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

Stefan Priebe - Profihost AG
2011-08-26T02:54:40Z

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