Re: [Demo program]: Poor elevator performance in 2.4.0-test9pre6

From: Jens Axboe (axboe@suse.de)
Date: Mon Sep 25 2000 - 09:00:51 EST


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.

-- 
* Jens Axboe <axboe@suse.de>
* SuSE Labs
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