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.
Aslo we don't have such check in brother function
clear_global_latency_tracing.
Notes: These changes only visible to users who sets CONFIG_LATENCYTOP and
won't change user tool latencytop's behaviors.
Signed-off-by: Lin Feng <l...@wangsu.com>
---
kernel/latencytop.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/kernel/latencytop.c b/kernel/latencytop.c
index 9e794b49791e..897895efafd9 100644
--- a/kernel/latencytop.c
+++ b/kernel/latencytop.c
@@ -71,9 +71,6 @@ void clear_tsk_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;
--
2.20.1
