* [PATCH] mm: Place "not" inside of unlikely() statement in wb_domain_writeout_inc()
@ 2017-02-06 17:00 Steven Rostedt
2017-02-07 11:04 ` Jan Kara
0 siblings, 1 reply; 2+ messages in thread
From: Steven Rostedt @ 2017-02-06 17:00 UTC (permalink / raw)
To: LKML; +Cc: Andrew Morton, Jan Kara
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
The likely/unlikely profiler noticed that the unlikely statement in
wb_domain_writeout_inc() is constantly wrong. This is due to the "not" (!)
being outside the unlikely statement. It is likely that dom->period_time
will be set, but unlikely that it wont be. Move the not into the unlikely
statement.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
mm/page-writeback.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 290e8b7..94102c7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -580,7 +580,7 @@ static void wb_domain_writeout_inc(struct wb_domain *dom,
__fprop_inc_percpu_max(&dom->completions, completions,
max_prop_frac);
/* First event after period switching was turned off? */
- if (!unlikely(dom->period_time)) {
+ if (unlikely(!dom->period_time)) {
/*
* We can race with other __bdi_writeout_inc calls here but
* it does not cause any harm since the resulting time when
--
2.9.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] mm: Place "not" inside of unlikely() statement in wb_domain_writeout_inc()
2017-02-06 17:00 [PATCH] mm: Place "not" inside of unlikely() statement in wb_domain_writeout_inc() Steven Rostedt
@ 2017-02-07 11:04 ` Jan Kara
0 siblings, 0 replies; 2+ messages in thread
From: Jan Kara @ 2017-02-07 11:04 UTC (permalink / raw)
To: Steven Rostedt; +Cc: LKML, Andrew Morton, Jan Kara
On Mon 06-02-17 12:00:35, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> The likely/unlikely profiler noticed that the unlikely statement in
> wb_domain_writeout_inc() is constantly wrong. This is due to the "not" (!)
> being outside the unlikely statement. It is likely that dom->period_time
> will be set, but unlikely that it wont be. Move the not into the unlikely
> statement.
>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Yeah, good catch. You can add:
Reviewed-by: Jan Kara <jack@suse.cz>
Andrew, will you merge this patch please? Thanks!
Honza
> ---
> mm/page-writeback.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 290e8b7..94102c7 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -580,7 +580,7 @@ static void wb_domain_writeout_inc(struct wb_domain *dom,
> __fprop_inc_percpu_max(&dom->completions, completions,
> max_prop_frac);
> /* First event after period switching was turned off? */
> - if (!unlikely(dom->period_time)) {
> + if (unlikely(!dom->period_time)) {
> /*
> * We can race with other __bdi_writeout_inc calls here but
> * it does not cause any harm since the resulting time when
> --
> 2.9.3
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
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