linux-kernel - Re: [PATCH 00/30] PREEMPT_AUTO: support lazy rescheduling

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Date: Thu, 22 Feb 2024 09:35:58 +0530
From: Raghavendra K T <raghavendra.kt@....com>
To: Ankur Arora <ankur.a.arora@...cle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
 peterz@...radead.org, torvalds@...ux-foundation.org, paulmck@...nel.org,
 akpm@...ux-foundation.org, luto@...nel.org, bp@...en8.de,
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 mgorman@...e.de, jpoimboe@...nel.org, mark.rutland@....com, jgross@...e.com,
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 David.Laight@...LAB.COM, richard@....at, mjguzik@...il.com,
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 konrad.wilk@...cle.com
Subject: Re: [PATCH 00/30] PREEMPT_AUTO: support lazy rescheduling

On 2/22/2024 2:46 AM, Ankur Arora wrote:
> 
> Raghavendra K T <raghavendra.kt@....com> writes:
> 
>> On 2/21/2024 10:45 PM, Thomas Gleixner wrote:
>>> On Wed, Feb 21 2024 at 17:53, Raghavendra K T wrote:
>>>> Configuration tested.
>>>> a) Base kernel (6.7),
>>> Which scheduling model is the baseline using?
>>>
>>
>> baseline is also PREEMPT_DYNAMIC with voluntary preemption
>>
>>>> b) patched with PREEMPT_AUTO voluntary preemption.
>>>> c) patched with PREEMPT_DYNAMIC voluntary preemption.
>>>>
>>>> Workloads I tested and their %gain,
>>>>                       case b                   case c
>>>> NAS                +2.7                    +1.9
>>>> Hashjoin,          +0			     +0
>>>> XSBench	     +1.7		     +0
>>>> Graph500,  	     -6 		     +0
>>> The Graph500 stands out. Needs some analysis.
>>>
>>
>> Sure. Will do more detailed analysis and comeback on this.
> 
> Thanks Raghu. Please keep me posted.
> 
> Also, let me try to reproduce this locally. Could you post the
> parameters that you used for the Graph500 run?
> 

This was run as part of test suite where by from output, Parameters, I 
see as :

SCALE: 27
nvtx: 134217728
edgefactor: 16
terasize: 3.43597383679999993e-02
A: 5.69999999999999951e-01
B: 1.90000000000000002e-01
C: 1.90000000000000002e-01
D: 5.00000000000000444e-02
generation_time: 4.93902114900000022e+00
construction_time: 2.55216929010000015e+01
nbfs: 64

Meanwhile since stddev for the runs I saw was little bit on higher side,
I did think results are Okay.

Rerunning with more iterations to see if there is a valid concern, if so 
I will dig more deep as Thomas pointed.
Also will post the results of run.

Thanks and Regards
- Raghu