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Date: Fri, 26 Aug 2011 11:30:35 +0800 From: Zhu Yanhai <zhu.yanhai@...il.com> To: Wu Fengguang <fengguang.wu@...el.com> Cc: Stefan Priebe <s.priebe@...fihost.ag>, Pekka Enberg <penberg@...nel.org>, LKML <linux-kernel@...r.kernel.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, Mel Gorman <mel@....ul.ie>, Jens Axboe <jaxboe@...ionio.com>, Linux Netdev List <netdev@...r.kernel.org> Subject: Re: slow performance on disk/network i/o full speed after drop_caches Fengguang, Maybe it's because zone_reclaim_mode? We often have received some reports that scp or something like that is slow with no reason, and mostly it's due to someone enabled zone_reclaim_mode by mistake. Stefan, is your zone_reclaim_mode enabled? try 'cat /proc/sys/vm/zone_reclaim_mode', and echo 0 to it to disable. Thanks, Zhu Yanhai 2011/8/26 Wu Fengguang <fengguang.wu@...el.com>: > On Fri, Aug 26, 2011 at 11:13:07AM +0800, Stefan Priebe wrote: >> >> >> There is at least a numastat proc file. >> > >> > Thanks. This shows that node0 is accessed 10x more than node1. >> >> What can i do to prevent this or isn't this normal when a machine mostly idles so processes are mostly processed by cpu0. > > Yes, that's normal. However it should explain why it's slow even when > there are lots of free pages _globally_. > >> > >> >> complete ps output: >> >> http://pastebin.com/raw.php?i=b948svzN >> > >> > In that log, scp happens to be in R state and also no other tasks in D >> > state. Would you retry in the hope of catching some stucked state? >> Sadly not as the sysrq trigger has rebootet the machine and it will now run fine for 1 or 2 days. > > Oops, sorry! It might be possible to reproduce the issue by manually > eating all of the memory with sparse file data: > > truncate -s 1T 1T > cp 1T /dev/null > >> > >> >>> echo t> /proc/sysrq-trigger >> >> sadly i wa sonly able to grab the output in this crazy format: >> >> http://pastebin.com/raw.php?i=MBXvvyH1 >> > >> > It's pretty readable dmesg, except that the data is incomplete and >> > there are nothing valuable in the uploaded portion.. >> That was everything i could grab through netconsole. Is there a better way? > > netconsole is enough. The partial output should be due to the reboot... > > Thanks, > Fengguang > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@...ck.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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