From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>,
Mats Liljegren <mats.liljegren@enea.com>,
linaro-dev@lists.linaro.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit accessors
Date: Thu, 21 Feb 2013 21:58:50 +0000 [thread overview]
Message-ID: <20130221215850.GC17833@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAFTL4hw1=mKtUadL0WDrydtspOehKuW7jhhzr65vXR2P2zdTWw@mail.gmail.com>
On Thu, Feb 21, 2013 at 10:53:07PM +0100, Frederic Weisbecker wrote:
> That too should be kcpustat_this_cpu_set(), or kcpustat_this_cpu_add()
> FWIW. But we probably don't need the overhead of atomic_add() that
> does a LOCK.
> atomic_set(var, atomic_read(var) + delta) would be better. All we need
You mean atomic64_set() and atomic64_read(). Looking at the generic
version in lib/atomic64.c, atomic64_add() is cheaper for 32-bit arches
because it doesn't involve taking the lock twice.
WARNING: multiple messages have this Message-ID (diff)
From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit accessors
Date: Thu, 21 Feb 2013 21:58:50 +0000 [thread overview]
Message-ID: <20130221215850.GC17833@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <CAFTL4hw1=mKtUadL0WDrydtspOehKuW7jhhzr65vXR2P2zdTWw@mail.gmail.com>
On Thu, Feb 21, 2013 at 10:53:07PM +0100, Frederic Weisbecker wrote:
> That too should be kcpustat_this_cpu_set(), or kcpustat_this_cpu_add()
> FWIW. But we probably don't need the overhead of atomic_add() that
> does a LOCK.
> atomic_set(var, atomic_read(var) + delta) would be better. All we need
You mean atomic64_set() and atomic64_read(). Looking at the generic
version in lib/atomic64.c, atomic64_add() is cheaper for 32-bit arches
because it doesn't involve taking the lock twice.
next prev parent reply other threads:[~2013-02-21 21:59 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-20 19:41 [RFC/PATCH 0/5] context_tracking: prerequisites for ARM support Kevin Hilman
2013-02-20 19:41 ` Kevin Hilman
2013-02-20 19:41 ` [RFC/PATCH 1/5] context tracking: conditionalize guest support based on CONFIG_KVM Kevin Hilman
2013-02-20 19:41 ` Kevin Hilman
2013-02-22 13:27 ` Frederic Weisbecker
2013-02-22 13:27 ` Frederic Weisbecker
2013-02-26 19:29 ` Kevin Hilman
2013-02-26 19:29 ` Kevin Hilman
2013-02-26 22:13 ` Namhyung Kim
2013-02-26 22:13 ` Namhyung Kim
2013-02-27 14:24 ` Kevin Hilman
2013-02-27 14:24 ` Kevin Hilman
2013-02-27 15:21 ` Frederic Weisbecker
2013-02-27 15:21 ` Frederic Weisbecker
2013-02-20 19:41 ` [RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit accessors Kevin Hilman
2013-02-20 19:41 ` Kevin Hilman
2013-02-21 19:38 ` Kevin Hilman
2013-02-21 19:38 ` Kevin Hilman
2013-02-21 21:53 ` Frederic Weisbecker
2013-02-21 21:53 ` Frederic Weisbecker
2013-02-21 21:54 ` Frederic Weisbecker
2013-02-21 21:54 ` Frederic Weisbecker
2013-02-22 5:57 ` Kevin Hilman
2013-02-22 5:57 ` Kevin Hilman
2013-02-21 21:58 ` Russell King - ARM Linux [this message]
2013-02-21 21:58 ` Russell King - ARM Linux
2013-02-21 22:15 ` Frederic Weisbecker
2013-02-21 22:15 ` Frederic Weisbecker
2013-02-20 19:41 ` [RFC/PATCH 3/5] virt CPU accounting: Kconfig: drop 64-bit requirment Kevin Hilman
2013-02-20 19:41 ` Kevin Hilman
2013-02-20 19:41 ` [RFC/PATCH 4/5] cputime: use do_div() for nsec resolution conversion helpers Kevin Hilman
2013-02-20 19:41 ` Kevin Hilman
2013-02-21 16:24 ` Frederic Weisbecker
2013-02-21 16:24 ` Frederic Weisbecker
2013-02-21 17:58 ` Namhyung Kim
2013-02-21 17:58 ` Namhyung Kim
2013-02-21 19:21 ` Kevin Hilman
2013-02-21 19:21 ` Kevin Hilman
2013-02-26 15:21 ` Frederic Weisbecker
2013-02-26 15:21 ` Frederic Weisbecker
2013-02-20 19:41 ` [RFC/PATCH 5/5] ARM: Kconfig: allow virt CPU accounting Kevin Hilman
2013-02-20 19:41 ` Kevin Hilman
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