2004-06-19 15:30:53

by Holger Kiehl

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Subject: SATA performance drop in 2.6.7

Hello

Anybody noticed that with 2.6.7 the performance of SATA disks
drops drastically. Right after a boot I get the following with
hdparm:

Timing buffer-cache reads: 3724 MB in 2.00 seconds = 1861.35 MB/sec
Timing buffered disk reads: 166 MB in 3.03 seconds = 54.72 MB/sec

It then starts to degrate rapidly:

Timing buffer-cache reads: 2560 MB in 2.00 seconds = 1280.19 MB/sec
Timing buffered disk reads: 166 MB in 3.01 seconds = 55.14 MB/sec

Timing buffer-cache reads: 2164 MB in 2.00 seconds = 1081.08 MB/sec
Timing buffered disk reads: 166 MB in 3.02 seconds = 55.05 MB/sec

Timing buffer-cache reads: 1700 MB in 2.00 seconds = 850.13 MB/sec
Timing buffered disk reads: 146 MB in 3.04 seconds = 48.07 MB/sec

Then about 3 minutes after boot it stays at approx.

Timing buffer-cache reads: 780 MB in 2.00 seconds = 389.67 MB/sec
Timing buffered disk reads: 102 MB in 3.01 seconds = 33.89 MB/sec

Controller is a Intel ICH5R and disk is Seagate ST380013AS. With kernel
2.6.6 this does not happen. On another PATA system with 2.6.7 this
does not happen, so I assume the problem must be with SATA.

Holger

PS: Please CC me since I am not subscribed.