From: Lin Feng Date: Tue, 14 May 2019 22:42:31 +0000 (-0700) Subject: kernel/latencytop.c: remove unnecessary checks for latencytop_enabled X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=0cc75888dad112395df0ac755915ceb79811831c;p=openwrt%2Fstaging%2Fblogic.git kernel/latencytop.c: remove unnecessary checks for latencytop_enabled 1. In latencytop source codes, we only have such calling chain: account_scheduler_latency(struct task_struct *task, int usecs, int inter) { if (unlikely(latencytop_enabled)) /* the outtermost check */ __account_scheduler_latency(task, usecs, inter); } __account_scheduler_latency account_global_scheduler_latency if (!latencytop_enabled) So, the inner check for latencytop_enabled is not necessary at all. 2. In clear_all_latency_tracing and now is called clear_tsk_latency_tracing the check for latencytop_enabled is redundant and buggy to some extent. We have no reason to refuse clearing the /proc/$pid/latency if latencytop_enabled is set to 0, considering that if we use latencytop manually by echo 0 > /proc/sys/kernel/latencytop, then we want to clear /proc/$pid/latency and failed. Also we don't have such check in brother function clear_global_latency_tracing. Notes: These changes are only visible to users who set CONFIG_LATENCYTOP and won't change user tool latencytop's behavior. Link: http://lkml.kernel.org/r/20190226114602.16902-2-linf@wangsu.com Signed-off-by: Lin Feng Cc: Alexey Dobriyan Cc: Fabian Frederick Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/latencytop.c b/kernel/latencytop.c index 99a5b5f46dc5..bbde5614da71 100644 --- a/kernel/latencytop.c +++ b/kernel/latencytop.c @@ -71,9 +71,6 @@ void clear_all_latency_tracing(struct task_struct *p) { unsigned long flags; - if (!latencytop_enabled) - return; - raw_spin_lock_irqsave(&latency_lock, flags); memset(&p->latency_record, 0, sizeof(p->latency_record)); p->latency_record_count = 0; @@ -96,9 +93,6 @@ account_global_scheduler_latency(struct task_struct *tsk, int firstnonnull = MAXLR + 1; int i; - if (!latencytop_enabled) - return; - /* skip kernel threads for now */ if (!tsk->mm) return;