Messages in this thread |  | | Date | Wed, 11 Oct 2000 01:06:11 +0100 (BST) | From | Chris Evans <> | Subject | 2.4.0test9 vm: disappointing streaming i/o under load |
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Hi,
Finally got round to checking out 2.4.0test9.
Unfortunately, 2.4.0test9 exhibits poor streaming i/o performance when under a bit of memory pressure.
The test is this: boot with mem=32M, log onto GNOME and start xmms playing a big .wav ripped from a CD (this requires 100-200k read i/o per second).
Then, I start then kill netscape. I then started a find / and started gnumeric firing up at the same time.
Results =======
2.2 RH7.0: the music skipped maybe twice briefly during the test.
2.4.0test9: music stuttered repeatedly while netscape started. Worse, when firing up gnumeric with the find / on the go, there were big pauses in sound output. On pause was over 5 seconds!!!
So not so hot.
Could this perhaps be related to the drop_behind magic penalizing streaming i/o pages too much? Perhaps the greater ago on the i/o pages means that when there is a little memory pressure, they are getting thrown out the page cache before the app (xmms) gets a chance to use them!
Might it be useful for me to try pre10-1, I note it has more "balancing fixes".
Cheers Chris
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