[libvirt] Is it a workqueue related issue in 2.6.37 (Was: Re: blkio cgroup [solved])

[Dominik Klein]

> Maybe watching what the workqueue is doing using the following trace
> events could be helpful.
> 
> # grep workqueue /sys/kernel/debug/tracing/available_events
> workqueue:workqueue_insertion
> workqueue:workqueue_execution
> workqueue:workqueue_creation
> workqueue:workqueue_destruction

Since I've never done this before, I will tell you how I captured the
trace so you know what I did and can see whether I did something wrong
and can correct me if necessary.

echo blk > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/block/sdb/trace/enable
echo workqueue_queue_work >> /sys/kernel/debug/tracing/set_event
echo workqueue_activate_work >> /sys/kernel/debug/tracing/set_event
echo workqueue_execute_start >> /sys/kernel/debug/tracing/set_event
echo workqueue_execute_end >> /sys/kernel/debug/tracing/set_event
cat /sys/kernel/debug/tracing/trace_pipe

And that output i gzip'd.

This was taken with 2.6.37 plus the patch you mentioned on a Dell R815
with 2 12 core AMD Opteron 6174 CPUs. If you need any more information,
please let me know.

Regards
Dominik
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