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From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	torvalds@linux-foundation.org, peterz@infradead.org,
	mingo@kernel.org, aarcange@redhat.com
Subject: Re: [PATCH] sched,numa,mm: revert to checking pmd/pte_write instead of VMA flags
Date: Wed, 14 Sep 2016 10:25:51 +0100	[thread overview]
Message-ID: <20160914092551.GA2745@suse.de> (raw)
In-Reply-To: <1473692983.32433.235.camel@redhat.com>

On Mon, Sep 12, 2016 at 11:09:43AM -0400, Rik van Riel wrote:
> > Patch looks ok other than the comment above the second hunk being out
> > of
> > date. Out of curiousity, what workload benefitted from this? I saw a
> > mix
> > of marginal results when I ran this on a 2-socket and 4-socket box.
> 
> I did not performance test the change, because I believe
> the VM_WRITE test has a small logical error.
> 
> Specifically, VM_WRITE is also true for VMAs that are
> PROT_WRITE|MAP_PRIVATE, which we do NOT want to group
> on. Every shared library mapped on my system seems to
> have a (small) read-write VMA:
> 

Ok, while I agree with you, the patch is not a guaranteed win. However,
in the event it is not, I agree that the problem will be with the
grouping code. If the comment is updated then feel free to add my

Acked-by: Mel Gorman <mgorman@suse.de>

WARNING: multiple messages have this Message-ID (diff)
From: Mel Gorman <mgorman@suse.de>
To: Rik van Riel <riel@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	torvalds@linux-foundation.org, peterz@infradead.org,
	mingo@kernel.org, aarcange@redhat.com
Subject: Re: [PATCH] sched,numa,mm: revert to checking pmd/pte_write instead of VMA flags
Date: Wed, 14 Sep 2016 10:25:51 +0100	[thread overview]
Message-ID: <20160914092551.GA2745@suse.de> (raw)
In-Reply-To: <1473692983.32433.235.camel@redhat.com>

On Mon, Sep 12, 2016 at 11:09:43AM -0400, Rik van Riel wrote:
> > Patch looks ok other than the comment above the second hunk being out
> > of
> > date. Out of curiousity, what workload benefitted from this? I saw a
> > mix
> > of marginal results when I ran this on a 2-socket and 4-socket box.
> 
> I did not performance test the change, because I believe
> the VM_WRITE test has a small logical error.
> 
> Specifically, VM_WRITE is also true for VMAs that are
> PROT_WRITE|MAP_PRIVATE, which we do NOT want to group
> on. Every shared library mapped on my system seems to
> have a (small) read-write VMA:
> 

Ok, while I agree with you, the patch is not a guaranteed win. However,
in the event it is not, I agree that the problem will be with the
grouping code. If the comment is updated then feel free to add my

Acked-by: Mel Gorman <mgorman@suse.de>

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  reply	other threads:[~2016-09-14  9:25 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-09  1:30 [PATCH] sched,numa,mm: revert to checking pmd/pte_write instead of VMA flags Rik van Riel
2016-09-09  1:30 ` Rik van Riel
2016-09-11 16:24 ` Mel Gorman
2016-09-11 16:24   ` Mel Gorman
2016-09-12 15:09   ` Rik van Riel
2016-09-14  9:25     ` Mel Gorman [this message]
2016-09-14  9:25       ` Mel Gorman
2016-09-13 22:07 ` [tip:sched/core] sched/numa, mm: Revert " tip-bot for Rik van Riel

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