Extremely slow hard disk performance in FC3.

[Ismael Juma]

Hi,

I have been experiencing some odd behaviour (major slowdowns) in my
laptop for some weeks now. After some investigation it turned out that
hard disk performance was the reason. My buffered reads were way below
the average when running hdparm -tT /dev/hda. However, this only
occurred at some points in time. Since it was hard to reproduce I did
not report the problem.

Yesterday I have finally been able to narrow down the cause of the
problem. This slowdown occurs if my cd-rom drive is open or if there is
no disk in it. Even though I don't understand how this is possible, the
figures from hdparm -tT /dev/hda follow:

With a cd in the cd-rom drive (average of three runs):
/dev/hda:
 Timing cached reads:   605.79 MB/sec
 Timing buffered disk reads:   29.90 MB/sec

With the cd-rom drive open (average of three runs):
/dev/hda:
 Timing cached reads:  594.06 MB/sec
 Timing buffered disk reads:   5.11 MB/sec

With cd-rom drive closed but with no cd in it (average of three runs):
/dev/hda:
 Timing cached reads:  593.94 MB/sec
 Timing buffered disk reads:   14.7 MB/sec

My system is a Dell Inspiron 8200 laptop (P4M 1.9 Ghz, 1 GB RAM, Geforce
4 Go 64 MB RAM) and /dev/hda is a Hitachi Travelstar 7k60 (7200 RPM
drive). I also have an external firewire drive that does not exhibit any
of the problems mentioned.

I'm using a fully updated Fedora Core 3 with a 2.6.10-rc2 kernel and KDE
3.3.1. I have experienced this problem with earlier kernels though. It
is important to note that the current problem is _always_ reproducible.

Has anyone experience a similar problem? Should I file a bug report and
if yes, against what component?

Thanks in advance.

Regards,
Ismael

P.S. DMA is enabled.