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SubjectRe: Lower disk performance with 2.3.9....
On Tue, 6 Jul 1999, Daniel J Blueman wrote:

> This is the output from hdparm -T /dev/hda:
>
> Linux 2.3.5:
> /dev/hda:
> Timing buffer-cache reads: 64 MB in 0.50 seconds =128.00 MB/sec
>
> Linux 2.3.9:
> /dev/hda:
> Timing buffer-cache reads: 64 MB in 0.53 seconds =120.75 MB/sec

Try it a bunch of times and it will vary by more than that percentage.
Let us assume that all is identical.........bad assumption....

/dev/hda:
Timing buffer-cache reads: 128 MB in 3.03 seconds =42.24 MB/sec
Timing buffered disk reads: 64 MB in 11.16 seconds = 5.73 MB/sec

/dev/hda:
Timing buffer-cache reads: 128 MB in 3.08 seconds =41.56 MB/sec
Timing buffered disk reads: 64 MB in 4.55 seconds =14.07 MB/sec

/dev/hda:
Timing buffer-cache reads: 128 MB in 3.00 seconds =42.67 MB/sec
Timing buffered disk reads: 64 MB in 4.61 seconds =13.88 MB/sec

/dev/hda:
Timing buffer-cache reads: 128 MB in 3.01 seconds =42.52 MB/sec
Timing buffered disk reads: 64 MB in 5.38 seconds =11.90 MB/sec

/dev/hda:
Timing buffer-cache reads: 128 MB in 3.48 seconds =36.78 MB/sec
Timing buffered disk reads: 64 MB in 4.35 seconds =14.71 MB/sec

/dev/hda:
Timing buffer-cache reads: 128 MB in 3.48 seconds =36.78 MB/sec
Timing buffered disk reads: 64 MB in 4.33 seconds =14.78 MB/sec

As you can see that it rides a wave based on activity of stuff running.

> That's a ~9% decrease in buffer-cache reads.

36.78/42.24 varies by 1/7th of max buffer-cache reads.

Oh well............

Andre Hedrick
The Linux IDE guy



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