From: Zlatko Calusic <zcalusic@bitsync.net>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jiri Slaby <jslaby@suse.cz>,
Valdis Kletnieks <Valdis.Kletnieks@vt.edu>,
Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
dormando <dormando@rydia.net>,
Satoru Moriya <satoru.moriya@hds.com>,
Michal Hocko <mhocko@suse.cz>, Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/10] Reduce system disruption due to kswapd V2
Date: Mon, 22 Apr 2013 08:37:03 +0200 [thread overview]
Message-ID: <5174DA8F.2020400@bitsync.net> (raw)
In-Reply-To: <5168699A.40407@bitsync.net>
[-- Attachment #1: Type: text/plain, Size: 1663 bytes --]
On 12.04.2013 22:07, Zlatko Calusic wrote:
> On 12.04.2013 21:40, Mel Gorman wrote:
>> On Thu, Apr 11, 2013 at 10:55:13PM +0200, Zlatko Calusic wrote:
>>> On 09.04.2013 13:06, Mel Gorman wrote:
>>> <SNIP>
>>>
>>> - The only slightly negative thing I observed is that with the patch
>>> applied kswapd burns 10x - 20x more CPU. So instead of about 15
>>> seconds, it has now spent more than 4 minutes on one particular
>>> machine with a quite steady load (after about 12 days of uptime).
>>> Admittedly, that's still nothing too alarming, but...
>>>
>>
>> Would you happen to know what circumstances trigger the higher CPU
>> usage?
>>
>
> Really nothing special. The server is lightly loaded, but it does enough
> reading from the disk so that pagecache is mostly populated and page
> reclaiming is active. So, kswapd is no doubt using CPU time gradually,
> nothing extraordinary.
>
> When I sent my reply yesterday, the server uptime was 12 days, and
> kswapd had accumulated 4:28 CPU time. Now, approx 24 hours later (13
> days uptime):
>
> root 23 0.0 0.0 0 0 ? S Mar30 4:52 [kswapd0]
>
> I will apply your v3 series soon and see if there's any improvement wrt
> CPU usage, although as I said I don't see that as a big issue. It's
> still only 0.013% of available CPU resources (dual core CPU).
>
JFTR, v3 kswapd uses about 15% more CPU time than v2. 2:50 kswapd CPU
time after 6 days 14h uptime.
And find attached another debugging graph that shows how ANON pages are
privileged in the ZONE_NORMAL on a 4GB machine. Take notice that the
number of pages in the ZONE_DMA32 is scaled (/5) to fit the graph nicely.
--
Zlatko
[-- Attachment #2: memdebug-daily.png --]
[-- Type: image/png, Size: 17239 bytes --]
next prev parent reply other threads:[~2013-04-22 6:37 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-09 11:06 [PATCH 0/10] Reduce system disruption due to kswapd V2 Mel Gorman
2013-04-09 11:06 ` [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims at each priority Mel Gorman
2013-04-09 13:27 ` Michal Hocko
2013-04-10 6:47 ` Kamezawa Hiroyuki
2013-04-09 11:06 ` [PATCH 02/10] mm: vmscan: Obey proportional scanning requirements for kswapd Mel Gorman
2013-04-10 7:16 ` Kamezawa Hiroyuki
2013-04-10 14:08 ` Mel Gorman
2013-04-11 0:14 ` Kamezawa Hiroyuki
2013-04-11 9:09 ` Mel Gorman
2013-04-09 11:06 ` [PATCH 03/10] mm: vmscan: Flatten kswapd priority loop Mel Gorman
2013-04-10 7:47 ` Kamezawa Hiroyuki
2013-04-10 13:29 ` Mel Gorman
2013-04-12 2:45 ` Rik van Riel
2013-04-09 11:06 ` [PATCH 04/10] mm: vmscan: Decide whether to compact the pgdat based on reclaim progress Mel Gorman
2013-04-10 8:05 ` Kamezawa Hiroyuki
2013-04-10 13:57 ` Mel Gorman
2013-04-12 2:46 ` Rik van Riel
2013-04-09 11:07 ` [PATCH 05/10] mm: vmscan: Do not allow kswapd to scan at maximum priority Mel Gorman
2013-04-09 11:07 ` [PATCH 06/10] mm: vmscan: Have kswapd writeback pages based on dirty pages encountered, not priority Mel Gorman
2013-04-12 2:51 ` Rik van Riel
2013-04-09 11:07 ` [PATCH 07/10] mm: vmscan: Block kswapd if it is encountering pages under writeback Mel Gorman
2013-04-12 2:54 ` Rik van Riel
2013-04-09 11:07 ` [PATCH 08/10] mm: vmscan: Have kswapd shrink slab only once per priority Mel Gorman
2013-04-09 11:07 ` [PATCH 09/10] mm: vmscan: Check if kswapd should writepage once per pgdat scan Mel Gorman
2013-04-09 11:07 ` [PATCH 10/10] mm: vmscan: Move logic from balance_pgdat() to kswapd_shrink_zone() Mel Gorman
2013-04-12 2:56 ` Rik van Riel
2013-04-09 17:27 ` [PATCH 0/10] Reduce system disruption due to kswapd V2 Christoph Lameter
2013-04-10 14:14 ` Mel Gorman
2013-04-10 22:28 ` dormando
2013-04-10 23:46 ` KOSAKI Motohiro
2013-04-11 9:10 ` Mel Gorman
2013-04-11 20:13 ` Michal Hocko
2013-04-11 20:55 ` Zlatko Calusic
2013-04-12 19:40 ` Mel Gorman
2013-04-12 19:52 ` Mel Gorman
2013-04-12 20:07 ` Zlatko Calusic
2013-04-12 20:41 ` Mel Gorman
2013-04-12 21:14 ` Zlatko Calusic
2013-04-22 6:37 ` Zlatko Calusic [this message]
2013-04-22 6:43 ` Simon Jeons
2013-04-22 6:54 ` Zlatko Calusic
2013-04-22 7:12 ` Simon Jeons
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