Re: [00/17] Large Blocksize Support V3

William Lee Irwin III
2007-04-27T00:31:55Z

William Lee Irwin III <wli@holomorphy.com> writes:
>> In memory as on disk, contiguity matters a lot for performance.

On Thu, Apr 26, 2007 at 12:21:24PM -0600, Eric W. Biederman wrote:
> Not nearly so much though. In memory you don't have seeks to avoid.
> On disks avoiding seeks is everything.

I readily concede that seeks are most costly. Yet memory contiguity
remains rather influential.

Witness the fact that I'm now being called upon a second time to
adjust the order in which mm/page_alloc.c returns pages for the
sake of implicitly establishing IO contiguity (or otherwise
determining why things are coming out backward now).

-- wli