Re: [patch 4/4] powerpc 2.6.21-rt1: reduce scheduling latency by changing tlb flush size

[Tsutomu OWA <tsutomu.owa@toshiba.co.jp>]

At Mon, 14 May 2007 16:40:02 +0200, Arnd Bergmann wrote:
>=20
> On Monday 14 May 2007, Tsutomu OWA wrote:
> > --- linux-2.6.21-rt1/include/asm-powerpc/tlbflush.h=A0=A0=A0=A0=A02007-=
04-26 12:08:32.000000000 +0900
> > +++ rt/include/asm-powerpc/tlbflush.h=A0=A0=A02007-05-14 16:12:47.00000=
0000 +0900
> > @@ -25,7 +25,12 @@ struct mm_struct;
> > =A0#include <linux/percpu.h>
> > =A0#include <asm/page.h>
> > =A0
> > +#if defined(CONFIG_PPC_CELLEB) && defined(CONFIG_PREEMPT_RT)
> > +/* Since tlb flush takes long time on Celleb, reduce it to 1 when Cell=
eb && RT */
> > +#define PPC64_TLB_BATCH_NR 1

> With this code, you get silent side-effects of enabling PPC_CELLEB
> along with another platform.

  Yeah, thank you for pointing it out.
  I'll send revised patch later.

> Maybe instead you should change the hpte_need_flush() to always flush
> when running on the celleb platform and PREEMPT_RT is enabled.

  Hmm... Is it in linux-2.6.21?  grep'ing it did not help...=20

  Is http://patchwork.ozlabs.org/linuxppc/patch?id=3D10361 is the first pla=
ce
where the hpte_need_flush() appears?

-- owa