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Message-ID: <3c92c18b-6a19-4477-9972-1219c29b3d71@linux.ibm.com>
Date: Mon, 25 Mar 2024 17:03:10 +0530
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Subject: Re: [PATCH v3 0/2] sched: Minor changes for rd->overload access
To: Ingo Molnar <mingo@kernel.org>
Cc: peterz@infradead.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        qyousef@layalina.io, linux-kernel@vger.kernel.org, vschneid@redhat.com
References: <20240325054505.201995-1-sshegde@linux.ibm.com>
 <ZgFTtAOw39tIyfzR@gmail.com>
From: Shrikanth Hegde <sshegde@linux.ibm.com>
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On 3/25/24 4:06 PM, Ingo Molnar wrote:
> 
> * Shrikanth Hegde <sshegde@linux.ibm.com> wrote:
> 
>> v2 -> v3:
>> - Wrapped check for value change inside ser_rd_overload_status
>>   as suggested by Qais.
>> - Added reviewed-by tags.
>>
>> v1 -> v2:
>> - dropped Fixes tag.
>> - Added one of the perf probes in the changelog for reference.
>> - Added reviewed-by tags.
>>
>> tl;dr
>> When running workloads in large systems, it was observed that access to
>> rd->overload was taking time. It would be better to check the value
>> before updating since value changes less often. Patch 1/2 does that.
>> With patch updates happen only if necessary. CPU Bus traffic reduced a
>> bit. No significant gains in workload performance.
> 
> Could you please post this against the latest scheduler tree, ie. tip:sched/core?
> 
> Thanks,
> 
> 	Ingo

Hi Ingo. I had mentioned the same in cover letter. Sorry if I didn't 
mention it in the correct place. 

*These patches depend on below to be applied first*
https://lore.kernel.org/all/20240307085725.444486-1-sshegde@linux.ibm.com/

After that the above patch would apply. I kept the dependency since these are in similar 
code area. Can we please consider the above patch as well? Is there any other change that needs 
to be done? 

On tip
1043c003415b (HEAD -> master) sched/fair: Use helper functions to access rd->overload
3049bc16643d sched/fair: Check rd->overload value before update
436d634f2cad sched/fair: Combine EAS check with overutilized access
379aa2cd62e0 sched/fair: Use helper function to access rd->overutilized
19bfeb2d565e sched/fair: Add EAS checks before updating overutilized
71706005072c (origin/master, origin/HEAD) Merge branch into tip/master: 'x86/shstk'


fa63c2c111ea (HEAD -> sched/core) sched/fair: Use helper functions to access rd->overload
9bef486d044b sched/fair: Check rd->overload value before update
21f90cae75c8 sched/fair: Combine EAS check with overutilized access
e835f1fa3654 sched/fair: Use helper function to access rd->overutilized
ddf390f9449d sched/fair: Add EAS checks before updating overutilized
58eeb2d79b54 (origin/sched/core) sched/fair: Don't double balance_interval for migrate_misfit