linux-kernel - Re: slow performance on disk/network i/o full speed after drop

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Message-ID: <4E570AEB.1040703@profihost.ag>
Date:	Fri, 26 Aug 2011 04:54:35 +0200
From:	Stefan Priebe - Profihost AG <s.priebe@...fihost.ag>
To:	Wu Fengguang <fengguang.wu@...el.com>
CC:	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

Hi Wu,

> Ah you are running an older kernel that didn't show all the vmstat
> numbers. But still it's revealing that node 0 is used heavily and node
> 1 is almost idle. So I won't be surprised to see most free pages lie
> in node 1.
I'm running a 2.6.38 kernel.

There is at least a numastat proc file.
grep . /sys/devices/system/node/node*/numastat
/sys/devices/system/node/node0/numastat:numa_hit 5958586
/sys/devices/system/node/node0/numastat:numa_miss 0
/sys/devices/system/node/node0/numastat:numa_foreign 0
/sys/devices/system/node/node0/numastat:interleave_hit 4191
/sys/devices/system/node/node0/numastat:local_node 5885189
/sys/devices/system/node/node0/numastat:other_node 73397
/sys/devices/system/node/node1/numastat:numa_hit 488922
/sys/devices/system/node/node1/numastat:numa_miss 0
/sys/devices/system/node/node1/numastat:numa_foreign 0
/sys/devices/system/node/node1/numastat:interleave_hit 4187
/sys/devices/system/node/node1/numastat:local_node 386741
/sys/devices/system/node/node1/numastat:other_node 102181

>> modified it a little bit:
>> ~# while [ true ]; do ps -eo
>> user,pid,tid,class,rtprio,ni,pri,psr,pcpu,vsz,rss,pmem,stat,wchan:28,cmd
>> | grep scp | grep -v grep; sleep 1; done
>>
>> root     12409 12409 TS       -   0  19   0 59.8  42136  1724  0.0 Ss
>> poll_schedule_timeout        scp -t /tmp/
>
> It's mostly doing poll() waits. There must be some dependency on
> something other to make progress. Would you post the full ps output
> for all tasks, and even better, run
complete ps output:
http://pastebin.com/raw.php?i=b948svzN

>          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

Hope that still helps.

Thanks Stefan
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