lkml.org 
[lkml]   [2019]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] schied/fair: Skip updating "contrib" without load
On Sat, Dec 07, 2019 at 12:14:22AM +0800, Peng Wang wrote:
> We only update load_sum/runnable_load_sum/util_sum with
> decayed old sum when load is clear.

What you're saying is that because of the:

if (!load)
runnable = running = 0;

clause in ___update_load_sum(), all the actual users of @contrib in
accumulate_sum():

if (load)
sa->load_sum += load * contrib;
if (runnable)
sa->runnable_load_sum += runnable * contrib;
if (running)
sa->util_sum += contrib << SCHED_CAPACITY_SHIFT;

don't happen, and therefore we don't care what @contrib actually is and
calculating it is pointless.

I suppose that is so. did you happen to have performance numbers? Also,
I'm thinking this wants a comment.

> Signed-off-by: Peng Wang <rocking@linux.alibaba.com>
> ---
> kernel/sched/pelt.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
> index a96db50..4392953 100644
> --- a/kernel/sched/pelt.c
> +++ b/kernel/sched/pelt.c
> @@ -129,8 +129,9 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
> * Step 2
> */
> delta %= 1024;
> - contrib = __accumulate_pelt_segments(periods,
> - 1024 - sa->period_contrib, delta);
> + if (load)
> + contrib = __accumulate_pelt_segments(periods,
> + 1024 - sa->period_contrib, delta);
> }
> sa->period_contrib = delta;
>
> --
> 1.8.3.1
>

\
 
 \ /
  Last update: 2019-12-09 17:17    [W:0.131 / U:0.320 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site