From 500c2e1fdbcc2b273bd4c695a9b8ac8196f61614 Mon Sep 17 00:00:00 2001 From: David Daney Date: Thu, 4 Feb 2010 11:31:49 -0800 Subject: MIPS: Optimize spinlocks. The current locking mechanism uses a ll/sc sequence to release a spinlock. This is slower than a wmb() followed by a store to unlock. The branching forward to .subsection 2 on sc failure slows down the contended case. So we get rid of that part too. Since we are now working on naturally aligned u16 values, we can get rid of a masking operation as the LHU already does the right thing. The ANDI are reversed for better scheduling on multi-issue CPUs On a 12 CPU 750MHz Octeon cn5750 this patch improves ipv4 UDP packet forwarding rates from 3.58*10^6 PPS to 3.99*10^6 PPS, or about 11%. Signed-off-by: David Daney To: linux-mips@linux-mips.org Patchwork: http://patchwork.linux-mips.org/patch/937/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/spinlock_types.h | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) (limited to 'arch/mips/include/asm/spinlock_types.h') diff --git a/arch/mips/include/asm/spinlock_types.h b/arch/mips/include/asm/spinlock_types.h index ee197c2f9c98..c52f36013a9d 100644 --- a/arch/mips/include/asm/spinlock_types.h +++ b/arch/mips/include/asm/spinlock_types.h @@ -5,16 +5,28 @@ # error "please don't include this file directly" #endif -typedef struct { +#include + +#include + +typedef union { /* - * bits 0..13: serving_now - * bits 14 : junk data - * bits 15..28: ticket + * bits 0..15 : serving_now + * bits 16..31 : ticket */ - unsigned int lock; + u32 lock; + struct { +#ifdef __BIG_ENDIAN + u16 ticket; + u16 serving_now; +#else + u16 serving_now; + u16 ticket; +#endif + } h; } arch_spinlock_t; -#define __ARCH_SPIN_LOCK_UNLOCKED { 0 } +#define __ARCH_SPIN_LOCK_UNLOCKED { .lock = 0 } typedef struct { volatile unsigned int lock; -- cgit v1.2.3-55-g7522