Re: faster boots?

[Jeremy Jackson]

It may be interesting to note that SGI's XFS has a
"realtime section" or some such, which has no metadata,
only data blocks.  Perhaps DMAPI has methods for moving
files around on a live fs.  If you know what you want in there.

Jeremy

----- Original Message -----
From: "dean gaudet" <[e-mail]>
To: "Andrew Morton" <[e-mail]>
Cc: <[e-mail]>; <[e-mail]>
Sent: Thursday, April 04, 2002 11:45 PM
Subject: Re: faster boots?

> 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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