Re: [00/17] Large Blocksize Support V3

Nick Piggin
2007-04-27T10:22:16Z

William Lee Irwin III wrote:
> 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).

Just a random aside question... doesn't Oracle db do direct IO from
hugepages?

--
SUSE Labs, Novell Inc.