From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@ozlabs.org, Thomas Gleixner <tglx@linutronix.de>,
mingo@elte.hu, linux-kernel@vger.kernel.org
Subject: Re: [patch 4/4] powerpc 2.6.21-rt1: reduce scheduling latency by changing tlb flush size
Date: Tue, 15 May 2007 17:23:09 +1000 [thread overview]
Message-ID: <1179213789.32247.166.camel@localhost.localdomain> (raw)
In-Reply-To: <200705141640.02561.arnd@arndb.de>
On Mon, 2007-05-14 at 16:40 +0200, Arnd Bergmann wrote:
> On Monday 14 May 2007, Tsutomu OWA wrote:
> > --- linux-2.6.21-rt1/include/asm-powerpc/tlbflush.h 2007-04-26 12:08:32.000000000 +0900
> > +++ rt/include/asm-powerpc/tlbflush.h 2007-05-14 16:12:47.000000000 +0900
> > @@ -25,7 +25,12 @@ struct mm_struct;
> > #include <linux/percpu.h>
> > #include <asm/page.h>
> >
> > +#if defined(CONFIG_PPC_CELLEB) && defined(CONFIG_PREEMPT_RT)
> > +/* Since tlb flush takes long time on Celleb, reduce it to 1 when Celleb && RT */
> > +#define PPC64_TLB_BATCH_NR 1
> > +#else
> > #define PPC64_TLB_BATCH_NR 192
> > +#endif /* defined(CONFIG_PPC_CELLEB) && defined(CONFIG_PREEMPT_RT) */
>
> With this code, you get silent side-effects of enabling PPC_CELLEB
> along with another platform.
>
> Maybe instead you should change the hpte_need_flush() to always flush
> when running on the celleb platform and PREEMPT_RT is enabled.
I think it's wrong either way.... Maybe we can make it a variable and
measure how much we can reasonably do in a given time frame at
boot ? :-) Since it depends wether there's an hypervisor etc...
Ben.
prev parent reply other threads:[~2007-05-15 7:23 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-14 6:22 [patch 0/4] powerpc 2.6.21-rt1: fix build a breakage and some minor issues Tsutomu OWA
2007-05-14 6:26 ` [patch 1/4] powerpc 2.6.21-rt1: fix a build breakage by adding __raw_*_relax() macros Tsutomu OWA
2007-05-14 6:28 ` [patch 2/4] powerpc 2.6.21-rt1: convert spinlocks to raw ones for Celleb Tsutomu OWA
2007-05-14 6:29 ` [patch 3/4] powerpc 2.6.21-rt1: add a need_resched_delayed() check Tsutomu OWA
2007-05-14 6:30 ` [patch 0/4] powerpc 2.6.21-rt1: reduce scheduling latency by changing tlb flush size Tsutomu OWA
2007-05-14 6:38 ` [patch 4/4] " Tsutomu OWA
2007-05-14 6:51 ` Thomas Gleixner
2007-05-14 7:28 ` Tsutomu OWA
2007-05-14 14:40 ` Arnd Bergmann
2007-05-15 4:12 ` Tsutomu OWA
2007-05-15 7:34 ` Benjamin Herrenschmidt
2007-05-15 6:27 ` Tsutomu OWA
2007-05-15 7:38 ` Benjamin Herrenschmidt
2007-05-15 8:08 ` Tsutomu OWA
2007-05-15 8:40 ` Benjamin Herrenschmidt
2007-05-15 7:23 ` Benjamin Herrenschmidt [this message]
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