From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Theodore Ts'o" <tytso@mit.edu>, Jens Axboe <jens.axboe@oracle.com>
Cc: Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: [GIT PULL] Ext3 latency fixes
Date: Fri, 3 Apr 2009 11:24:50 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.00.0904031110420.19690@localhost.localdomain> (raw)
In-Reply-To: <1238742067-30814-1-git-send-email-tytso@mit.edu>
On Fri, 3 Apr 2009, Theodore Ts'o wrote:
>
> Please pull from:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4.git ext3-latency-fixes
Thanks, pulled. I'll be interested to see how it feels. Will report back
after I've rebuild and gone through a few more emails.
One thing I started wondering about in your changes to start using
WRITE_SYNC is that I'm getting closer to thinking that we did the whole
WRITE-vs-WRITE_SYNC thing the wrong way around.
Now, it's clearly true that non-synchronous writes are hopefully always
the common case, so in that sense it makes sense to think of "WRITE" as
the default non-critical case, and then make the (fewer) WRITE_SYNC cases
be the special case.
But at the same time, I now suspect that we could actually have solved
this problem more easily by just doing things the other way around: make
the default "WRITE" be the high-priority one (to match "READ"), and then
just explicitly marking the data writes with "WRITE_ASYNC".
Why? Because I think that with all the writes sprinkled around in random
places, it's probably _easier_ to find the bulk writes that cause the
biggest issues, and just fix _those_ to be WRITE_ASYNC. They may be bulk,
they may be the common case, but they also tend to be the case where we
write with generic routines (eg the whole "do_writepages()" thing).
So the VFS layer tends to already do much of the bulk writeout, and maybe
we would have been better off just changing those to ASYNC and leaving any
more specialized cases as the SYNC case? That would have avoided a lot of
this effort at the filesystem level. We'd just assume that the default
filesystem-specific writes tend to all be SYNC.
Comments?
Linus
next prev parent reply other threads:[~2009-04-03 18:27 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-03 7:01 [GIT PULL] Ext3 latency fixes Theodore Ts'o
2009-04-03 7:01 ` [PATCH 1/4] block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks Theodore Ts'o
2009-04-03 7:01 ` [PATCH 2/4] ext3: Use WRITE_SYNC for commits which are caused by fsync() Theodore Ts'o
2009-04-03 7:01 ` [PATCH 3/4] ext3: Add replace-on-truncate hueristics for data=writeback mode Theodore Ts'o
2009-04-03 7:01 ` [PATCH 4/4] ext3: Add replace-on-rename " Theodore Ts'o
2009-04-03 18:24 ` Linus Torvalds [this message]
2009-04-03 18:47 ` [GIT PULL] Ext3 latency fixes Jens Axboe
2009-04-03 19:13 ` Theodore Tso
2009-04-03 21:01 ` Chris Mason
2009-04-03 19:02 ` Linus Torvalds
2009-04-03 20:41 ` Linus Torvalds
2009-04-04 13:57 ` Theodore Tso
2009-04-04 15:16 ` Jens Axboe
2009-04-04 15:57 ` Linus Torvalds
2009-04-04 16:06 ` Linus Torvalds
2009-04-04 17:36 ` Jens Axboe
2009-04-04 17:34 ` Jens Axboe
2009-04-04 17:44 ` Linus Torvalds
2009-04-04 18:00 ` Trenton D. Adams
2009-04-04 18:01 ` Jens Axboe
2009-04-04 18:10 ` Linus Torvalds
2009-04-04 23:22 ` Theodore Tso
2009-04-04 23:33 ` Arjan van de Ven
2009-04-05 0:10 ` Theodore Tso
2009-04-05 15:05 ` Arjan van de Ven
2009-04-05 17:01 ` Linus Torvalds
2009-04-05 17:15 ` Mark Lord
2009-04-05 20:57 ` Jeff Garzik
2009-04-05 23:48 ` Arjan van de Ven
2009-04-06 2:32 ` Mark Lord
2009-04-06 5:47 ` Jeff Garzik
2009-04-07 18:18 ` Linus Torvalds
2009-04-07 18:22 ` Linus Torvalds
2009-04-07 19:40 ` [PATCH libata: add SSD detection hueristic; move SSD setup to ata_dev_configure (was Re: [GIT PULL] Ext3 latency fixes) Jeff Garzik
2009-04-09 18:21 ` Tejun Heo
2009-04-18 3:02 ` George Spelvin
2009-04-06 8:13 ` [GIT PULL] Ext3 latency fixes Jens Axboe
2009-04-05 18:56 ` Arjan van de Ven
2009-04-05 19:34 ` Linus Torvalds
2009-04-05 20:06 ` Arjan van de Ven
2009-04-06 6:25 ` Jens Axboe
2009-04-06 6:05 ` Theodore Tso
2009-04-06 6:23 ` Jens Axboe
2009-04-06 8:16 ` Jens Axboe
2009-04-06 14:48 ` Linus Torvalds
2009-04-06 15:09 ` Jens Axboe
2009-04-06 6:15 ` Jens Axboe
2009-04-04 20:18 ` Ingo Molnar
2009-04-06 21:50 ` Lennart Sorensen
2009-04-07 13:31 ` Mark Lord
2009-04-07 14:48 ` Lennart Sorensen
2009-04-07 19:21 ` Mark Lord
2009-04-07 19:57 ` Lennart Sorensen
2009-04-04 20:56 ` Arjan van de Ven
2009-04-06 7:06 ` Jens Axboe
2009-04-07 15:39 ` Indan Zupancic
2009-04-04 19:18 ` Theodore Tso
2009-04-06 8:12 ` Jens Axboe
2009-04-04 22:13 ` Linus Torvalds
2009-04-04 22:19 ` Linus Torvalds
2009-04-05 0:20 ` Theodore Tso
2009-04-03 19:54 ` Theodore Tso
2009-04-08 23:40 Theodore Ts'o
2009-04-09 15:49 ` Linus Torvalds
2009-04-09 16:23 ` Chris Mason
2009-04-09 17:49 ` Jan Kara
2009-04-09 18:10 ` Chris Mason
2009-04-09 19:04 ` Jan Kara
2009-04-09 17:36 ` Jan Kara
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