Re: The difference of request dir between AS and Deadline I/O scheduler?

[Aaron Carroll]

èç wrote:
> On Tue, Mar 3, 2009 at 12:21 PM, Aaron Carroll <aaronc@xxxxxxxxxxxxxxx> wrote:
> > ï wrote:
> > > Hi,
> > >
> > > I'm little confused about the defination of request dir in AS and
> > > Deadline I/O scheduler.
> > > In AS, the request dir is defined by wheher it's sync:
> > >
> > > data_dir = rq_is_sync(rq);
> > >
> > > But in Deadline, the requests are grouped by read and write.
> > >
> > > Why is there the difference since AS is an extension of Deadline?
> > > what's the consideration?
> > I also thought it was silly to have different behaviours, so I tried
> > the following patch that makes deadline use sync/async instead of
> > read/write.  All the benchmarks I tried showed that performance
> > dropped or remained constant at best, so I didn't propose it.
> > Maybe you will have more luck...
> Hello,
> Which benchmark tool do you use? I'd like to have a try. I think the
> I/O behavior is an important factor which can affect the performance.

I can't find the original results, but from memory I tried FIO (many
random readers with various I/O sizes), postmark, and compilebench
on a single-disk and 10-disk hardware RAID system.


   -- Aaron
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