lkml.org 
[lkml]   [2021]   [Feb]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 0/8] sched/fair: misfit task load-balance tweaks
From
Date
On 03/02/2021 19:43, Valentin Schneider wrote:
> Hi Qais,
>
> On 03/02/21 15:14, Qais Yousef wrote:
>> On 01/28/21 18:31, Valentin Schneider wrote:
>>> Hi folks,
>>>
>>> Here is this year's series of misfit changes. On the menu:
>>>
>>> o Patch 1 is an independent active balance cleanup
>>> o Patch 2 adds some more sched_asym_cpucapacity static branches
>>> o Patch 3 introduces yet another margin for capacity to capacity
>>> comparisons
>>> o Patches 4-6 build on top of patch 3 and change capacity comparisons
>>> throughout misfit load balancing
>>> o Patches 7-8 fix some extra misfit issues I've been seeing on "real"
>>> workloads.
>>>
>>> IMO the somewhat controversial bit is patch 3, because it attempts to solve
>>> margin issues by... Adding another margin. This does solve issues on
>>> existing platforms (e.g. Pixel4), but we'll be back to square one the day
>>> some "clever" folks spin a platform with two different CPU capacities less than
>>> 5% apart.
>>
>> One more margin is a cause of apprehension to me. But in this case I think it
>> is the appropriate thing to do now. I can't think of a scenario where this
>> could hurt.
>>
>
> Thanks for having a look!
>
>> Thanks
>>
>> --
>> Qais Yousef

How did you verify the benefit of these changes?

It's clear that you need a platform with capacity_orig diffs <20%
between CPU types (like Pixel4 - SD855 (4x261, 3x871, 1x1024) or QC's
RB5 platform - SD865 (4x284, 3x871, 1*1024)) but which
benchmark/testcase did you use?

\
 
 \ /
  Last update: 2021-02-04 13:05    [W:0.118 / U:0.692 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site