Subject: Re: slow performance on disk/network i/o full speed after drop_caches

From: Stefan Priebe - Profihost AG <[email-masked]>
Date: Thu, 25 Aug 2011 11:00:26 +0200

Am 24.08.2011 11:33, schrieb Wu Fengguang:
> On Wed, Aug 24, 2011 at 05:01:03PM +0800, Stefan Priebe - Profihost AG wrote:
>>
>>>> sync&&   echo 3>/proc/sys/vm/drop_caches&&   sleep 2&&   echo 0
>>>>> /proc/sys/vm/drop_caches
>>
>> Another way to get it working again is to stop some processes. Could be
>> mysql or apache or php fcgi doesn't matter. Just free some memory.
>> Although there are already 5GB free.
>
> Is it a NUMA machine and _every_ node has enough free pages?
>
>          grep . /sys/devices/system/node/node*/vmstat
>
> Thanks,
> Fengguang
Hi Fengguang,

thanks for your fast reply.

Here is the data you requested:

root@server1015-han:~# grep . /sys/devices/system/node/node*/vmstat
/sys/devices/system/node/node0/vmstat:nr_written 5546561
/sys/devices/system/node/node0/vmstat:nr_dirtied 5572497
/sys/devices/system/node/node1/vmstat:nr_written 3936
/sys/devices/system/node/node1/vmstat:nr_dirtied 4190

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/
root     12409 12409 TS       -   0  19   0 64.0  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   0 67.7  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   8 70.6  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   8 73.5  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   8 76.0  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   8 78.2  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   8 80.0  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   8 80.9  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   2 76.7  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 75.6  42136  1724  0.0 Ds 
pipe_read                    scp -t /tmp/
root     12409 12409 TS       -   0  19   0 76.0  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   1 75.2  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   1 76.6  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   1 77.9  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   1 79.0  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 72.8  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   0 73.0  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   0 73.8  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 74.3  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 73.4  42136  1724  0.0 Ss 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   1 71.3  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 71.9  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   0 72.7  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   3 73.5  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   3 74.4  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   3 75.2  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   0 76.0  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   8 76.6  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 74.8  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 73.2  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   1 73.9  42136  1724  0.0 Rs 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   0 72.4  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   8 72.0  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   8 72.5  42136  1724  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12409 12409 TS       -   0  19   8 72.9  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12409 12409 TS       -   0  19   8 73.5  42136  1724  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1  0.0  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 23.0  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 49.5  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   2 63.3  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 71.5  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 77.4  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 70.3  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 73.1  42136  1728  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12566 12566 TS       -   0  19   0 65.7  42136  1728  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/
root     12566 12566 TS       -   0  19   1 61.2  42136  1728  0.0 Ss 
-                            scp -t /tmp/
root     12566 12566 TS       -   0  19   1 63.7  42136  1728  0.0 Rs 
-                            scp -t /tmp/
root     12636 12636 TS       -   0  19   8  0.0  42136  1728  0.0 Ss 
poll_schedule_timeout        scp -t /tmp/

Stefan

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