Re: [PATCH 5/15] cfq-iosched: speed up rbtree handling

[Jens Axboe <jens.axboe@oracle.com>]

On Wed, Apr 25 2007, Jens Axboe wrote:
> On Wed, Apr 25 2007, Jens Axboe wrote:
> > On Wed, Apr 25 2007, Alan D. Brunelle wrote:
> > > Hi Jens -
> > > 
> > > The attached patch speeds it up even more - I'm finding a >9% reduction 
> > > in %system with no loss in IO performance. This just sets the cached 
> > > element when the first is looked for.
> > 
> > Interesting, good thinking. It should not change the IO pattern, as the
> > end result should be the same. Thanks Alan, will commit!
> > 
> > I'll give elevator.c the same treatment, should be even more beneficial.
> > Stay tuned for a test patch.
> 
> Something like this, totally untested (it compiles). I initially wanted
> to fold the cfq addon into the elevator.h provided implementation, but
> that requires more extensive changes. Given how little code it is, I
> think I'll keep them seperate.

Booted, seems to work fine for me. In a null ended IO test, I get about
a 1-2% speedup for a single queue of depth 64 using libaio. So it's
definitely worth it, will commit.

-- 
Jens Axboe