[dm-devel] patch to dm-emc.c
Edward Goggin
egoggin at emc.com
Tue Aug 29 20:57:10 UTC 2006
On Thursday, August 10, 2006 5:28 PM, Mike Christie wrote
> But I thought, a request should eventually complete and so we
> should be
> woken up from get_request_wait, and we will try allocate a
> request again
> and then the write request count should have gone down and we
> should be
> able to proceed.
Mike,
You are right. My logic was bad ... I was confusing mapped and
target device queues. Turns out the delays that I am seeing
(multipathd checker thread is stuck waiting for up to 15 minutes
waiting for a free target device queue) are due to ios being
held and timed out by the SCSI LLD (Emulex). I never waited
more than 10 minutes in my testing earlier in the month before
looking for some type of deadlock.
I've changed the patch to call blk_get_request() with __GFP_WAIT
always from a worker thread context since using pre-allocated
request structures does not help the problem.
Thanks,
Ed
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