[Gllug] Poor disk performance - help

[Alain Williams]

Hi,

I have just replaced my motherboard & CPU - but disk I/O is abysmal.
I have AMD Athlon XP 3000+ running at 2166 MHz, I have 1G ddr 333MHz RAM.
Soltek motherboard (SLKT600-RL).
I have IDE 2 disks & 2 CDs.

Machine seems OK except that disk i/o is slooow and uses vast amounts of CPU, I first
noticed it when a ftp from a local machine was ~2Mbyte/sec with 50->100% cpu, I would
expect ~10MB/sec.

If I do a disk read:
	# time dd if=/dev/hda10 of=/dev/null bs=1M count=100
	100+0 records in
	100+0 records out
 
	real    0m12.903s
	user    0m0.010s
	sys     0m11.380s

Note the high system time. It doesn't seem to be the machine in general as if I immediately
repeat (ie from buffer cache) I get:

	# time dd if=/dev/hda10 of=/dev/null bs=1M count=100
	100+0 records in
	100+0 records out
 
	real    0m0.324s
	user    0m0.000s
	sys     0m0.270s

If I do this on what should be a much slower machine (1GHz Duron, 512Mb RAM) I get:

	# time dd if=/dev/hda2 of=/dev/null bs=1M count=100
	100+0 records in
	100+0 records out
 
	real    0m3.512s
	user    0m0.000s
	sys     0m0.930s

Note that the system time is a much smaller fraction of the real time.

(You can see that it is slower as if I immediately repeat:
	# time dd if=/dev/hda2 of=/dev/null bs=1M count=100
	100+0 records in
	100+0 records out
 
	real    0m0.646s
	user    0m0.000s
	sys     0m0.640s
)


OK, so I have got something screwed - but what, any idea where I should start looking ?


-- 
Alain Williams

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FATHERS-4-JUSTICE - Campaigning for equal rights for parents and the
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