Re: optimal file order for reading from disk

bert hubert
2005-06-14T12:13:24Z

On Tue, Jun 14, 2005 at 12:21:40PM +0100, P@draigBrady.com wrote:
> I know this will be dependent on filesystem, I/O scheduler, ...
> but given a list of files, what is the best (filesystem
> agnostic) order to read from disk (to minimise seeks).
>
> Should I sort by path, inode number, getdents, or something else?

I know several projects that sort on inode number and benefit from that,
sometimes in a big way. The effect of this will probably be less on a
matured filesystem image.

I can't really explain why it helps though. I don't think the kernel will do
'crossfile readahead', although your disk might do so.

Google on 'orlov allocator', is enlightning.

--
http://www.PowerDNS.com Open source, database driven DNS Software
http://netherlabs.nl Open and Closed source services