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From: Marc Zyngier <marc.zyngier@arm.com>
To: Daniel Thompson <daniel.thompson@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jason Cooper <jason@lakedaemon.net>
Cc: Russell King <linux@arm.linux.org.uk>,
	Will Deacon <Will.Deacon@arm.com>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Stephen Boyd <sboyd@codeaurora.org>,
	John Stultz <john.stultz@linaro.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"patches@linaro.org" <patches@linaro.org>,
	"linaro-kernel@lists.linaro.org" <linaro-kernel@lists.linaro.org>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Dirk Behme <dirk.behme@de.bosch.com>,
	Daniel Drake <drake@endlessm.com>,
	Dmitry Pervushin <dpervushin@gmail.com>,
	Tim Sander <tim@krieglstein.org>
Subject: Re: [RESEND PATCH 4.0-rc7 v20 1/6] irqchip: gic: Optimize locking in gic_raise_softirq
Date: Tue, 21 Apr 2015 13:51:07 +0100	[thread overview]
Message-ID: <553647BB.6030408@arm.com> (raw)
In-Reply-To: <1428659511-9590-2-git-send-email-daniel.thompson@linaro.org>

On 10/04/15 10:51, Daniel Thompson wrote:
> Currently gic_raise_softirq() is locked using upon irq_controller_lock.
> This lock is primarily used to make register read-modify-write sequences
> atomic but gic_raise_softirq() uses it instead to ensure that the
> big.LITTLE migration logic can figure out when it is safe to migrate
> interrupts between physical cores.
> 
> This is sub-optimal in closely related ways:
> 
> 1. No locking at all is required on systems where the b.L switcher is
>    not configured.
> 
> 2. Finer grain locking can be used on systems where the b.L switcher is
>    present.
> 
> This patch resolves both of the above by introducing a separate finer
> grain lock and providing conditionally compiled inlines to lock/unlock
> it.
> 
> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Jason Cooper <jason@lakedaemon.net>
> Cc: Russell King <linux@arm.linux.org.uk>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>

Looks good to me.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Jazz is not dead. It just smells funny...

  reply	other threads:[~2015-04-21 12:51 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-24 16:53 [PATCH 4.0-rc5 v19 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-03-24 16:53 ` [PATCH 4.0-rc5 v19 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-03-24 16:53 ` [PATCH 4.0-rc5 v19 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-03-24 16:53 ` [PATCH 4.0-rc5 v19 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-03-24 16:53 ` [PATCH 4.0-rc5 v19 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-03-24 16:53 ` [PATCH 4.0-rc5 v19 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-03-24 16:53 ` [PATCH 4.0-rc5 v19 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-04-07 15:37 ` [RESEND PATCH 4.0-rc5 v19 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-04-07 15:37   ` [RESEND PATCH 4.0-rc5 v19 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-04-07 15:37   ` [RESEND PATCH 4.0-rc5 v19 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-04-07 15:38   ` [RESEND PATCH 4.0-rc5 v19 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-04-07 15:38   ` [RESEND PATCH 4.0-rc5 v19 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-04-07 15:38   ` [RESEND PATCH 4.0-rc5 v19 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-04-07 16:19     ` Steven Rostedt
2015-04-07 16:37       ` Borislav Petkov
2015-04-07 16:43         ` Steven Rostedt
2015-04-08 12:08           ` Daniel Thompson
2015-04-07 15:38   ` [RESEND PATCH 4.0-rc5 v19 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-04-10  9:51 ` [RESEND PATCH 4.0-rc7 v20 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-04-10  9:51   ` [RESEND PATCH 4.0-rc7 v20 1/6] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2015-04-21 12:51     ` Marc Zyngier [this message]
2015-04-10  9:51   ` [RESEND PATCH 4.0-rc7 v20 2/6] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2015-04-21 12:54     ` Marc Zyngier
2015-04-10  9:51   ` [RESEND PATCH 4.0-rc7 v20 3/6] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2015-04-21 13:45     ` Marc Zyngier
2015-04-21 21:03       ` Daniel Thompson
2015-04-22  9:15         ` Marc Zyngier
2015-04-22 12:45           ` Daniel Thompson
2015-04-22 12:57             ` Marc Zyngier
2015-04-22 15:40               ` Daniel Thompson
2015-04-21 14:50     ` Mark Rutland
2015-04-21 21:15       ` Daniel Thompson
2015-04-22 10:38         ` Mark Rutland
2015-07-02 13:31           ` Daniel Thompson
2015-04-10  9:51   ` [RESEND PATCH 4.0-rc7 v20 4/6] printk: Simple implementation for NMI backtracing Daniel Thompson
2015-04-10  9:51   ` [RESEND PATCH 4.0-rc7 v20 5/6] x86/nmi: Use common printk functions Daniel Thompson
2015-04-10  9:51   ` [RESEND PATCH 4.0-rc7 v20 6/6] ARM: Add support for on-demand backtrace of other CPUs Daniel Thompson
2015-04-10 10:47   ` [RESEND PATCH 4.0-rc7 v20 0/6] irq/arm: Implement arch_trigger_all_cpu_backtrace Daniel Thompson
2015-04-21 12:46   ` Thomas Gleixner
2015-04-21 13:08     ` Marc Zyngier

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