Bruce Evans wrote:
On Tue, 17 Feb 2009, Gary Jennejohn wrote:
I tested this with an Adaptec 29160. I saw no real improvement in
performance, but also no regressions.
I suspect that the old disk I had attached just didn't have enough
performance reserves to show an improvement.
My test scenario was buildworld. Since /usr/src and /usr/obj were both
on the one disk it got a pretty good workout.
^^^^ low
AMD64 X2 (2.5 GHz) with 4GB of RAM.
Buildworld hardly uses the disk at all. It reads and writes a few hundred
MB. Ideally the i/o should go at disk speeds of 50-200MB/S and thus take
between 20 and 5 seconds. In practice, it will take a few more seconds.
physically but perhaps even less virtually due to parallelism.
Bruce
Yes, on modern machines, buildworld is bound almost completely by disk
latency, and not at all by disk or controller bandwidth.
Scott
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