linux-kernel - Re: [RFC][PATCH 6/8] sched,idle: Avoid spurious wakeup IPIs

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Message-ID: <20140509170649.GG13658@twins.programming.kicks-ass.net>
Date:	Fri, 9 May 2014 19:06:49 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	James Hogan <james.hogan@...tec.com>,
	"mingo@...nel.org" <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"luto@...capital.net" <luto@...capital.net>,
	"nicolas.pitre@...aro.org" <nicolas.pitre@...aro.org>,
	"daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
	"umgwanakikbuti@...il.com" <umgwanakikbuti@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Will Deacon <Will.Deacon@....com>,
	ARM Kernel List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC][PATCH 6/8] sched,idle: Avoid spurious wakeup IPIs

On Fri, May 09, 2014 at 07:02:34PM +0200, Peter Zijlstra wrote:
> OK, so I'll queue a patch removing TIF_POLLING_NRFLAG for arm64.


---
Subject: arm64: Remove TIF_POLLING_NRFLAG
From: Peter Zijlstra <peterz@...radead.org>
Date: Fri May  9 19:04:00 CEST 2014

The only idle method for arm64 is WFI and it therefore
unconditionally requires the reschedule interrupt when idle.

Suggested-by: Catalin Marinas <catalin.marinas@....com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
---
 arch/arm64/include/asm/thread_info.h |    2 --
 1 file changed, 2 deletions(-)

--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -95,13 +95,11 @@ static inline struct thread_info *curren
  *  TIF_NEED_RESCHED	- rescheduling necessary
  *  TIF_NOTIFY_RESUME	- callback before returning to user
  *  TIF_USEDFPU		- FPU was used by this task this quantum (SMP)
- *  TIF_POLLING_NRFLAG	- true if poll_idle() is polling TIF_NEED_RESCHED
  */
 #define TIF_SIGPENDING		0
 #define TIF_NEED_RESCHED	1
 #define TIF_NOTIFY_RESUME	2	/* callback before returning to user */
 #define TIF_SYSCALL_TRACE	8
-#define TIF_POLLING_NRFLAG	16
 #define TIF_MEMDIE		18	/* is terminating due to OOM killer */
 #define TIF_FREEZE		19
 #define TIF_RESTORE_SIGMASK	20

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