Re: [PATCH 3/3] mm: slub: Default slub_max_order to 0

James Bottomley
2011-05-12T20:04:20Z

On Thu, 2011-05-12 at 14:44 -0500, James Bottomley wrote:
> On Thu, 2011-05-12 at 13:37 -0500, James Bottomley wrote:
> > On Thu, 2011-05-12 at 18:55 +0300, Pekka Enberg wrote:
> > > On Thu, 2011-05-12 at 10:43 -0500, James Bottomley wrote:
> > > > However, since you admit even you see problems, let's concentrate on
> > > > fixing them rather than recriminations?
> > >
> > > Yes, please. So does dropping max_order to 1 help?
> > > PAGE_ALLOC_COSTLY_ORDER is set to 3 in 2.6.39-rc7.
> >
> > Just booting with max_slab_order=1 (and none of the other patches
> > applied) I can still get the machine to go into kswapd at 99%, so it
> > doesn't seem to make much of a difference.
> >
> > Do you want me to try with the other two patches and max_slab_order=1?
>
> OK, so patches 1 + 2 plus setting slub_max_order=1 still manages to
> trigger the problem (kswapd spinning at 99%). This is still with
> PREEMPT; it's possible that non-PREEMPT might be better, so I'll try
> patches 1+2+3 with PREEMPT just to see if the perturbation is caused by
> it.

Confirmed, I'm afraid ... I can trigger the problem with all three
patches under PREEMPT. It's not a hang this time, it's just kswapd
taking 100% system time on 1 CPU and it won't calm down after I unload
the system.

James