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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
Date: Tue, 10 Oct 2023 23:45:00 +0200	[thread overview]
Message-ID: <ZSXF3AFZgIld1meX@gmail.com> (raw)
In-Reply-To: <793eaa1a-c836-3f0d-7443-b2165a9c6ab9@amd.com>


* 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


      reply	other threads:[~2023-10-10 21:45 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-10  8:31 Mel Gorman
2023-10-10  8:31 ` [PATCH 1/6] sched/numa: Document vma_numab_state fields Mel Gorman
2023-10-10  8:31 ` [PATCH 2/6] sched/numa: Rename vma_numab_state.access_pids Mel Gorman
2023-10-10  8:31 ` [PATCH 3/6] sched/numa: Trace decisions related to skipping VMAs Mel Gorman
2023-10-10  8:31 ` [PATCH 4/6] sched/numa: Move up the access pid reset logic Mel Gorman
2023-10-10  8:31 ` [PATCH 5/6] sched/numa: Complete scanning of partial VMAs regardless of PID activity Mel Gorman
2023-10-10  8:31 ` [PATCH 6/6] sched/numa: Complete scanning of inactive VMAs when there is no alternative Mel Gorman
2023-10-10  9:23   ` Ingo Molnar
2023-10-10  9:57     ` Mel Gorman
2023-10-10 21:39       ` Ingo Molnar
2023-10-10 11:40     ` Raghavendra K T
2024-02-24  4:50       ` Raghavendra K T
2023-10-10 11:42   ` Raghavendra K T
2023-10-10 11:39 ` [PATCH 0/6] sched/numa: Complete scanning of partial and inactive VMAs Raghavendra K T
2023-10-10 21:45   ` Ingo Molnar [this message]

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