lkml.org 
[lkml]   [2013]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/10] Reduce system disruption due to kswapd V2
On Fri, Apr 12, 2013 at 10:07:54PM +0200, 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]
>

Ok, that's not too crazy.

> 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).
>

Excellent, thanks very much for testing and reporting back. I read your
mail on the zone balancing and FWIW I would not have expected this series
to have any impact on it. I do not have a good theory yet as to what the
problem is but I'll give it some thought and se what I come up with. I'll
be at LSF/MM next week so it might take me a while.

--
Mel Gorman
SUSE Labs


\
 
 \ /
  Last update: 2013-04-12 23:21    [W:0.120 / U:0.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site