Just for the record. 2.11.0 has fixed this. Not sure which LU though.

Cheers,
Hans Henrik

On 30-09-2017 23:43, Hans Henrik Happe wrote:
On 27-09-2017 18:50, Dilger, Andreas wrote:
On Sep 26, 2017, at 01:10, Hans Henrik Happe<ha...@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.
I've attached the stacks. Some wakeup which I guess are initiated by something in the ptlrpc code.

Cheers,
Hans Henrik




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