43 lines
1.5 KiB
Diff
43 lines
1.5 KiB
Diff
From c7340d6ce152aab9e62cf25f04f9dfae706bb905 Mon Sep 17 00:00:00 2001
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From: Yong Zhang <yong.zhang at windriver.com>
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Date: Thu, 29 Jan 2015 12:56:18 -0600
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Subject: [PATCH] ARM: cmpxchg: define __HAVE_ARCH_CMPXCHG for armv6 and
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later
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.0/patches-4.0.5-rt3.tar.xz
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Both pi_stress and sigwaittest in rt-test show performance gain with
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__HAVE_ARCH_CMPXCHG. Testing result on coretile_express_a9x4:
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pi_stress -p 99 --duration=300 (on linux-3.4-rc5; bigger is better)
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vanilla: Total inversion performed: 5493381
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patched: Total inversion performed: 5621746
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sigwaittest -p 99 -l 100000 (on linux-3.4-rc5-rt6; less is better)
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3.4-rc5-rt6: Min 24, Cur 27, Avg 30, Max 98
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patched: Min 19, Cur 21, Avg 23, Max 96
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Signed-off-by: Yong Zhang <yong.zhang0 at gmail.com>
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Cc: Russell King <rmk+kernel at arm.linux.org.uk>
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Cc: Nicolas Pitre <nico at linaro.org>
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Cc: Will Deacon <will.deacon at arm.com>
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Cc: Catalin Marinas <catalin.marinas at arm.com>
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Cc: Thomas Gleixner <tglx at linutronix.de>
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Cc: linux-arm-kernel at lists.infradead.org
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Cc: stable-rt@vger.kernel.org
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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arch/arm/include/asm/cmpxchg.h | 2 ++
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1 file changed, 2 insertions(+)
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--- a/arch/arm/include/asm/cmpxchg.h
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+++ b/arch/arm/include/asm/cmpxchg.h
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@@ -129,6 +129,8 @@ static inline unsigned long __xchg(unsig
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#else /* min ARCH >= ARMv6 */
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+#define __HAVE_ARCH_CMPXCHG 1
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+
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extern void __bad_cmpxchg(volatile void *ptr, int size);
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/*
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