Re: optimal file order for reading from disk

[P@draigBrady.com]

bert hubert wrote:
> 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.

Thanks for that. Yep I'm torn between sorting by inode which
should be good for new filesystems, but maybe sorting by
path would be better for mature filesystems?

> 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.

I found some interesting into here thanks:
http://kerneltrap.org/node/2157

cheers,
Pádraig.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/