Re: [PATCH 0/4] Page based O_DIRECT v2

Jens Axboe
2009-08-20T10:40:00Z

On Wed, Aug 19 2009, Alan D. Brunelle wrote:
> On Thu, 2009-08-20 at 00:06 +0200, Jens Axboe wrote:
>
> >
> > Thanks a lot for the test run, Alan. I wonder why writes are down while
> > reads are up. One possibility could be a WRITE vs WRITE_ODIRECT
> > difference, though I think they should be the same. The patches I posted
> > have not been benchmarked at all, it's still very much a work in
> > progress. I just wanted to show the general direction that I thought
> > would be interesting. So I have done absolutely zero performance
> > testing, it's only been tested for whether it still worked or not (to
> > some degree :-)...
> >
> > I'll poke a bit at it here, too. I want to finish the unplug/wait
> > problem first. Is your test case using read/write or readv/writev?
> >
>
> Hi Jens - I just had some extra cycles, so figured what the heck... :-)
>
> Actually, this is using asynchronous direct I/Os (libaio/Linux native
> AIO). If I get a chance tomorrow, I'll play with read/write (and/or
> readv/writev).

OK, then I wonder what the heck is up... Did you catch any io metrics?

--
Jens Axboe