Powersaving and disk activity

While I was away over xmas I spent a lot of time using my aging laptop (a P2-300Mhz woo!), mainly as a big ebook reader and mp3 player. One of the things I found is that while there are lots of powersaving utilities out there for linux, none of them actually bloody work! Not because of any flaw in the programs themselves mind, but because other programs are continually demanding resources (CPU, HD etc.) that reset whatever powersaving measures are in place and bring everything back online.

The stuff that accesses the disk is the worst, because there seems to be no way to figure out what program is actually causing the noisy thing to spin back up. I’m sat there in almost perfect silence, then wheeeeeeKRKRKRwhooooo as the drive spins up, does something then spins down again, every minute or so. I start looking for cpu activity via top and the like to correspond with the disk activity to try and identify the culprits with little success.

I did find some things, one amusing one was acpid the ACPI daemon that is responsible for putting things into powersave mode was writing to a log file every few seconds and thus preventing itself from doing it’s job. Even noflushd, which is supposed to prevent just this scenario by caching disk accesses in RAM (and potentially losing your data as a result) didn’t help. If I were running windows I would just fire up FileMon from sysinternals which would show me exactly what program is accessing the disk, but I can’t find anything similar for linux.

I hate to admit it, but I actually considered putting windows back on the thing, but then I realised by the time I got it all patched and extra firewall/antivirus installed so it could actually be used safely it would be time to come back home and I abandoned that idea .