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SubjectRe: [Demo program]: Poor elevator performance in 2.4.0-test9pre6
On Mon, Sep 25, 2000 at 04:00:51PM +0200, Jens Axboe wrote:
> On Mon, Sep 25 2000, Robert Cohen wrote:
> > With kernel version 2.4.0-test9pre6 the results are as follows.
> > The test machine has 128 Megs of memory. The tests accesses 240 Megs of
> > files so that it can't fit in cache.
> >
> > If I run it with 8 files of size 30 Megs:
> >
> > [robert@test25 src]$ ./elv_test 8 30
> > files created, 240 megs written at 8.96 megs/sec
> > finished writing 240 megs written at 1.05 megs per sec <<<<<<
> > finished reading, 240 megs read at 5.848833 megs/sec
> >
> > If I do the same with a single file of size 240 Megs
> >
> > [robert@test25 src]$ ./elv_test 1 240
> > files created, 240 megs written at 11.12 megs/sec
> > finished writing 240 megs written at 11.08 megs per sec
> > finished reading, 240 megs read at 12.580521 megs/sec
>
> axboe@burns:/opt/software/testing > ./elv_test 8 30
> files created, 240 megs written at 21.64 megs/sec
> finished writing 240 megs written at 21.12 megs per sec
>
> This is my current tree on 2.4.0-test9-pre5. Thanks for the test program,
> Andrea and I are working on getting a polished patch ready for inclusion
> that (apparently) also fixes this problem.

I doubt this has any relevance whatsoever, but when I try this on a 2.2.16
kernel running on top of a Pentium Pro 200 w/96megs of mem w/ a SCSI 2
disk, I get some funny numbers:

matt@zeus:~/cwork/personal$ ./elv_test 8 30
files created, 240 megs written at 4.32 megs/sec
finished writing 240 megs written at 1794.23 megs per sec
finished reading, 240 megs read at 1675.813817 megs/sec

Any ideas why I would be getting these numbers?
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