Sucky performance under disk load
This is with my Dell Latitude C600. Somewhat recently, I've noticed
that, when there's heavy disk activity, the entire system grinds
almost to a halt. I suspect I've noticed it more since I've installed
postgresql and imported a reasonably large data set into it; running
VACUUM FULL ANALYZE over the database will kill the system. The daily
updatedb process also hurts a lot.
The symptom is just that everything is reeeallly
slloooowwwww... playing Vorbis files under xmms breaks a lot, the
mouse is unresponsive and jerky, and so on. If I watch what's going
on using, say, mgm, there's somewhat minimal disk traffic (perhaps
4-8k sectors/second read, peaks up to 32k sectors) and basically no
CPU cycles being used. Poking with top suggests that both postmaster
(the postgresql server) and kjournald are blocking; is ext3fs hurting
me unnecessarily here?
AFAIK I've set up everything that wants to be with hdparm, including
IRQ unmasking, 32-bit I/O, and DMA. There's no particular hints in
the system logs that anything is amiss ("PIIX4: not 100% native mode:
will probe irqs later", but this doesn't sound like the end of the
world).
Any hints?
--
David Maze dmaze@debian.org http://people.debian.org/~dmaze/
"Theoretical politics is interesting. Politicking should be illegal."
-- Abra Mitchell
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