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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>