Because of a lot of unwarranted
criticizms of my previous rigorous and outstanding :)
benchmark and because I am lucky to come
across a bargain maxtor drive I have done the test
again.
It put the same hard drive in both amd 1.33GHz
and celeron 566MHz machine with exactly
the same controller that comes with the drive.
It's promise PDC20269 chipset and
I have to run 2.4.19-pre7-ac2 to detect this
controller and linux detects it as udma_133 drive.
I point PGDATA to the directory on this hard drive on both machines.
On amd
# hdparm -tT /dev/hde
/dev/hde:
Timing buffer-cache reads: 128 MB in 0.78 seconds =164.10 MB/sec
Timing buffered disk reads: 64 MB in 1.59 seconds = 40.25 MB/sec
On celeron the first number is around 100 MB/sec and
the second number is about the same. The drive is not in that
system anymore and I didn't write the numbers down.
The minimun time to vacuum on celeron I got was 61 seconds
and whereas on amd it is 59 seconds. So it looks like vacuuming
scales very linearly with hdparm results.
And yes, with on board ide controller, AMD/sis box hdparm bottleneck is around
24MB/sec whereas corresponding number for intel box is 30MB/sec.
The moral I get from this benchmark is that AMD is certainly
not much better preformance/price wise at least not for
a database server
In fact for various reasons I am going to go with an intel
box.
Another gripe I have is that vacuum process does not eat up 100%
of cpu. In the beginning it peaks around 80% and at the end
it is stuck around 20%.
Whenever I have a long running process and
it is not eating up 100% of cpu I feel I am not getting my money's
worth for the cpu. I wonder why vacuum process is not more parallelized
if at all. I can imagine manually vacuuming many tables in parallel
and it might eat up all cpu and I wonder whether it might finish quicker.
