From: Mel Gorman <mel@csn.ul.ie>
To: Shaohua Li <shaohua.li@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
"Chen, Tim C" <tim.c.chen@intel.com>,
Rik van Riel <riel@redhat.com>, "Shi, Alex" <alex.shi@intel.com>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: too big min_free_kbytes
Date: Fri, 25 Feb 2011 12:13:53 +0000 [thread overview]
Message-ID: <20110225121352.GA8010@csn.ul.ie> (raw)
In-Reply-To: <1298595109.19589.46.camel@sli10-conroe>
On Fri, Feb 25, 2011 at 08:51:49AM +0800, Shaohua Li wrote:
> On Thu, 2011-02-24 at 22:04 +0800, Andrea Arcangeli wrote:
> > On Thu, Feb 24, 2011 at 04:08:47PM +0800, Shaohua Li wrote:
> > > with madvise, the min_free_kbytes is still high (same as the 'always'
> > > case). The result is still we have about 50M memory is reserved. you can
> > > try at your machine with boot option 'mem=2G' and check the zoneinfo
> > > output.
> >
> > yes I know. The objective of that test was exactly to know if the
> > problem is higher memory footprint because of THP or only the
> > anti-frag/min_free_kbytes which would still be present with the
> > "madvise" setting (anti-frag is only shutdown by the "never"
> > setting). If you still have the out of memory with madvise, then you
> > can keep THP enabled "always" and then "echo 16384 >
> > /proc/sys/vm/min_free_kbytes", it should work fine then even with THP
> > always mode then, no need to disable THP (simply you won't have a good
> > guarantee that anti-frag is functional so the hugepage usage will be
> > reduced over time compared to the default min_free_kbytes that enables
> > anti-frag fully).
>
> I can disable THP or set the min_free_kbytes manually in our test, but
> just wonder if it's possible we can avoid the memory waste even with THP
> enabled, because this will make more people enable it by default.
With a lower value of min_free_kbytes, THP would give diminishing returns
over time as hugepage allocation success rates start degrading over time. It
might not happen for several days or weeks making it a tricky problem to
diagnose. So yes, the memory waste with THP enabled can be fixed but it
would only be suitable for short-term benchmarks.
> If you
> don't consider this is a problem, we can disable THP.
>
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2011-02-25 12:14 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-24 3:56 too big min_free_kbytes Shaohua Li
2011-01-24 15:00 ` Andrea Arcangeli
2011-01-25 14:35 ` Mel Gorman
2011-01-26 14:17 ` Mel Gorman
2011-01-26 15:23 ` Mel Gorman
2011-01-26 15:42 ` Andrea Arcangeli
2011-01-26 16:36 ` Mel Gorman
2011-01-26 17:42 ` Mel Gorman
2011-01-27 13:40 ` Mel Gorman
2011-01-27 15:27 ` Andrea Arcangeli
2011-01-27 16:03 ` Mel Gorman
2011-01-27 18:52 ` Andrea Arcangeli
2011-01-27 20:33 ` Rik van Riel
2011-01-27 21:31 ` Mel Gorman
2011-01-27 23:18 ` Rik van Riel
2011-01-28 10:35 ` Mel Gorman
2011-01-28 16:28 ` Andrea Arcangeli
2011-01-28 16:46 ` Mel Gorman
2011-01-28 17:16 ` Rik van Riel
2011-01-28 17:46 ` Andrea Arcangeli
2011-01-28 18:03 ` Rik van Riel
2011-01-28 18:24 ` Andrea Arcangeli
2011-01-28 19:34 ` Rik van Riel
2011-01-28 19:45 ` Andrea Arcangeli
2011-01-28 20:55 ` Rik van Riel
2011-01-29 19:45 ` Andrea Arcangeli
2011-01-28 17:34 ` Andrea Arcangeli
2011-01-28 17:10 ` Rik van Riel
2011-02-03 2:58 ` Andrea Arcangeli
2011-02-03 13:15 ` Mel Gorman
2011-02-03 18:59 ` Andrea Arcangeli
2011-02-03 14:36 ` Rik van Riel
2011-02-03 19:11 ` Andrea Arcangeli
2011-02-12 1:28 ` Simon Kirby
2011-02-14 2:25 ` Shaohua Li
2011-02-22 14:25 ` Mel Gorman
2011-02-22 14:42 ` Andrea Arcangeli
2011-02-22 14:50 ` Mel Gorman
2011-02-22 14:54 ` Andrea Arcangeli
2011-02-22 16:04 ` Mel Gorman
2011-02-22 16:40 ` Rik van Riel
2011-02-23 5:29 ` Shaohua Li
2011-02-23 14:45 ` Andrea Arcangeli
2011-02-24 8:08 ` Shaohua Li
2011-02-24 9:52 ` Mel Gorman
2011-02-24 9:57 ` Mel Gorman
2011-02-24 14:27 ` Andrea Arcangeli
2011-02-24 14:04 ` Andrea Arcangeli
2011-02-25 0:51 ` Shaohua Li
2011-02-25 12:13 ` Mel Gorman [this message]
2011-02-12 9:48 ` alex shi
2011-02-22 14:24 ` Mel Gorman
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