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Salut,

On Mon, May 08, 2006 at 01:23:22PM +0200, Manuel Bouyer wrote:
> Can you try the attached program ? It will benchmark the IDE bus's bandwi=
dth:
> ./tst /dev/rwd0d 10000
>=20
> it should run for a few seconds to give usefull results; if it doesn't
> use something larger than 10000

I added the O_SYNC parameter to your open() and it sanitized the output
quite a bit:

vic# ./tst /dev/rwd0d 10000                                                =
    =20
5409749 us, 115.532162 MB/s                                                =
    =20
vic#=20

Bonnie gives the following output:

    -------Sequential Output-------- ---Sequential Input-- --Random--
    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
 MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
256  4802  3.5  5217  1.8  6430  1.8 105399 75.6 627604 100.0 5970.5 31.6

The worst thing is that sometimes disk I/O operations hang for quite a
while during heavy disk I/O (especially when the I/O takes place from two
or more programs, so it seems that the I/O bandwidth isn't really
distributed equally). I might bring up more test cases on that tonight.

It looks to me that either the VM can't stand much parallel I/O or that
there is a speed issue in the file system layer.

				Tonnerre

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