From: Hillf Danton <dhillf@gmail.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: hugetlb: defer freeing pages when gathering surplus pages
Date: Wed, 14 Mar 2012 21:08:13 +0800 [thread overview]
Message-ID: <CAJd=RBBd0vF1waARU5FQbomLQLAG5ekmiWg+WDpALke9SaGP1g@mail.gmail.com> (raw)
In-Reply-To: <20120314111357.GD4434@tiehlicka.suse.cz>
On Wed, Mar 14, 2012 at 7:13 PM, Michal Hocko <mhocko@suse.cz> wrote:
> [Sorry for the late reply but I was away from email for quite sometime]
>
Nice to see you back:)
> On Tue 14-02-12 20:53:51, Hillf Danton wrote:
>> When gathering surplus pages, the number of needed pages is recomputed after
>> reacquiring hugetlb lock to catch changes in resv_huge_pages and
>> free_huge_pages. Plus it is recomputed with the number of newly allocated
>> pages involved.
>>
>> Thus freeing pages could be deferred a bit to see if the final page request is
>> satisfied, though pages could be allocated less than needed.
>
> The patch looks OK but I am missing a word why we need it. I guess
False negative is removed as it should be.
> your primary motivation is that we want to reduce false positives when
> we fail to allocate surplus pages while somebody freed some in the
> background.
> What is the workload that you observed such a behavior? Or is this just
> from the code review?
>
The second.
-hd
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next prev parent reply other threads:[~2012-03-14 13:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-14 12:53 Hillf Danton
2012-03-14 11:13 ` Michal Hocko
2012-03-14 13:08 ` Hillf Danton [this message]
2012-03-15 14:44 ` Michal Hocko
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