Re: Speeding up fsck 2 times
Jan Kara (jack@atrey.karlin.mff.cuni.cz)
Mon, 14 Jun 1999 22:18:35 +0200
> >>>>> "Pavel" == Pavel Machek <pavel@bug.ucw.cz> writes:
> > I do not know if I should attempt official kernel integration. I
> > probably can make it per mount option pretty easily.
> We just have to come up with the worst case and a benchmark for it so we
> can try it on various configs. Is linear access to a big
> file the worst case ? Isn't there something worse ?
Worst case would be reading two blocks which are on the "reference block
boundary" - one block referenced as last one in the block so for next one we
have to read in reference block which would mean seek - read block - seek -
read data block instead of current read block - read data block. But this is
not very probable case so the worst reasonable case would be linear reading
(long at least a few MB) of file large enough in the part where are triple
indirects... But as we are going to loose only each 256KB when using 1KB
blocks I don't think we will loose more than a few percents (my personal
estimation is <5%).
Honza.
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