From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Phillip Susi <psusi@ubuntu.com>
Cc: linux-mm@kvack.org
Subject: Re: [PATCH 1/2] mm: fadvise: fix POSIX_FADV_DONTNEED
Date: Sat, 23 Feb 2013 17:46:55 -0800 [thread overview]
Message-ID: <5129710F.6060804@linux.vnet.ibm.com> (raw)
In-Reply-To: <1361660281-22165-2-git-send-email-psusi@ubuntu.com>
On 02/23/2013 02:58 PM, Phillip Susi wrote:
> 2) Discarding pages under low cache pressure is a waste
> 3) It was useless on files being written, and thus full of dirty pages
>
> Now we just move the pages to the inactive list so they will be reclaimed
> sooner.
Folks actually use this in practice to flush the page cache out:
http://git.sr71.net/?p=eyefi-config.git;a=blob;f=eyefi-linux.c;h=b77a891995109f6caa288925a13985cc495d7b2d;hb=HEAD#l62
I have really good reasons for really wanting to be _rid_ of the page
cache no matter how much memory pressure there is.
I've seen people at IBM using this to ensure that they stay out of
memory reclaim completely. I don't completely agree with the approach,
but this would completely ruin their performance since the VM-initiated
writeout is so relatively slow for them.
I think this patch is a really bad idea. If you want the behavior
you're proposing, I'd suggest using another flag.
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next prev parent reply other threads:[~2013-02-24 1:47 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 [this message]
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
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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