From: Shaohua Li <shli@kernel.org>
To: NeilBrown <neilb@suse.de>
Cc: linux-raid@vger.kernel.org, axboe@kernel.dk,
dan.j.williams@intel.com, shli@fusionio.com
Subject: Re: [patch 01/10 v3] raid5: use wake_up_all for overlap waking
Date: Thu, 28 Jun 2012 16:53:09 +0800 [thread overview]
Message-ID: <20120628085309.GA8024@kernel.org> (raw)
In-Reply-To: <20120628172621.463d9a84@notabene.brown>
On Thu, Jun 28, 2012 at 05:26:21PM +1000, NeilBrown wrote:
> On Mon, 25 Jun 2012 15:24:48 +0800 Shaohua Li <shli@kernel.org> wrote:
>
> > It's possible several tasks are waiting for stripe overlap. We clear R5_Overlap
> > bit and wake_up, but wake_up just wakes one task. So if there are several tasks
> > in the wait queue, some tasks will not be woken up even its strip R5_Overlap
> > clear. The end result is tasks hang in make_request.
> >
> > wake_up_all should not introduce performance issue here, since overlap case is
> > rare.
>
> This is not necessary.
> wake_up_all is only different from wake_up if WQ_FLAG_EXCLUSIVE it set, e.g.
> by prepare_to_wait_exclusive.
> As we don't use an exclusive wait to wait on wait_for_overlap, there is no
> point in using wake_up_all, wake_up already wakes everything up.
Oh, this is silly, sorry about it. So the only problem I hit the hang is that I
fixed in the second patch. Other patches can still applied without this one.
Thanks,
Shaohua
next prev parent reply other threads:[~2012-06-28 8:53 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-25 7:24 [patch 00/10 v3] raid5: improve write performance for fast storage Shaohua Li
2012-06-25 7:24 ` [patch 01/10 v3] raid5: use wake_up_all for overlap waking Shaohua Li
2012-06-28 7:26 ` NeilBrown
2012-06-28 8:53 ` Shaohua Li [this message]
2012-06-25 7:24 ` [patch 02/10 v3] raid5: delayed stripe fix Shaohua Li
2012-07-02 0:46 ` NeilBrown
2012-07-02 0:49 ` Shaohua Li
2012-07-02 0:55 ` NeilBrown
2012-06-25 7:24 ` [patch 03/10 v3] raid5: add a per-stripe lock Shaohua Li
2012-07-02 0:50 ` NeilBrown
2012-07-02 3:16 ` Shaohua Li
2012-07-02 7:39 ` NeilBrown
2012-07-03 1:27 ` Shaohua Li
2012-07-03 12:16 ` majianpeng
2012-07-03 23:56 ` NeilBrown
2012-07-04 1:09 ` majianpeng
2012-06-25 7:24 ` [patch 04/10 v3] raid5: lockless access raid5 overrided bi_phys_segments Shaohua Li
2012-06-25 7:24 ` [patch 05/10 v3] raid5: remove some device_lock locking places Shaohua Li
2012-06-25 7:24 ` [patch 06/10 v3] raid5: reduce chance release_stripe() taking device_lock Shaohua Li
2012-07-02 0:57 ` NeilBrown
2012-06-25 7:24 ` [patch 07/10 v3] md: personality can provide unplug private data Shaohua Li
2012-07-02 1:06 ` NeilBrown
2012-06-25 7:24 ` [patch 08/10 v3] raid5: make_request use batch stripe release Shaohua Li
2012-07-02 2:31 ` NeilBrown
2012-07-02 2:59 ` Shaohua Li
2012-07-02 5:07 ` NeilBrown
2012-06-25 7:24 ` [patch 09/10 v3] raid5: raid5d handle stripe in batch way Shaohua Li
2012-07-02 2:32 ` NeilBrown
2012-06-25 7:24 ` [patch 10/10 v3] raid5: create multiple threads to handle stripes Shaohua Li
2012-07-02 2:39 ` NeilBrown
2012-07-02 20:03 ` Dan Williams
2012-07-03 8:04 ` Shaohua Li
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