Re: [patch] speed up single bio_vec allocation

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

On Fri, Dec 08 2006, Chen, Kenneth W wrote:
> > Chen, Kenneth wrote on Wednesday, December 06, 2006 10:20 AM
> > > Jens Axboe wrote on Wednesday, December 06, 2006 2:09 AM
> > > This is what I had in mind, in case it wasn't completely clear. Not
> > > tested, other than it compiles. Basically it eliminates the small
> > > bio_vec pool, and grows the bio by 16-bytes on 64-bit archs, or by
> > > 12-bytes on 32-bit archs instead and uses the room at the end for the
> > > bio_vec structure.
> > 
> > Yeah, I had a very similar patch queued internally for the large benchmark
> > measurement.  I will post the result as soon as I get it.
> 
> 
> Jens, this improves 0.25% on our db transaction processing benchmark setup.
> The patch tested is (on top of 2.6.19):
> http://marc.theaimsgroup.com/?l=linux-kernel&m=116539972229021&w=2

Ok, well it's not much but if it's significant it's not too bad either
:-)

Some tests I ran locally showed it being _slower_, which is a little
odd. They were basically hammering requests through the block layer with
a null end.

-- 
Jens Axboe