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

Wu Fengguang
2011-08-26T03:03:18Z

On Fri, Aug 26, 2011 at 10:54:35AM +0800, Stefan Priebe - Profihost AG wrote:
> 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.

Thanks. This shows that node0 is accessed 10x more than node1.

> 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

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?

> > 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..

Thanks,
Fengguang