From: Jens Axboe <axboe@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, kenneth.w.chen@intel.com,
thornber@redhat.com
Subject: Re: [PATCH] backing dev unplugging
Date: Wed, 10 Mar 2004 22:02:07 +0100 [thread overview]
Message-ID: <20040310210207.GL15087@suse.de> (raw)
In-Reply-To: <20040310130046.2df24f0e.akpm@osdl.org>
On Wed, Mar 10 2004, Andrew Morton wrote:
> Jens Axboe <axboe@suse.de> wrote:
> >
> > Here's a first cut at killing global plugging of block devices to reduce
> > the nasty contention blk_plug_lock caused.
>
> Shouldn't we take read_lock(&md->map_lock) in dm_table_unplug_all()?
Ugh yes, we certainly should.
> If so, what are the lock ranking issues here? The queue lock is not
> held yet, so it seems pretty simple?
As far as I can tell, it's pretty straight forward. The unplug_fn() will
grab the queue lock for 'ordinary' devices, for dm on dm you'd nest the
maplock inside each other (which should be quite alright, as far as I
can tell, without pulling any nasty tricks).
--
Jens Axboe
next prev parent reply other threads:[~2004-03-10 21:04 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-10 12:45 [PATCH] backing dev unplugging Jens Axboe
2004-03-10 19:55 ` Andrew Morton
2004-03-10 20:03 ` Kenneth Chen
2004-03-10 20:20 ` Jens Axboe
2004-03-10 20:45 ` Jesse Barnes
2004-03-10 20:49 ` Jens Axboe
[not found] ` <20040310205237.GK15087@suse.de>
2004-03-10 21:01 ` Jesse Barnes
2004-03-10 21:02 ` Jens Axboe
2004-03-10 21:35 ` Jesse Barnes
2004-03-10 23:54 ` Andrew Morton
2004-03-11 0:03 ` David Mosberger
2004-03-11 6:30 ` Jesse Barnes
2004-03-10 20:17 ` Jens Axboe
2004-03-15 5:53 ` Kenneth Chen
2004-03-10 20:14 ` Jeff Garzik
2004-03-10 20:19 ` Jens Axboe
2004-03-10 21:00 ` Andrew Morton
2004-03-10 21:02 ` Jens Axboe [this message]
2004-03-10 21:40 ` Miquel van Smoorenburg
2004-03-10 23:05 ` Andrew Morton
2004-03-11 0:05 ` Miquel van Smoorenburg
2004-03-11 0:17 ` Andrew Morton
2004-03-11 6:43 ` Jens Axboe
2004-03-10 22:22 ` Nathan Scott
2004-03-10 23:32 ` Steve Lord
2004-03-11 7:05 ` Jens Axboe
2004-03-11 9:14 ` Joe Thornber
2004-03-11 9:16 ` Jens Axboe
2004-03-11 12:17 ` Christophe Saout
2004-03-11 12:22 ` Jens Axboe
2004-03-11 13:11 ` Christophe Saout
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