From: Dave Hansen <dave.hansen@intel.com>
To: Mel Gorman <mgorman@suse.de>, linux-mm@kvack.org
Cc: Minchan Kim <minchan@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] mm: madvise: Ignore repeated MADV_DONTNEED hints
Date: Mon, 02 Feb 2015 14:22:36 -0800 [thread overview]
Message-ID: <54CFF8AC.6010102@intel.com> (raw)
In-Reply-To: <20150202165525.GM2395@suse.de>
On 02/02/2015 08:55 AM, Mel Gorman wrote:
> This patch identifies when a thread is frequently calling MADV_DONTNEED
> on the same region of memory and starts ignoring the hint. On an 8-core
> single-socket machine this was the impact on ebizzy using glibc 2.19.
The manpage, at least, claims that we zero-fill after MADV_DONTNEED is
called:
> MADV_DONTNEED
> Do not expect access in the near future. (For the time being, the application is finished with the given range, so the kernel can free resources
> associated with it.) Subsequent accesses of pages in this range will succeed, but will result either in reloading of the memory contents from the
> underlying mapped file (see mmap(2)) or zero-fill-on-demand pages for mappings without an underlying file.
So if we have anything depending on the behavior that it's _always_
zero-filled after an MADV_DONTNEED, this will break it.
WARNING: multiple messages have this Message-ID (diff)
From: Dave Hansen <dave.hansen@intel.com>
To: Mel Gorman <mgorman@suse.de>, linux-mm@kvack.org
Cc: Minchan Kim <minchan@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] mm: madvise: Ignore repeated MADV_DONTNEED hints
Date: Mon, 02 Feb 2015 14:22:36 -0800 [thread overview]
Message-ID: <54CFF8AC.6010102@intel.com> (raw)
In-Reply-To: <20150202165525.GM2395@suse.de>
On 02/02/2015 08:55 AM, Mel Gorman wrote:
> This patch identifies when a thread is frequently calling MADV_DONTNEED
> on the same region of memory and starts ignoring the hint. On an 8-core
> single-socket machine this was the impact on ebizzy using glibc 2.19.
The manpage, at least, claims that we zero-fill after MADV_DONTNEED is
called:
> MADV_DONTNEED
> Do not expect access in the near future. (For the time being, the application is finished with the given range, so the kernel can free resources
> associated with it.) Subsequent accesses of pages in this range will succeed, but will result either in reloading of the memory contents from the
> underlying mapped file (see mmap(2)) or zero-fill-on-demand pages for mappings without an underlying file.
So if we have anything depending on the behavior that it's _always_
zero-filled after an MADV_DONTNEED, this will break it.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-02-02 22:22 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-02 16:55 [RFC PATCH] mm: madvise: Ignore repeated MADV_DONTNEED hints Mel Gorman
2015-02-02 16:55 ` Mel Gorman
2015-02-02 22:05 ` Andrew Morton
2015-02-02 22:05 ` Andrew Morton
2015-02-02 22:18 ` Mel Gorman
2015-02-02 22:18 ` Mel Gorman
2015-02-02 22:35 ` Andrew Morton
2015-02-02 22:35 ` Andrew Morton
2015-02-03 0:26 ` Davidlohr Bueso
2015-02-03 0:26 ` Davidlohr Bueso
2015-02-03 10:50 ` Mel Gorman
2015-02-03 10:50 ` Mel Gorman
2015-02-05 21:44 ` Rik van Riel
2015-02-05 21:44 ` Rik van Riel
2015-02-02 22:22 ` Dave Hansen [this message]
2015-02-02 22:22 ` Dave Hansen
2015-02-03 8:19 ` MADV_DONTNEED semantics? Was: " Vlastimil Babka
2015-02-03 8:19 ` Vlastimil Babka
2015-02-03 10:53 ` Kirill A. Shutemov
2015-02-03 10:53 ` Kirill A. Shutemov
2015-02-03 10:53 ` Kirill A. Shutemov
2015-02-03 11:42 ` Vlastimil Babka
2015-02-03 11:42 ` Vlastimil Babka
2015-02-03 16:20 ` Michael Kerrisk (man-pages)
2015-02-03 16:20 ` Michael Kerrisk (man-pages)
2015-02-04 13:46 ` Vlastimil Babka
2015-02-04 13:46 ` Vlastimil Babka
2015-02-04 13:46 ` Vlastimil Babka
2015-02-04 14:00 ` Michael Kerrisk (man-pages)
2015-02-04 14:00 ` Michael Kerrisk (man-pages)
2015-02-04 14:00 ` Michael Kerrisk (man-pages)
2015-02-04 17:02 ` Vlastimil Babka
2015-02-04 17:02 ` Vlastimil Babka
2015-02-04 19:24 ` Michael Kerrisk (man-pages)
2015-02-04 19:24 ` Michael Kerrisk (man-pages)
2015-02-04 19:24 ` Michael Kerrisk (man-pages)
2015-02-05 1:07 ` Minchan Kim
2015-02-05 1:07 ` Minchan Kim
2015-02-05 1:07 ` Minchan Kim
2015-02-06 15:41 ` Michael Kerrisk (man-pages)
2015-02-06 15:41 ` Michael Kerrisk (man-pages)
2015-02-06 15:41 ` Michael Kerrisk (man-pages)
2015-02-09 6:46 ` Minchan Kim
2015-02-09 6:46 ` Minchan Kim
2015-02-09 6:46 ` Minchan Kim
2015-02-09 9:13 ` Michael Kerrisk (man-pages)
2015-02-09 9:13 ` Michael Kerrisk (man-pages)
2015-02-05 15:41 ` Michal Hocko
2015-02-05 15:41 ` Michal Hocko
2015-02-05 15:41 ` Michal Hocko
2015-02-06 15:57 ` Michael Kerrisk (man-pages)
2015-02-06 15:57 ` Michael Kerrisk (man-pages)
2015-02-06 15:57 ` Michael Kerrisk (man-pages)
2015-02-06 20:45 ` Michal Hocko
2015-02-06 20:45 ` Michal Hocko
2015-02-06 20:45 ` Michal Hocko
2015-02-09 6:50 ` Minchan Kim
2015-02-09 6:50 ` Minchan Kim
2015-02-09 6:50 ` Minchan Kim
2015-02-04 0:09 ` Minchan Kim
2015-02-04 0:09 ` Minchan Kim
2015-02-04 0:09 ` Minchan Kim
2015-02-03 11:16 ` Mel Gorman
2015-02-03 11:16 ` Mel Gorman
2015-02-03 15:21 ` Michal Hocko
2015-02-03 15:21 ` Michal Hocko
2015-02-03 15:21 ` Michal Hocko
2015-02-03 16:25 ` Michael Kerrisk (man-pages)
2015-02-03 16:25 ` Michael Kerrisk (man-pages)
2015-02-03 16:25 ` Michael Kerrisk (man-pages)
2015-02-03 9:47 ` Mel Gorman
2015-02-03 9:47 ` Mel Gorman
2015-02-03 10:47 ` Kirill A. Shutemov
2015-02-03 10:47 ` Kirill A. Shutemov
2015-02-03 11:21 ` Mel Gorman
2015-02-03 11:21 ` Mel Gorman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=54CFF8AC.6010102@intel.com \
--to=dave.hansen@intel.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mgorman@suse.de \
--cc=minchan@kernel.org \
--cc=vbabka@suse.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.