[lustre-discuss] 2.10.0 CentOS6.9 ksoftirqd CPU load

[Dilger, Andreas]

On Sep 26, 2017, at 01:10, Hans Henrik Happe <happe at nbi.dk> wrote:
> 
> Hi,
> 
> Did anyone else experience CPU load from ksoftirqd after 'modprobe
> lustre'? On an otherwise idle node I see:
> 
>  PID USER      PR   NI VIRT  RES  SHR S %CPU  %MEM TIME+   COMMAND
>    9 root      20   0     0    0    0 S 28.5  0.0  2:05.58 ksoftirqd/1
> 
> 
>   57 root      20   0     0    0    0 R 23.9  0.0  2:22.91 ksoftirqd/13
> 
> The sum of those two is about 50% CPU.
> 
> I have narrowed it down to the ptlrpc module. When I remove that, it stops.
> 
> I also tested the 2.10.1-RC1, which is the same.

If you can run "echo l > /proc/sysrq-trigger" it will report the processes
that are currently running on the CPUs of your system to the console (and
also /var/log/messages, if it can write everything in time).

You might need to do this several times to get a representative sample of
the ksoftirqd process stacks to see what they are doing that is consuming
so much CPU.

Alternately, "echo t > /proc/sysrq-trigger" will report the stacks of all
processes to the console (and /v/l/m), but there will be a lot of them,
and no better chance that it catches what ksoftirqd is doing 25% of the time.

Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Intel Corporation