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

Stefan Priebe - Profihost AG
2011-08-25T09:00:31Z

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