From: Phillip Susi <psusi@ubuntu.com>
To: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: linux-mm@kvack.org
Subject: Re: [PATCH 1/2] mm: fadvise: fix POSIX_FADV_DONTNEED
Date: Sun, 24 Feb 2013 17:38:18 -0500 [thread overview]
Message-ID: <512A965A.6060201@ubuntu.com> (raw)
In-Reply-To: <512A8550.2040200@linux.vnet.ibm.com>
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On 02/24/2013 04:25 PM, Dave Hansen wrote:
> Essentially, they don't want any I/O initiated except that which
> is initiated by the app. If you let the system get in to reclaim,
> it'll start doing dirty writeout for pages other than those the app
> is interested in.
Are you talking about IO initiated by the app, or other tasks in the
system? If the former then it won't be affected by this change. For
the latter, you don't really have control over that now since the
pages very well may cause other writeouts before you get around to
calling fadvise. The extent to which the fadvise call mitigates
pushing writes from other applications out of the cache is only
slightly affected by this patch. Specifically it may cause other
pages that already got pushed to the inactive list to be flushed, but
they were already very close to that before.
If you use POSIX_FADV_NOREUSE instead, then you will end up at least
as well off as before, possibly better since it takes effect at write
time instead of some later call to fadvise, after having synced the pages.
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next prev parent reply other threads:[~2013-02-24 22:38 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-22 19:57 POSIX_FADV_DONTNEED implemented wrong Phillip Susi
2013-02-22 20:29 ` Johannes Weiner
2013-02-22 21:52 ` Phillip Susi
2013-02-23 22:57 ` [PATCH 0/2] FADV_DONTNEED and FADV_NOREUSE Phillip Susi
2013-02-23 22:58 ` [PATCH 1/2] mm: fadvise: fix POSIX_FADV_DONTNEED Phillip Susi
2013-02-24 1:46 ` Dave Hansen
2013-02-24 3:37 ` Phillip Susi
2013-02-24 18:24 ` Dave Hansen
2013-02-24 20:40 ` Phillip Susi
2013-02-24 21:25 ` Dave Hansen
2013-02-24 22:38 ` Phillip Susi [this message]
2013-02-25 17:50 ` Dave Hansen
2013-02-24 3:58 ` Zheng Liu
2013-02-24 4:04 ` Phillip Susi
2013-02-26 4:21 ` Minchan Kim
2013-02-26 14:06 ` Andrea Righi
2013-02-26 15:39 ` Phillip Susi
2013-02-23 22:58 ` [PATCH 2/2] mm: fadvise: implement POSIX_FADV_NOREUSE Phillip Susi
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