Messages in this thread |  | | | Subject | SMP 2.1.131: SCSI performance extremely poor vs. IDE | | From | Ben Gertzfield <> | | Date | 08 Dec 1998 16:31:07 -0800 |
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I've received a report of extremely poor SCSI performance in the late 2.1.x kernels and verified this under 2.1.131.
I tested this by untarring the mozilla source onto the local hard drive, syncing, and rm -rf ing it.
The mozilla source is 91.6 megabytes untarred.
The results are astounding:
[ben@gilgamesh:/tmp]% time rm -rf mozilla 4:15PM rm -rf mozilla 0.13s user 0.93s system 18% cpu 5.581 total
[ben@beowulf:/tmp]% time rm -rf mozilla 4:15PM rm -rf mozilla 0.17s user 1.51s system 98% cpu 1.712 total
This is, frankly, terrible. Since when is IDE three times faster than ultra-wide SCSI?
The first computer, gilgamesh, is a SCSI-based Pentium II/333 system; using the aic7xxx driver version 5.1.4/3.2.4 for its Adaptec AHA-294X Ultra Wide SCSI controller to control an IBM DDRS-39130W ultra-wide drive.
The second computer, beowulf, is an IDE-based dual Pentium Pro/200 system, PIIX3 IDE controller, ST39140A IDE drive.
Both are compiled with SMP = 1.
One would think that the SCSI Pentium II/333 system, even though it's single-processor, would have decent disk performance! Is there something I'm missing?
So as to not spam the list with the .configs of the two machines, I've put them up on the Web for your perusal:
http://csl.cse.ucsc.edu/~ben/ide-config http://csl.cse.ucsc.edu/~ben/scsi-config
What would cause this kind of performance loss?
For an interesting comparison, here's the same test on an UltraSPARC:
bash$ time rm -rf mozilla/
real 1.1 user 0.2 sys 0.7
Ben
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