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Sender: Ingo Molnar <mingo.kernel.org@gmail.com>
Date:   Tue, 10 Oct 2023 23:45:00 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Raghavendra K T <raghavendra.kt@amd.com>
Cc:     Mel Gorman <mgorman@techsingularity.net>,
        Peter Zijlstra <peterz@infradead.org>,
        K Prateek Nayak <kprateek.nayak@amd.com>,
        Bharata B Rao <bharata@amd.com>,
        Ingo Molnar <mingo@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>
Subject: Re: [PATCH 0/6] sched/numa: Complete scanning of partial and
 inactive VMAs
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References: <20231010083143.19593-1-mgorman@techsingularity.net>
 <793eaa1a-c836-3f0d-7443-b2165a9c6ab9@amd.com>
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* Raghavendra K T <raghavendra.kt@amd.com> wrote:

> On 10/10/2023 2:01 PM, Mel Gorman wrote:
> > NUMA Balancing currently uses PID fault activity within a VMA to
> > determine if it is worth updating PTEs to trap NUMA hinting faults.
> > While this is reduces overhead, it misses two important corner case.
> > The first is that if Task A partially scans a VMA that is active and
> > Task B resumes the scan but is inactive, then the remainder of the VMA
> > may be missed. Similarly, if a VMA is inactive for a period of time then
> > it may never be scanned again.
> > 
> > Patches 1-3 improve the documentation of the current per-VMA tracking
> > and adds a trace point for scan activity. Patch 4 addresses a corner
> > case where the PID activity information may not be reset after the
> > expected timeout. Patches 5-6 complete the scanning of partial and
> > inactive VMAs within the scan sequence.
> > 
> > This could be improved further but it would deserve a separate series on
> > top with supporting data justifying the change. Otherwise and gain/loss
> > due to the additional changes could be masked by this series on its own.
> > 
> 
> Thank you Mel for the patches. I see Ingo already took to sched/core.
> Here is my testing detail FWIW.

Thank you for testing the series, I've added your Tested-by to the final 
two patches that change behavior materially:

   Tested-by: Raghavendra K T <raghavendra.kt@amd.com>

Thanks,

	Ingo