fastboot, diskstat

[bert hubert <bert.hubert@netherlabs.nl>]

Hi Andrew,

I'm currently at OLS and presented http://ds9a.nl/diskstat yesterday, which
also references your ancient 'fboot' program.

I've also done experiments along those lines, and will be doing more of them
soon. 

You mention it was a waste of time, do you recall if that meant:

1) that the total time for prefetching + actual boot was only 10% shorter,
but that the actual booting did not (significantly) touch the disk?

2) that on actual boot there would still be a lot of i/o

?

Regarding 1), in my own experiments I failed to convince the kernel to
actually cache the pages I touched, I wonder if some sequential-read
detection kicked in, the one that prevents entire cd's being cached.

For my next attempt I'll try to actually lock the pages into memory.

Also, regarding the directory entries, are they accessed via the buffer
cache? Iow, would reading blocks which can't be mapped to files directly via
/dev/hda be useful?

Thanks!

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