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From: Jeff Garzik <jeff@garzik.org>
To: Theodore Tso <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
	Chris Mason <chris.mason@oracle.com>,
	Ric Wheeler <rwheeler@redhat.com>,
	Linux Kernel Developers List <linux-kernel@vger.kernel.
Subject: Re: [PATCH 0/3] Ext3 latency improvement patches
Date: Fri, 27 Mar 2009 20:14:04 -0400	[thread overview]
Message-ID: <49CD6BCC.6080602@garzik.org> (raw)
In-Reply-To: <20090327230902.GG5176@mit.edu>

Theodore Tso wrote:
> OTOH, the really big databases will tend to use direct I/O, so they
> won't be dirtying the page cache anyway.  So maybe it's not worth the

Not necessarily...  From what I understand, a lot of the individual 
low-level components in cloud storage, such as GoogleFS's chunk 
server[1] do not bypass the page cache, even though they do care about 
the details of data caching and data consistency.

I am looking at the same areas for my own distributed storage work, and 
am finding that the current crop of Linux-specific, 
database/server-friendly syscalls permit more application control over 
pagecache usage than in past years, decreasing the need for O_DIRECT. 
Things like readahead(2), sync_file_range(2), fadvise(3), really help.

	Jeff


[1] http://labs.google.com/papers/gfs-sosp2003.pdf


WARNING: multiple messages have this Message-ID (diff)
From: Jeff Garzik <jeff@garzik.org>
To: Theodore Tso <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
	Chris Mason <chris.mason@oracle.com>,
	Ric Wheeler <rwheeler@redhat.com>,
	Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
	Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH 0/3] Ext3 latency improvement patches
Date: Fri, 27 Mar 2009 20:14:04 -0400	[thread overview]
Message-ID: <49CD6BCC.6080602@garzik.org> (raw)
In-Reply-To: <20090327230902.GG5176@mit.edu>

Theodore Tso wrote:
> OTOH, the really big databases will tend to use direct I/O, so they
> won't be dirtying the page cache anyway.  So maybe it's not worth the

Not necessarily...  From what I understand, a lot of the individual 
low-level components in cloud storage, such as GoogleFS's chunk 
server[1] do not bypass the page cache, even though they do care about 
the details of data caching and data consistency.

I am looking at the same areas for my own distributed storage work, and 
am finding that the current crop of Linux-specific, 
database/server-friendly syscalls permit more application control over 
pagecache usage than in past years, decreasing the need for O_DIRECT. 
Things like readahead(2), sync_file_range(2), fadvise(3), really help.

	Jeff


[1] http://labs.google.com/papers/gfs-sosp2003.pdf


  reply	other threads:[~2009-03-28  0:14 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
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 [this message]
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 11:23       ` Aneesh Kumar K.V
2009-03-30 11:44         ` Chris Mason

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