Re: adventures in booting

[Havoc Pennington <hp redhat com>]

On Thu, 2004-12-02 at 12:40 -0500, David Zeuthen wrote:
> 
> To me it makes more sense to look at this on the block level than on the
> file level; remember, a lot the files in my readahead set stems from
> stat'ing files - for example, there are more than 2200 distinct .png
> files in my readahead set. We probably only need one sector from most of
> those (the inode) rather than the entire file.
> 
> I'm almost positive it requires kernel changes to do this the right way;
> one naive idea is to have a userspace daemon, capturing what blocks are
> read when (kernel tells this daemon using the kernel events layer). This
> would run in the first three minutes on each and every boot. When the
> system is idle (and only when running on AC power!) another daemon
> rearranges blocks on the disk. What blocks to rearrange could be the
> result of a computation involving several three-minute result sets.

Stephen Tweedie mentioned some ideas for what could be done in the
kernel to optimize this stuff, I don't know specifics.

Havoc