From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Michel Lespinasse <walken@google.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm: munlock use mapcount to avoid terrible overhead
Date: Tue, 18 Oct 2011 17:56:23 -0700 (PDT) [thread overview]
Message-ID: <alpine.LSU.2.00.1110181752440.4283@sister.anvils> (raw)
In-Reply-To: <20111018171453.53075590.akpm@linux-foundation.org>
On Tue, 18 Oct 2011, Andrew Morton wrote:
> On Tue, 18 Oct 2011 17:02:56 -0700 (PDT)
> Hugh Dickins <hughd@google.com> wrote:
>
> > A process spent 30 minutes exiting, just munlocking the pages of a large
> > anonymous area that had been alternately mprotected into page-sized vmas:
> > for every single page there's an anon_vma walk through all the other
> > little vmas to find the right one.
>
> And how long did the test case take with the patch applied?
5 seconds in the case tried; but the issue is quadratic,
so you can make the improvement look arbitrarily good.
Hugh
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next prev parent reply other threads:[~2011-10-19 0:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-19 0:02 Hugh Dickins
2011-10-19 0:14 ` Andrew Morton
2011-10-19 0:56 ` Hugh Dickins [this message]
2011-10-19 0:25 ` Andi Kleen
2011-10-19 0:59 ` Hugh Dickins
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