Re: Hung task - sync - 2.6.33-rc7 w/md6 multicore rebuild in process

From: Michael Breuer
Date: Wed Feb 17 2010 - 21:52:13 EST


On 2/17/2010 9:39 PM, Jan Kara wrote:
On 2/13/2010 11:51 AM, Michael Breuer wrote:
Note: this cleared after about 90 minutes - sync eventually completed.
I'm thinking that with multicore enabled the resync is able to starve
out normal system activities that weren't starved w/o multicore.
Hmm, it is a bug in writeback code. But as Linus pointed out, it's not really
clear why it's *so* slow. So when it happens again, could you please sample for
a while (like every second for 30 seconds) stacks of blocked tasks via
Alt-Sysrq-W? I'd like to see where flusher threads are hanging... Thanks.

Honza
Ok - will do. On rc8 now - and up about 3 days without any issues. If I have some time tomorrow I'll force a raid resync and see what happens.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/