From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 4.4-rc5 v22 1/4] irqchip: gic: Optimize locking in gic_raise_softirq
Date: Thu, 07 Jan 2016 14:31:26 +0000 [thread overview]
Message-ID: <568E76BE.3010702@arm.com> (raw)
In-Reply-To: <1450644757-18734-2-git-send-email-daniel.thompson@linaro.org>
On 20/12/15 20:52, Daniel Thompson wrote:
> Currently gic_raise_softirq() is locked using 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>
Acked-by: Marc Zyngier <marc.zyngier@arm•com>
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2016-01-07 14:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-20 20:52 [PATCH 4.4-rc5 v22 0/4] irq/arm: Use FIQ for NMI backtrace (when possible) Daniel Thompson
2015-12-20 20:52 ` [PATCH 4.4-rc5 v22 1/4] irqchip: gic: Optimize locking in gic_raise_softirq Daniel Thompson
2016-01-07 14:31 ` Marc Zyngier [this message]
2015-12-20 20:52 ` [PATCH 4.4-rc5 v22 2/4] irqchip: gic: Make gic_raise_softirq FIQ-safe Daniel Thompson
2016-01-07 14:35 ` Marc Zyngier
2015-12-20 20:52 ` [PATCH 4.4-rc5 v22 3/4] irqchip: gic: Introduce plumbing for IPI FIQ Daniel Thompson
2016-01-07 17:06 ` Marc Zyngier
2016-01-11 12:02 ` Daniel Thompson
2015-12-20 20:52 ` [PATCH 4.4-rc5 v22 4/4] ARM: Allow IPI_CPU_BACKTRACE to exploit FIQ Daniel Thompson
2015-12-20 22:12 ` kbuild test robot
2016-01-04 10:00 ` Daniel Thompson
2015-12-20 22:52 ` kbuild test robot
2016-01-04 10:05 ` Daniel Thompson
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