From: Rik van Riel <riel@redhat.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Satoru Moriya <satoru.moriya@hds.com>,
Mel Gorman <mgorman@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [patch 2/8] mm: vmscan: disregard swappiness shortly before going OOM
Date: Fri, 14 Dec 2012 10:43:55 -0500 [thread overview]
Message-ID: <50CB493B.8000900@redhat.com> (raw)
In-Reply-To: <20121214083738.GA6898@dhcp22.suse.cz>
On 12/14/2012 03:37 AM, Michal Hocko wrote:
> I can answer the later. Because memsw comes with its price and
> swappiness is much cheaper. On the other hand it makes sense that
> swappiness==0 doesn't swap at all. Or do you think we should get back to
> _almost_ doesn't swap at all?
swappiness==0 will swap in emergencies, specifically when we have
almost no page cache left, we will still swap things out:
if (global_reclaim(sc)) {
free = zone_page_state(zone, NR_FREE_PAGES);
if (unlikely(file + free <= high_wmark_pages(zone))) {
/*
* If we have very few page cache pages, force-scan
* anon pages.
*/
fraction[0] = 1;
fraction[1] = 0;
denominator = 1;
goto out;
This makes sense, because people who set swappiness==0 but
do have swap space available would probably prefer some
emergency swapping over an OOM kill.
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WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Satoru Moriya <satoru.moriya@hds.com>,
Mel Gorman <mgorman@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [patch 2/8] mm: vmscan: disregard swappiness shortly before going OOM
Date: Fri, 14 Dec 2012 10:43:55 -0500 [thread overview]
Message-ID: <50CB493B.8000900@redhat.com> (raw)
In-Reply-To: <20121214083738.GA6898@dhcp22.suse.cz>
On 12/14/2012 03:37 AM, Michal Hocko wrote:
> I can answer the later. Because memsw comes with its price and
> swappiness is much cheaper. On the other hand it makes sense that
> swappiness==0 doesn't swap at all. Or do you think we should get back to
> _almost_ doesn't swap at all?
swappiness==0 will swap in emergencies, specifically when we have
almost no page cache left, we will still swap things out:
if (global_reclaim(sc)) {
free = zone_page_state(zone, NR_FREE_PAGES);
if (unlikely(file + free <= high_wmark_pages(zone))) {
/*
* If we have very few page cache pages, force-scan
* anon pages.
*/
fraction[0] = 1;
fraction[1] = 0;
denominator = 1;
goto out;
This makes sense, because people who set swappiness==0 but
do have swap space available would probably prefer some
emergency swapping over an OOM kill.
--
All rights reversed
next prev parent reply other threads:[~2012-12-14 15:44 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-12 21:43 [patch 0/8] page reclaim bits Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 21:43 ` [patch 1/8] mm: memcg: only evict file pages when we have plenty Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 21:53 ` Rik van Riel
2012-12-12 21:53 ` Rik van Riel
2012-12-12 22:28 ` Johannes Weiner
2012-12-12 22:28 ` Johannes Weiner
2012-12-13 10:07 ` Mel Gorman
2012-12-13 10:07 ` Mel Gorman
2012-12-13 14:44 ` Mel Gorman
2012-12-13 14:44 ` Mel Gorman
2012-12-13 14:55 ` Michal Hocko
2012-12-13 14:55 ` Michal Hocko
2012-12-16 1:21 ` Simon Jeons
2012-12-16 1:21 ` Simon Jeons
2012-12-17 15:54 ` Michal Hocko
2012-12-17 15:54 ` Michal Hocko
2012-12-19 5:21 ` Simon Jeons
2012-12-19 5:21 ` Simon Jeons
2012-12-19 9:20 ` Mel Gorman
2012-12-19 9:20 ` Mel Gorman
2012-12-13 5:36 ` Simon Jeons
2012-12-13 5:36 ` Simon Jeons
2012-12-13 5:34 ` Simon Jeons
2012-12-13 5:34 ` Simon Jeons
2012-12-12 21:43 ` [patch 2/8] mm: vmscan: disregard swappiness shortly before going OOM Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:01 ` Rik van Riel
2012-12-12 22:01 ` Rik van Riel
2012-12-13 5:56 ` Simon Jeons
2012-12-13 5:56 ` Simon Jeons
2012-12-13 10:34 ` Mel Gorman
2012-12-13 10:34 ` Mel Gorman
2012-12-13 15:29 ` Michal Hocko
2012-12-13 15:29 ` Michal Hocko
2012-12-13 16:05 ` Michal Hocko
2012-12-13 16:05 ` Michal Hocko
2012-12-13 22:25 ` Satoru Moriya
2012-12-13 22:25 ` Satoru Moriya
2012-12-14 4:50 ` Johannes Weiner
2012-12-14 4:50 ` Johannes Weiner
2012-12-14 8:37 ` Michal Hocko
2012-12-14 8:37 ` Michal Hocko
2012-12-14 15:43 ` Rik van Riel [this message]
2012-12-14 15:43 ` Rik van Riel
2012-12-14 16:13 ` Michal Hocko
2012-12-14 16:13 ` Michal Hocko
2012-12-15 0:18 ` Johannes Weiner
2012-12-15 0:18 ` Johannes Weiner
2012-12-17 16:37 ` Michal Hocko
2012-12-17 16:37 ` Michal Hocko
2012-12-17 17:54 ` Johannes Weiner
2012-12-17 17:54 ` Johannes Weiner
2012-12-17 19:58 ` Michal Hocko
2012-12-17 19:58 ` Michal Hocko
2012-12-14 20:17 ` Satoru Moriya
2012-12-14 20:17 ` Satoru Moriya
2012-12-14 19:44 ` Satoru Moriya
2012-12-14 19:44 ` Satoru Moriya
2012-12-13 19:05 ` Johannes Weiner
2012-12-13 19:05 ` Johannes Weiner
2012-12-13 19:47 ` Mel Gorman
2012-12-13 19:47 ` Mel Gorman
2012-12-12 21:43 ` [patch 3/8] mm: vmscan: save work scanning (almost) empty LRU lists Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:02 ` Rik van Riel
2012-12-12 22:02 ` Rik van Riel
2012-12-13 10:41 ` Mel Gorman
2012-12-13 10:41 ` Mel Gorman
2012-12-13 19:33 ` Johannes Weiner
2012-12-13 19:33 ` Johannes Weiner
2012-12-13 15:43 ` Michal Hocko
2012-12-13 15:43 ` Michal Hocko
2012-12-13 19:38 ` Johannes Weiner
2012-12-13 19:38 ` Johannes Weiner
2012-12-14 8:46 ` Michal Hocko
2012-12-14 8:46 ` Michal Hocko
2012-12-12 21:43 ` [patch 4/8] mm: vmscan: clarify LRU balancing close to OOM Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:03 ` Rik van Riel
2012-12-12 22:03 ` Rik van Riel
2012-12-13 10:46 ` Mel Gorman
2012-12-13 10:46 ` Mel Gorman
2012-12-12 21:43 ` [patch 5/8] mm: vmscan: improve comment on low-page cache handling Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:04 ` Rik van Riel
2012-12-12 22:04 ` Rik van Riel
2012-12-13 10:47 ` Mel Gorman
2012-12-13 10:47 ` Mel Gorman
2012-12-13 16:07 ` Michal Hocko
2012-12-13 16:07 ` Michal Hocko
2012-12-12 21:43 ` [patch 6/8] mm: vmscan: clean up get_scan_count() Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:06 ` Rik van Riel
2012-12-12 22:06 ` Rik van Riel
2012-12-13 11:07 ` Mel Gorman
2012-12-13 11:07 ` Mel Gorman
2012-12-13 16:18 ` Michal Hocko
2012-12-13 16:18 ` Michal Hocko
2012-12-12 21:43 ` [patch 7/8] mm: vmscan: compaction works against zones, not lruvecs Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:31 ` Rik van Riel
2012-12-12 22:31 ` Rik van Riel
2012-12-13 11:12 ` Mel Gorman
2012-12-13 11:12 ` Mel Gorman
2012-12-13 16:48 ` Michal Hocko
2012-12-13 16:48 ` Michal Hocko
2012-12-12 21:43 ` [patch 8/8] mm: reduce rmap overhead for ex-KSM page copies created on swap faults Johannes Weiner
2012-12-12 21:43 ` Johannes Weiner
2012-12-12 22:34 ` Rik van Riel
2012-12-12 22:34 ` Rik van Riel
2012-12-12 21:50 ` [patch 0/8] page reclaim bits Andrew Morton
2012-12-12 21:50 ` Andrew Morton
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