Re: Linux 2.6.29

Jens Axboe
2009-04-03T07:25:26Z

On Thu, Apr 02 2009, Linus Torvalds wrote:
>
> Jens - remind us what the problem with AS was wrt CFQ?

CFQ was just faster, plus it supported things like io priorities that AS
does not.

> There's some write throttling in CFQ, maybe it has some really broken
> case?

Who knows, it's definitely interesting and something to look into why AS
performs that differently to CFQ on his box. Lennart, can you give some
information on what file system + mount options, disk drive(s), etc? A
full dmesg would be good, too.

>
> Linus
>
> On Fri, 3 Apr 2009, Lennart Sorensen wrote:
>
> > On Thu, Apr 02, 2009 at 03:00:44AM +0200, Ingo Molnar wrote:
> > > I'll test this (and the other suggestions) once i'm out of the merge
> > > window.
> > >
> > > I probably wont test that though ;-)
> > >
> > > Going back to v2.6.14 to do pre-mutex-merge performance tests was
> > > already quite a challenge on modern hardware.
> >
> > Well after a day of running my mythtv box with anticipatiry rather than
> > the default cfq scheduler, it certainly looks a lot better. I haven't
> > seen any slowdowns, the disk activity light isn't on solidly (it just
> > flashes every couple of seconds instead), and it doesn't even mind
> > me lanuching bittornado on multiple torrents at the same time as two
> > recordings are taking place and some commercial flagging is taking place.
> > With cfq this would usually make the system unusable (and a Q6600 with
> > 6GB ram should never be unresponsive in my opinion).
> >
> > So so far I would rank anticipatory at about 1000x better than cfq for
> > my work load. It sure acts a lot more like it used to back in 2.6.18
> > times.
> >
> > --
> > Len Sorensen
> >

--
Jens Axboe