Messages in this thread | | | Date | Thu, 4 Apr 2002 23:45:55 -0800 (PST) | From | dean gaudet <> | Subject | Re: faster boots? |
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On Thu, 4 Apr 2002, Andrew Morton wrote:
> I guess the greatest benefit would come from reorganising the > layout of the root filesystem's data and metadata so the > pagecache prepopulation doesn't have to seek all over the place.
windows xp does this automatically (but it takes a lot of idle time before it'll start playing with your disk)... search for "bootvis" at microsoft.com, that tool can force the reorganization to occur. it's worth 10%ish there as well (quite noticeable on laptops). they appear to reorganize the boot-time files into one big contiguous region. that's fetched into their equivalent of the page cache with sequential reads.
it's certainly interesting theory -- trying to do disk layout which is optimised for particular access patterns... it's kind of a hack to do this just for boot time, but definitely educational :)
in some ways, the filesystem is the wrong place to do this type of activity -- you could approach the problem as a block layer device between the fs and the hardware which maintains statistics on access patterns and moves blocks around to optimise access time -- which lets you fix all sorts of seeking problems. i guess the challenge would be maintaining a map of logical block number to physical block number. hmm. guess that's kind of hard.
-dean
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