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From: Jens Axboe <axboe@suse.de>
To: Hans Reiser <reiser@namesys.com>
Cc: Tom Vier <tmv@comcast.net>,
	Linux-Kernel@vger.kernel.org,
	Reiserfs developers mail-list <Reiserfs-Dev@namesys.com>,
	Reiserfs mail-list <Reiserfs-List@namesys.com>
Subject: Re: [PATCH] updated reiser4 - reduced cpu usage for writes by writing  more than 4k at a time (has implications for generic write code and eventually  for the IO layer)
Date: Thu, 8 Jun 2006 13:00:45 +0200	[thread overview]
Message-ID: <20060608110044.GA5207@suse.de> (raw)
In-Reply-To: <44749E24.40203@namesys.com>

On Wed, May 24 2006, Hans Reiser wrote:
> Tom Vier wrote:
> 
> >On Tue, May 23, 2006 at 01:14:54PM -0700, Hans Reiser wrote:
> >  
> >
> >>underlying FS can be improved.  Performance results show that the new
> >>code consumes  40% less CPU when doing "dd bs=1MB ....." (your hardware,
> >>and whether the data is in cache, may vary this result).  Note that this
> >>has only a small effect on elapsed time for most hardware.
> >>    
> >>
> >
> >Write requests in linux are restricted to one page?
> >
> >  
> >
> It may go to the kernel as a 64MB write, but VFS sends it to the FS as
> 64MB/4k separate 4k writes.

Nonsense, there are ways to get > PAGE_CACHE_SIZE writes in one chunk.
Other file systems have been doing it for years.

-- 
Jens Axboe


  reply	other threads:[~2006-06-08 10:58 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-05-23 20:14 [PATCH] updated reiser4 - reduced cpu usage for writes by writing more than 4k at a time (has implications for generic write code and eventually for the IO layer) Hans Reiser
2006-05-23 20:26 ` Alexey Polyakov
2006-05-23 20:33   ` Michal Piotrowski
2006-05-24 14:39     ` Vladimir V. Saveliev
2006-06-08 10:45       ` Jan Engelhardt
2006-06-08 12:40         ` Vladimir V. Saveliev
2006-06-08 14:11           ` Jan Engelhardt
2006-05-24 17:53 ` Tom Vier
2006-05-24 17:55   ` Hans Reiser
2006-06-08 11:00     ` Jens Axboe [this message]
2006-06-08 11:26       ` Vladimir V. Saveliev
2006-06-08 11:35         ` Jens Axboe
2006-06-08 12:08           ` Vladimir V. Saveliev
2006-06-14 19:37           ` Hans Reiser
2006-06-08 12:10         ` Christoph Hellwig
2006-06-14 22:08           ` batched write Vladimir V. Saveliev
2006-06-17 17:04             ` Andrew Morton
2006-06-17 17:51               ` Hans Reiser
2006-06-18 11:20                 ` Nix
2006-06-19  9:05                   ` Hans Reiser
2006-06-19 11:32                     ` Miklos Szeredi
2006-06-19 16:39                       ` Hans Reiser
2006-06-19 17:35                         ` Miklos Szeredi
2006-06-19 17:52                           ` Akshat Aranya
2006-06-19 20:39                             ` Hans Reiser
2006-06-19 16:27               ` Andreas Dilger
2006-06-19 16:51                 ` Hans Reiser
2006-06-19 18:50                   ` Andreas Dilger
2006-06-19 20:47                     ` Hans Reiser
2006-06-20  0:01                     ` David Chinner
2006-06-20  7:19                       ` Hans Reiser
2006-06-20  7:26                         ` Andrew Morton
2006-06-20  9:02                           ` Steven Whitehouse
2006-06-20 16:26                           ` Vladimir V. Saveliev
2006-06-20 17:29                             ` Hans Reiser
2006-06-19 18:28                 ` Vladimir V. Saveliev
2006-05-24 17:59   ` [PATCH] updated reiser4 - reduced cpu usage for writes by writing more than 4k at a time (has implications for generic write code and eventually for the IO layer) Hans Reiser

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