Re: [REGRESSION] sched/fair: Add lag based placement
From: Phil Auld
Date: Wed Nov 13 2024 - 13:20:01 EST
Hi,
On Wed, Nov 13, 2024 at 01:03:00PM -0500 Joseph Salisbury wrote:
> Hello,
>
> During performance testing, we found a regression of ~9% performance with
> the TPCC benchmark. This performance regression was introduced in
> v6.6-rc1. After a bisect, the following commit was identified as the cause
> of the regression:
>
> 86bfbb7ce4f6 ("sched/fair: Add lag based placement")
>
> I was hoping to get some feedback from the scheduler folks. Do you think
> gathering any additional data will help diagnose this issue? Are there any
> tunable options that can changed to see how performance is affected?
>
You can try turning off the PLACE_LAG sched feature:
echo NO_PLACE_LAG > /sys/kernel/debug/sched/features
It's not what I'd call a tunable but it would allow you to test w/o it and
see what it does. It should allow you to switch back and forth easily for
testing.
Cheers,
Phil
>
> Thanks,
>
> Joe
>
>
>
>
>
>
>
>
--