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)
- From: Jens Axboe <axboe@xxxxxxx>
- Date: Thu, 8 Jun 2006 13:00:45 +0200
On Wed, May 24 2006, Hans Reiser wrote:
Tom Vier wrote:
On Tue, May 23, 2006 at 01:14:54PM -0700, Hans Reiser wrote:It may go to the kernel as a 64MB write, but VFS sends it to the FS as
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?
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
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