From: Andrew Morton <akpm@linux-foundation.org>
To: "Theodore Ts'o" <tytso@mit.edu>,
Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
jack@suse.cz, Jens Axboe <jens.axboe@o
Subject: Re: [PATCH 1/3] block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks
Date: Mon, 6 Apr 2009 23:50:52 -0700 [thread overview]
Message-ID: <20090406235052.1ea47513.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090406232141.ebdb426a.akpm@linux-foundation.org>
On Mon, 6 Apr 2009 23:21:41 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> I mean, let's graph it:
>
> WRITE_SYNC -> WRITE_SYNC_PLUG -> BIO_RW_SYNCIO -> bio_sync() -> REQ_RW_SYNC -> rw_is_sync() -> does something mysterious in get_request()
> -> rq_is_sync() -> does something mysterious in IO schedulers
> -> BIO_RW_NOIDLE -> bio_noidle() -> REQ_NOIDLE -> rq_noidle() -> does something mysterious in cfq-iosched only
> -> BIO_RW_UNPLUG -> bio_unplug() -> REQ_UNPLUG -> OK, the cognoscenti know what this is supposed to do, but it is unused!
whoop, I found a use of bio_unplug() in __make_request().
So it appears that the intent of your patch is to cause an unplug after
submission of each WB_SYNC_ALL block?
But what about all the other stuff which WRITE_SYNC might or might not
do? What does WRITE_SYNC _actually_ do, and what are the actual
effects of this change??
And what effect will this large stream of unplugs have upon merging?
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Morton <akpm@linux-foundation.org>
To: "Theodore Ts'o" <tytso@mit.edu>,
Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
jack@suse.cz, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH 1/3] block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks
Date: Mon, 6 Apr 2009 23:50:52 -0700 [thread overview]
Message-ID: <20090406235052.1ea47513.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090406232141.ebdb426a.akpm@linux-foundation.org>
On Mon, 6 Apr 2009 23:21:41 -0700 Andrew Morton <akpm@linux-foundation.org> wrote:
> I mean, let's graph it:
>
> WRITE_SYNC -> WRITE_SYNC_PLUG -> BIO_RW_SYNCIO -> bio_sync() -> REQ_RW_SYNC -> rw_is_sync() -> does something mysterious in get_request()
> -> rq_is_sync() -> does something mysterious in IO schedulers
> -> BIO_RW_NOIDLE -> bio_noidle() -> REQ_NOIDLE -> rq_noidle() -> does something mysterious in cfq-iosched only
> -> BIO_RW_UNPLUG -> bio_unplug() -> REQ_UNPLUG -> OK, the cognoscenti know what this is supposed to do, but it is unused!
whoop, I found a use of bio_unplug() in __make_request().
So it appears that the intent of your patch is to cause an unplug after
submission of each WB_SYNC_ALL block?
But what about all the other stuff which WRITE_SYNC might or might not
do? What does WRITE_SYNC _actually_ do, and what are the actual
effects of this change??
And what effect will this large stream of unplugs have upon merging?
next prev parent reply other threads:[~2009-04-07 6:54 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-27 20:24 [PATCH 0/3] Ext3 latency improvement patches Theodore Ts'o
2009-03-27 20:24 ` [PATCH 1/3] block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks Theodore Ts'o
2009-03-27 20:24 ` [PATCH 2/3] ext3: Use WRITE_SYNC for commits which are caused by fsync() Theodore Ts'o
2009-03-27 20:24 ` [PATCH 3/3] ext3: Avoid starting a transaction in writepage when not necessary Theodore Ts'o
2009-03-27 22:23 ` Jan Kara
2009-03-27 23:03 ` Theodore Tso
2009-03-30 13:22 ` Jan Kara
2009-03-30 13:22 ` Jan Kara
2009-03-27 22:20 ` [PATCH 2/3] ext3: Use WRITE_SYNC for commits which are caused by fsync() Jan Kara
2009-03-27 20:55 ` [PATCH 1/3] block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks Jan Kara
2009-04-07 6:21 ` Andrew Morton
2009-04-07 6:50 ` Andrew Morton [this message]
2009-04-07 6:50 ` Andrew Morton
2009-04-07 7:08 ` Jens Axboe
2009-04-07 7:17 ` Jens Axboe
2009-04-07 8:16 ` Jens Axboe
2009-04-07 7:23 ` Andrew Morton
2009-04-07 7:57 ` Jens Axboe
2009-04-07 19:09 ` Theodore Tso
2009-04-07 19:32 ` Jens Axboe
2009-04-07 21:44 ` Theodore Tso
2009-04-07 22:19 ` [PATCH] block_write_full_page: switch synchronous writes to use WRITE_SYNC_PLUG Theodore Tso
2009-04-07 22:19 ` Theodore Tso
2009-04-07 23:09 ` Andrew Morton
2009-04-07 23:46 ` Theodore Tso
2009-04-08 8:08 ` Jens Axboe
2009-04-08 22:34 ` Andrew Morton
2009-04-09 17:59 ` Jens Axboe
2009-04-08 6:00 ` Jens Axboe
2009-04-08 15:26 ` Theodore Tso
2009-04-08 5:58 ` [PATCH 1/3] block_write_full_page: Use synchronous writes for WBC_SYNC_ALL writebacks Jens Axboe
2009-04-08 15:25 ` Theodore Tso
2009-04-07 14:19 ` Theodore Tso
2009-03-27 20:50 ` [PATCH 0/3] Ext3 latency improvement patches Chris Mason
2009-03-27 21:03 ` Chris Mason
2009-03-27 21:19 ` Jan Kara
2009-03-27 21:30 ` Theodore Tso
2009-03-27 21:54 ` Jan Kara
2009-03-27 21:54 ` Jan Kara
2009-03-27 23:09 ` Theodore Tso
2009-03-28 0:14 ` Jeff Garzik
2009-03-28 0:14 ` Jeff Garzik
2009-03-28 0:24 ` David Rees
2009-03-28 0:24 ` David Rees
2009-03-30 14:16 ` Ric Wheeler
2009-03-30 11:23 ` Aneesh Kumar K.V
2009-03-30 11:44 ` Chris Mason
2009-03-30 11:23 ` Aneesh Kumar K.V
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