From: Will Deacon <will.deacon@arm.com>
Date: Fri, 21 Feb 2014 16:01:48 +0000 (+0100)
Subject: ARM: 7984/1: prefetch: add prefetchw invocations for barriered atomics
X-Git-Tag: v3.15-rc1~82^2~1^3~20
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c32ffce0f66e5d1d4856254516e24f5ef275cd00;p=pandora-kernel.git

ARM: 7984/1: prefetch: add prefetchw invocations for barriered atomics

After a bunch of benchmarking on the interaction between dmb and pldw,
it turns out that issuing the pldw *after* the dmb instruction can
give modest performance gains (~3% atomic_add_return improvement on a
dual A15).

This patch adds prefetchw invocations to our barriered atomic operations
including cmpxchg, test_and_xxx and futexes.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

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