From: Ingo Molnar <mingo@elte.hu>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>,
Marc Zyngier <Marc.Zyngier@arm.com>,
Frank Rowand <frank.rowand@am.sony.com>,
Oleg Nesterov <oleg@redhat.com>,
linux-kernel@vger.kernel.org, Yong Zhang <yong.zhang0@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM
Date: Thu, 26 May 2011 14:50:07 +0200 [thread overview]
Message-ID: <20110526125007.GA27083@elte.hu> (raw)
In-Reply-To: <20110526123137.GG24876@n2100.arm.linux.org.uk>
* Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> On Thu, May 26, 2011 at 02:26:23PM +0200, Ingo Molnar wrote:
> >
> > * Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > Sort this by reverting to the old behaviour for this situation
> > > and perform a full remote wake-up.
> >
> > Btw., ARM should consider switching most of its subarchitectures
> > to !__ARCH_WANT_INTERRUPTS_ON_CTXSW - enabling irqs during
> > context switches is silly and now expensive as well.
>
> Not going to happen. The reason we do it is because most of the
> CPUs have to (slowly) flush their caches during switch_mm(), and to
> have IRQs off over the cache flush means that we lose IRQs.
How much time does that take on contemporary ARM hardware, typically
(and worst-case)?
Thanks,
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: mingo@elte.hu (Ingo Molnar)
To: linux-arm-kernel@lists.infradead.org
Subject: [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM
Date: Thu, 26 May 2011 14:50:07 +0200 [thread overview]
Message-ID: <20110526125007.GA27083@elte.hu> (raw)
In-Reply-To: <20110526123137.GG24876@n2100.arm.linux.org.uk>
* Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> On Thu, May 26, 2011 at 02:26:23PM +0200, Ingo Molnar wrote:
> >
> > * Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > > Sort this by reverting to the old behaviour for this situation
> > > and perform a full remote wake-up.
> >
> > Btw., ARM should consider switching most of its subarchitectures
> > to !__ARCH_WANT_INTERRUPTS_ON_CTXSW - enabling irqs during
> > context switches is silly and now expensive as well.
>
> Not going to happen. The reason we do it is because most of the
> CPUs have to (slowly) flush their caches during switch_mm(), and to
> have IRQs off over the cache flush means that we lose IRQs.
How much time does that take on contemporary ARM hardware, typically
(and worst-case)?
Thanks,
Ingo
next prev parent reply other threads:[~2011-05-26 12:50 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-24 18:13 [BUG] "sched: Remove rq->lock from the first half of ttwu()" locks up on ARM Marc Zyngier
2011-05-24 18:13 ` Marc Zyngier
2011-05-24 21:32 ` Peter Zijlstra
2011-05-24 21:32 ` Peter Zijlstra
2011-05-24 21:39 ` Ingo Molnar
2011-05-24 21:39 ` Ingo Molnar
2011-05-25 12:23 ` Marc Zyngier
2011-05-25 12:23 ` Marc Zyngier
2011-05-25 17:08 ` Peter Zijlstra
2011-05-25 17:08 ` Peter Zijlstra
2011-05-25 21:15 ` Peter Zijlstra
2011-05-25 21:15 ` Peter Zijlstra
2011-05-26 7:29 ` Yong Zhang
2011-05-26 7:29 ` Yong Zhang
2011-05-26 10:32 ` Peter Zijlstra
2011-05-26 10:32 ` Peter Zijlstra
2011-05-26 11:02 ` Marc Zyngier
2011-05-26 11:02 ` Marc Zyngier
2011-05-26 11:32 ` Peter Zijlstra
2011-05-26 11:32 ` Peter Zijlstra
2011-05-26 12:21 ` Peter Zijlstra
2011-05-26 12:21 ` Peter Zijlstra
2011-05-26 12:26 ` Ingo Molnar
2011-05-26 12:26 ` Ingo Molnar
2011-05-26 12:31 ` Russell King - ARM Linux
2011-05-26 12:31 ` Russell King - ARM Linux
2011-05-26 12:37 ` Peter Zijlstra
2011-05-26 12:37 ` Peter Zijlstra
2011-05-26 12:50 ` Ingo Molnar [this message]
2011-05-26 12:50 ` Ingo Molnar
2011-05-26 13:36 ` Russell King - ARM Linux
2011-05-26 13:36 ` Russell King - ARM Linux
2011-05-26 14:45 ` Catalin Marinas
2011-05-26 14:45 ` Catalin Marinas
2011-05-27 12:06 ` Ingo Molnar
2011-05-27 12:06 ` Ingo Molnar
2011-05-27 17:55 ` Russell King - ARM Linux
2011-05-27 17:55 ` Russell King - ARM Linux
2011-05-27 19:41 ` Nicolas Pitre
2011-05-27 19:41 ` Nicolas Pitre
2011-05-27 20:52 ` Russell King - ARM Linux
2011-05-27 20:52 ` Russell King - ARM Linux
2011-05-28 13:13 ` Peter Zijlstra
2011-05-28 13:13 ` Peter Zijlstra
2011-05-31 11:08 ` Michal Simek
2011-05-31 11:08 ` Michal Simek
2011-05-31 13:22 ` Peter Zijlstra
2011-05-31 13:22 ` Peter Zijlstra
2011-05-31 13:37 ` Michal Simek
2011-05-31 13:37 ` Michal Simek
2011-05-31 13:52 ` Peter Zijlstra
2011-05-31 13:52 ` Peter Zijlstra
2011-05-31 14:08 ` Michal Simek
2011-05-31 14:08 ` Michal Simek
2011-05-31 14:29 ` Peter Zijlstra
2011-05-31 14:29 ` Peter Zijlstra
2011-05-29 10:21 ` Catalin Marinas
2011-05-29 10:21 ` Catalin Marinas
2011-05-29 10:26 ` Russell King - ARM Linux
2011-05-29 10:26 ` Russell King - ARM Linux
2011-05-29 12:01 ` Catalin Marinas
2011-05-29 12:01 ` Catalin Marinas
2011-05-29 13:19 ` Russell King - ARM Linux
2011-05-29 13:19 ` Russell King - ARM Linux
2011-05-29 21:21 ` Catalin Marinas
2011-05-29 21:21 ` Catalin Marinas
2011-05-29 9:51 ` Catalin Marinas
2011-05-29 9:51 ` Catalin Marinas
2011-06-06 10:29 ` Pavel Machek
2011-06-06 10:29 ` Pavel Machek
2011-05-26 14:56 ` Marc Zyngier
2011-05-26 14:56 ` Marc Zyngier
2011-05-26 15:45 ` Oleg Nesterov
2011-05-26 15:45 ` Oleg Nesterov
2011-05-26 15:59 ` Peter Zijlstra
2011-05-26 15:59 ` Peter Zijlstra
2011-05-26 16:09 ` Peter Zijlstra
2011-05-26 16:09 ` Peter Zijlstra
2011-05-26 16:20 ` Marc Zyngier
2011-05-26 16:20 ` Marc Zyngier
2011-05-26 16:32 ` Peter Zijlstra
2011-05-26 16:32 ` Peter Zijlstra
2011-05-27 8:01 ` Marc Zyngier
2011-05-27 8:01 ` Marc Zyngier
2011-05-26 16:22 ` Marc Zyngier
2011-05-26 16:22 ` Marc Zyngier
2011-05-26 17:04 ` Oleg Nesterov
2011-05-26 17:04 ` Oleg Nesterov
2011-05-26 17:17 ` Peter Zijlstra
2011-05-26 17:17 ` Peter Zijlstra
2011-05-26 17:23 ` Peter Zijlstra
2011-05-26 17:23 ` Peter Zijlstra
2011-05-26 17:49 ` Oleg Nesterov
2011-05-26 17:49 ` Oleg Nesterov
2011-05-27 7:01 ` Yong Zhang
2011-05-27 7:01 ` Yong Zhang
2011-05-27 15:23 ` Santosh Shilimkar
2011-05-27 15:23 ` Santosh Shilimkar
2011-05-27 15:29 ` Marc Zyngier
2011-05-27 15:29 ` Marc Zyngier
2011-05-27 15:30 ` Santosh Shilimkar
2011-05-27 15:30 ` Santosh Shilimkar
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