttwu_queue_cond is called with interrupt disabled. So preemption is
disabled. Hence cache the value once instead.
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Link: https://patch.msgid.link/20260323193630.640311-3-sshegde@linux.ibm.com
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/core.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 64b467c1d5b6..7c7d4bf686d7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3842,6 +3842,8 @@ bool cpus_share_resources(int this_cpu, int that_cpu) static inline bool ttwu_queue_cond(struct task_struct *p, int cpu) { + int this_cpu = smp_processor_id(); + /* See SCX_OPS_ALLOW_QUEUED_WAKEUP. */ if (!scx_allow_ttwu_queue(p)) return false; @@ -3866,10 +3868,10 @@ static inline bool ttwu_queue_cond(struct task_struct *p, int cpu) * If the CPU does not share cache, then queue the task on the * remote rqs wakelist to avoid accessing remote data. */ - if (!cpus_share_cache(smp_processor_id(), cpu)) + if (!cpus_share_cache(this_cpu, cpu)) return true; - if (cpu == smp_processor_id()) + if (cpu == this_cpu) return false; /* |