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From: Catalin Marinas <catalin.marinas@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: James Hogan <james.hogan@imgtec.com>,
	"mingo@kernel.org" <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"luto@amacapital.net" <luto@amacapital.net>,
	"nicolas.pitre@linaro.org" <nicolas.pitre@linaro.org>,
	"daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>,
	"umgwanakikbuti@gmail.com" <umgwanakikbuti@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Will Deacon <Will.Deacon@arm.com>,
	ARM Kernel List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC][PATCH 6/8] sched,idle: Avoid spurious wakeup IPIs
Date: Fri, 9 May 2014 15:57:45 +0100	[thread overview]
Message-ID: <20140509145745.GI7950@arm.com> (raw)
In-Reply-To: <20140509145002.GW2844@laptop.programming.kicks-ass.net>

On Fri, May 09, 2014 at 03:50:02PM +0100, Peter Zijlstra wrote:
> On Fri, May 09, 2014 at 03:40:34PM +0100, Catalin Marinas wrote:
> 
> > I wonder why we still need TIF_POLLING_NRFLAG for arm64. It was on arm
> > until commit 16a8016372c42c7628eb (sanitize tsk_is_polling()). On arm64
> > we use wfi for idle or a firmware call but in both cases the assumption
> > is that we need an interrupt for waking up.
> > 
> > So I think we should remove this macro for arm64.
> 
> Does ARM64 support idle=poll? If so, you could keep it for that,
> otherwise it does indeed appear to be pointless.

We don't support idle=poll either.

> As to 32bit ARM, are there SMP chips which do not have WFI?

No. WFI is even used for the secondary booting protocol (we need to send
an IPI to get them going).

-- 
Catalin

  reply	other threads:[~2014-05-09 14:58 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-11 13:42 [RFC][PATCH 0/8] sched,idle: need resched polling rework Peter Zijlstra
2014-04-11 13:42 ` [RFC][PATCH 1/8] sched,idle,alpha: Switch from TS_POLLING to TIF_POLLING_NRFLAG Peter Zijlstra
2014-04-11 14:38   ` Richard Henderson
2014-04-11 13:42 ` [RFC][PATCH 2/8] sched,idle,tile: " Peter Zijlstra
2014-04-11 15:15   ` Chris Metcalf
2014-04-11 15:30     ` Peter Zijlstra
2014-04-11 13:42 ` [RFC][PATCH 3/8] sched,idle,ia64: " Peter Zijlstra
2014-04-11 13:42 ` [RFC][PATCH 4/8] sched,idle,x86: " Peter Zijlstra
2014-04-11 13:42 ` [RFC][PATCH 5/8] sched,idle: Remove TS_POLLING support Peter Zijlstra
2014-04-11 13:42 ` [RFC][PATCH 6/8] sched,idle: Avoid spurious wakeup IPIs Peter Zijlstra
2014-04-13 21:41   ` Nicolas Pitre
2014-05-09 13:37   ` James Hogan
2014-05-09 14:15     ` Peter Zijlstra
2014-05-09 14:40       ` Catalin Marinas
2014-05-09 14:50         ` Peter Zijlstra
2014-05-09 14:57           ` Catalin Marinas [this message]
2014-05-09 17:02             ` Peter Zijlstra
2014-05-09 17:06               ` Peter Zijlstra
2014-05-09 17:09                 ` Catalin Marinas
2014-05-09 17:20                   ` Peter Zijlstra
2014-05-19 12:54                 ` [tip:sched/arch] arm64: Remove TIF_POLLING_NRFLAG tip-bot for Peter Zijlstra
2014-05-22 12:26                 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2014-05-09 14:51       ` [RFC][PATCH 6/8] sched,idle: Avoid spurious wakeup IPIs James Hogan
2014-05-15  9:17         ` James Hogan
2014-05-19 12:54         ` [tip:sched/arch] metag: Remove TIF_POLLING_NRFLAG tip-bot for James Hogan
2014-05-22 12:26         ` [tip:sched/core] " tip-bot for James Hogan
2014-04-11 13:42 ` [RFC][PATCH 7/8] sched,idle: Delay clearing the polling bit Peter Zijlstra
2014-04-13 21:51   ` Nicolas Pitre
2014-04-11 13:42 ` [RFC][PATCH 8/8] sched,idle: Reflow cpuidle_idle_call() Peter Zijlstra
2014-04-13 21:36   ` Nicolas Pitre
2014-04-14  8:59     ` Peter Zijlstra
2014-04-14  9:25       ` Peter Zijlstra
2014-04-14 13:55         ` Nicolas Pitre
2014-04-11 15:00 ` [RFC][PATCH 0/8] sched,idle: need resched polling rework Andy Lutomirski
2014-04-11 15:14   ` Peter Zijlstra
2014-05-22 12:58   ` Peter Zijlstra
2014-05-22 13:09     ` Peter Zijlstra
2014-05-29  0:01       ` Andy Lutomirski
2014-05-29  6:48         ` Peter Zijlstra
2014-06-03  6:40           ` Andy Lutomirski
2014-06-03  6:51             ` Peter Zijlstra
2014-06-03 10:43             ` Peter Zijlstra
2014-06-03 14:02               ` Peter Zijlstra
2014-06-03 16:05                 ` Andy Lutomirski
2014-06-03 16:19                   ` Peter Zijlstra
2014-06-03 16:52                     ` Andy Lutomirski
2014-06-03 17:00                       ` Peter Zijlstra
2014-06-03 18:28                         ` Peter Zijlstra
2014-06-03 18:44                           ` Andy Lutomirski
2014-06-03 20:07                             ` Andy Lutomirski
2014-04-12  8:35 ` Mike Galbraith

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