From: Jens Axboe <jaxboe@fusionio.com>
To: "hch@infradead.org" <hch@infradead.org>
Cc: Vivek Goyal <vgoyal@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 07/10] fs: make generic file read/write functions plug
Date: Fri, 4 Mar 2011 23:07:51 +0100 [thread overview]
Message-ID: <4D7162B7.20101@fusionio.com> (raw)
In-Reply-To: <20110304140814.GA28953@infradead.org>
On 2011-03-04 15:08, hch@infradead.org wrote:
> On Fri, Mar 04, 2011 at 02:40:09PM +0100, Jens Axboe wrote:
>>> REQ_META? Maybe we should finally agree what it does and decide if it
>>> should be used consistenly. Especially the priority over REQ_SYNC in
>>> cfq still looks somewhat odd, as does the totally inconsequent use.
>>
>> For me it was primarily a blktrace hint, but yes it does have prio boost
>> properties in CFQ as well. I'm inclined to let those stay the way they
>> are. Not sure we can properly call it anything outside of a hint that
>> these IO have slightly higher priority, at least I would not want to
>> lock the IO scheduler into to something more concrete than that.
>
> The problem is that these two meanings are inherently conflicting.
> Metadata updates do not have to be synchronous or have any kind of
> priority. In fact for XFS they normall aren't, and I'd be surprised it
> the same isn't true for other journalled filesystems.
>
> Priority metadata goes into the log, which for XFS is always written as
> a FLUSH+FUA bio. Writeback of metadata happens asynchronously in the
> background, and only becomes a priority if the journal is full and we'll
> need to make space available.
>
> So giving plain REQ_META a priority boost makes it impossible to use it
> for the blktrace annotation use case. One could only apply the boost
> for the REQ_SYNC + REQ_META combination, but even that seems rather
> hackish to me. I'd really love to see numbers where the additional
> boost of REQ_META over REQ_SYNC makes any difference.
Seems only gfs2 actually sets the flag now. So how about we remove the
prio boost for meta data and just retain it as an information attribute?
If there's a need for this slight boosts, it is probably best done
explicitly being signalled from the caller.
--
Jens Axboe
next prev parent reply other threads:[~2011-03-04 22:07 UTC|newest]
Thread overview: 152+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-22 1:17 [PATCH 0/10] On-stack explicit block queue plugging Jens Axboe
2011-01-22 1:17 ` [PATCH 01/10] block: add API for delaying work/request_fn a little bit Jens Axboe
2011-01-22 1:17 ` [PATCH 02/10] ide-cd: convert to blk_delay_queue() for a short pause Jens Axboe
2011-01-22 1:19 ` David Miller
2011-01-22 1:17 ` [PATCH 03/10] scsi: convert to blk_delay_queue() Jens Axboe
2011-01-22 1:17 ` [PATCH 04/10] block: initial patch for on-stack per-task plugging Jens Axboe
2011-01-24 19:36 ` Jeff Moyer
2011-01-24 21:23 ` Jens Axboe
2011-03-10 16:54 ` Vivek Goyal
2011-03-10 19:32 ` Jens Axboe
2011-03-10 19:46 ` Vivek Goyal
2011-03-16 8:18 ` Shaohua Li
2011-03-16 17:31 ` Vivek Goyal
2011-03-17 1:00 ` Shaohua Li
2011-03-17 3:19 ` Shaohua Li
2011-03-17 9:44 ` Jens Axboe
2011-03-18 1:55 ` Shaohua Li
2011-03-17 9:43 ` Jens Axboe
2011-03-18 6:36 ` Shaohua Li
2011-03-18 12:54 ` Jens Axboe
2011-03-18 13:52 ` Jens Axboe
2011-03-21 6:52 ` Shaohua Li
2011-03-21 9:20 ` Jens Axboe
2011-03-22 0:32 ` Shaohua Li
2011-03-22 7:36 ` Jens Axboe
2011-03-17 9:39 ` Jens Axboe
2011-01-22 1:17 ` [PATCH 05/10] block: remove per-queue plugging Jens Axboe
2011-01-22 1:31 ` Nick Piggin
2011-03-03 21:23 ` Mike Snitzer
2011-03-03 21:27 ` Mike Snitzer
2011-03-03 22:13 ` Mike Snitzer
2011-03-04 13:02 ` Shaohua Li
2011-03-04 13:20 ` Jens Axboe
2011-03-04 21:43 ` Mike Snitzer
2011-03-04 21:50 ` Jens Axboe
2011-03-04 22:27 ` Mike Snitzer
2011-03-05 20:54 ` Jens Axboe
2011-03-07 10:23 ` Peter Zijlstra
2011-03-07 19:43 ` Jens Axboe
2011-03-07 20:41 ` Peter Zijlstra
2011-03-07 20:46 ` Jens Axboe
2011-03-08 9:38 ` Peter Zijlstra
2011-03-08 9:41 ` Jens Axboe
2011-03-07 0:54 ` Shaohua Li
2011-03-07 8:07 ` Jens Axboe
2011-03-08 12:16 ` Jens Axboe
2011-03-08 20:21 ` Mike Snitzer
2011-03-08 20:27 ` Jens Axboe
2011-03-08 21:36 ` Jeff Moyer
2011-03-09 7:25 ` Jens Axboe
2011-03-08 22:05 ` Mike Snitzer
2011-03-10 0:58 ` Mike Snitzer
2011-04-05 3:05 ` NeilBrown
2011-04-11 4:50 ` NeilBrown
2011-04-11 9:19 ` Jens Axboe
2011-04-11 10:59 ` NeilBrown
2011-04-11 11:04 ` Jens Axboe
2011-04-11 11:26 ` NeilBrown
2011-04-11 11:37 ` Jens Axboe
2011-04-11 12:05 ` NeilBrown
2011-04-11 12:11 ` Jens Axboe
2011-04-11 12:36 ` NeilBrown
2011-04-11 12:48 ` Jens Axboe
2011-04-12 1:12 ` hch
2011-04-12 8:36 ` Jens Axboe
2011-04-12 12:22 ` Dave Chinner
2011-04-12 12:28 ` Jens Axboe
2011-04-12 12:41 ` Dave Chinner
2011-04-12 12:58 ` Jens Axboe
2011-04-12 13:31 ` Dave Chinner
2011-04-12 13:45 ` Jens Axboe
2011-04-12 14:34 ` Dave Chinner
2011-04-12 21:08 ` NeilBrown
2011-04-13 2:23 ` Linus Torvalds
2011-04-13 11:12 ` Peter Zijlstra
2011-04-13 11:23 ` Jens Axboe
2011-04-13 11:41 ` Peter Zijlstra
2011-04-13 15:13 ` Linus Torvalds
2011-04-13 17:35 ` Jens Axboe
2011-04-12 16:58 ` hch
2011-04-12 17:29 ` Jens Axboe
2011-04-12 16:44 ` hch
2011-04-12 16:49 ` Jens Axboe
2011-04-12 16:54 ` hch
2011-04-12 17:24 ` Jens Axboe
2011-04-12 13:40 ` Dave Chinner
2011-04-12 13:48 ` Jens Axboe
2011-04-12 23:35 ` Dave Chinner
2011-04-12 16:50 ` hch
2011-04-15 4:26 ` hch
2011-04-15 6:34 ` Jens Axboe
2011-04-17 22:19 ` NeilBrown
2011-04-18 4:19 ` NeilBrown
2011-04-18 6:38 ` Jens Axboe
2011-04-18 7:25 ` NeilBrown
2011-04-18 8:10 ` Jens Axboe
2011-04-18 8:33 ` NeilBrown
2011-04-18 8:42 ` Jens Axboe
2011-04-18 21:23 ` hch
2011-04-22 15:39 ` hch
2011-04-22 16:01 ` Vivek Goyal
2011-04-22 16:10 ` Vivek Goyal
2011-04-18 21:30 ` hch
2011-04-18 22:38 ` NeilBrown
2011-04-20 10:55 ` hch
2011-04-18 9:19 ` hch
2011-04-18 9:40 ` [dm-devel] " Hannes Reinecke
2011-04-18 9:47 ` Jens Axboe
2011-04-18 9:46 ` Jens Axboe
2011-04-11 11:55 ` NeilBrown
2011-04-11 12:12 ` Jens Axboe
2011-04-11 22:58 ` hch
2011-04-12 6:20 ` Jens Axboe
2011-04-11 16:59 ` hch
2011-04-11 21:14 ` NeilBrown
2011-04-11 22:59 ` hch
2011-04-12 6:18 ` Jens Axboe
2011-03-17 15:51 ` Mike Snitzer
2011-03-17 18:31 ` Jens Axboe
2011-03-17 18:46 ` Mike Snitzer
2011-03-18 9:15 ` hch
2011-03-08 12:15 ` Jens Axboe
2011-03-04 4:00 ` Vivek Goyal
2011-03-08 12:24 ` Jens Axboe
2011-03-08 22:10 ` blk-throttle: Use blk_plug in throttle code (Was: Re: [PATCH 05/10] block: remove per-queue plugging) Vivek Goyal
2011-03-09 7:26 ` Jens Axboe
2011-01-22 1:17 ` [PATCH 06/10] block: kill request allocation batching Jens Axboe
2011-01-22 9:31 ` Christoph Hellwig
2011-01-24 19:09 ` Jens Axboe
2011-01-22 1:17 ` [PATCH 07/10] fs: make generic file read/write functions plug Jens Axboe
2011-01-24 3:57 ` Dave Chinner
2011-01-24 19:11 ` Jens Axboe
2011-03-04 4:09 ` Vivek Goyal
2011-03-04 13:22 ` Jens Axboe
2011-03-04 13:25 ` hch
2011-03-04 13:40 ` Jens Axboe
2011-03-04 14:08 ` hch
2011-03-04 22:07 ` Jens Axboe [this message]
2011-03-04 23:12 ` hch
2011-03-08 12:38 ` Jens Axboe
2011-03-09 10:38 ` hch
2011-03-09 10:52 ` Jens Axboe
2011-01-22 1:17 ` [PATCH 08/10] read-ahead: use plugging Jens Axboe
2011-01-22 1:17 ` [PATCH 09/10] fs: make mpage read/write_pages() plug Jens Axboe
2011-01-22 1:17 ` [PATCH 10/10] fs: make aio plug Jens Axboe
2011-01-24 17:59 ` Jeff Moyer
2011-01-24 19:09 ` Jens Axboe
2011-01-24 19:15 ` Jeff Moyer
2011-01-24 19:22 ` Jens Axboe
2011-01-24 19:29 ` Jeff Moyer
2011-01-24 19:31 ` Jens Axboe
2011-01-24 19:38 ` Jeff Moyer
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