From: Phillip Susi <psusi@ubuntu.com>
To: Andrea Righi <andrea@betterlinux.com>
Cc: "Minchan Kim" <minchan@kernel.org>,
linux-mm@kvack.org, "Andrew Morton" <akpm@linux-foundation.org>,
"Pádraig Brady" <P@draigBrady.com>
Subject: Re: [PATCH 1/2] mm: fadvise: fix POSIX_FADV_DONTNEED
Date: Tue, 26 Feb 2013 10:39:40 -0500 [thread overview]
Message-ID: <512CD73C.5010707@ubuntu.com> (raw)
In-Reply-To: <20130226140631.GA2365@thinkpad>
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On 2/26/2013 9:06 AM, Andrea Righi wrote:
> I also like this approach, it looks very similar to the one that I
> proposed a long time ago. However, last time we ended up saying
> that the next step should have been a proposal for a better page
> cache management interface for the userland, adding more fadvise()
> flags, obviously without breaking the current behavior.
If someone wants to add more flags, good for them, but how about we
get the ones we have right first? ;)
> We started with these ideal requirements, but unfortunately I
> didn't go ahead with this project:
> http://marc.info/?l=linux-kernel&m=130917619416123&w=2
>
> About breaking the compatibility, keep in mind that even tools like
> dd, for example, has been modified to support invalidating the
> cache for a file via POSIX_FADV_DONTNEED:
> http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commit;h=5f311553
I
>
don't see how dd would be harmed by this change.
> And it expects to discard cache for the target pages, when
> possible, even if POSIX just says that it will not access the pages
> again any time soon.
Other than the description for the human user, I don't see how it
actually has this expectation.
In fact, when under high cache pressure, the description would still
be essentially correct since the pages will be discarded, just not
necessarily by the time the syscall returns.
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next prev parent reply other threads:[~2013-02-26 15:39 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
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 [this message]
2013-02-23 22:58 ` [PATCH 2/2] mm: fadvise: implement POSIX_FADV_NOREUSE Phillip Susi
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