Am 25.06.2012 20:02, schrieb Josef Bacik:

quoted

  >  Can you turn that off and see if you

quoted

can still reproduce the deadlock?  If so sysrq+w again, if not then I know where
to look ;).  Thanks,

without discard i can't reproduce but random write speed with ceph
without discard is a LOT slower (around 8000 iops/s instead of
13000iops/s). So i don't know if it is discard or if i'm just not able
to trigger it.

Ouch, what kind of drive goes faster with discard _on_?  Anyway it looks like
we're waiting for the discard to come back, so either its your drive or theres a
bug in the block layer.  Maybe try an older kernel and see if it's broken there,
and then bisect it down?  Thanks,

Intel 520 series SSD. I can't try an older kernel version as ceph 
crashes with them pretty fast due to other bugs which where fixed with 
3.5-rc1.

Greets
Stefan