Messages in this thread | | | From | Jeff Moyer <> | Subject | Re: [PATCH V2] writeback: fix hung_task alarm when sync block | Date | Wed, 13 Jun 2012 10:27:50 -0400 |
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Wanpeng Li <liwp.linux@gmail.com> writes:
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c > index f2d0109..df879ee 100644 > --- a/fs/fs-writeback.c > +++ b/fs/fs-writeback.c > @@ -1311,7 +1311,11 @@ void writeback_inodes_sb_nr(struct super_block *sb, > > WARN_ON(!rwsem_is_locked(&sb->s_umount)); > bdi_queue_work(sb->s_bdi, &work); > - wait_for_completion(&done); > + if (sysctl_hung_task_timeout_secs) > + while (!wait_for_completion_timeout(&done, HZ/2)) > + ; > + else > + wait_for_completion(&done); > } > EXPORT_SYMBOL(writeback_inodes_sb_nr);
Is it really expected that writeback_inodes_sb_nr will routinely queue up more than 2 seconds worth of I/O (Yes, I understand that it isn't the only entity issuing I/O)? For devices that are really slow, it may make more sense to tune the system so that you don't have too much writeback I/O submitted at once. Dropping nr_requests for the given queue should fix this situation, I would think.
This really feels like we're papering over the problem.
Cheers, Jeff
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