Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933092Ab1FPVlJ (ORCPT ); Thu, 16 Jun 2011 17:41:09 -0400 Received: from claw.goop.org ([74.207.240.146]:53886 "EHLO claw.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932121Ab1FPVlH (ORCPT ); Thu, 16 Jun 2011 17:41:07 -0400 From: Jeremy Fitzhardinge To: Peter Zijlstra Cc: "H. Peter Anvin" , Ingo Molnar , the arch/x86 maintainers , Linux Kernel Mailing List , Nick Piggin , Jeremy Fitzhardinge Subject: [PATCH 4/7] x86/ticketlock: make large and small ticket versions of spin_lock the same Date: Thu, 16 Jun 2011 14:40:51 -0700 Message-Id: <5877c1a78fd1851e69940f37c124b79633a81fd3.1308259496.git.jeremy.fitzhardinge@citrix.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2381 Lines: 72 From: Jeremy Fitzhardinge Make the bulk of __ticket_spin_lock look identical for large and small number of cpus. Signed-off-by: Jeremy Fitzhardinge --- arch/x86/include/asm/spinlock.h | 23 ++++++++--------------- 1 files changed, 8 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index 0170ba9..1b81809 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -70,19 +70,16 @@ static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock) #if (NR_CPUS < 256) static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { - register union { - struct __raw_tickets tickets; - unsigned short slock; - } inc = { .slock = 1 << TICKET_SHIFT }; + register struct __raw_tickets inc = { .tail = 1 }; asm volatile (LOCK_PREFIX "xaddw %w0, %1\n" - : "+Q" (inc), "+m" (lock->slock) : : "memory", "cc"); + : "+r" (inc), "+m" (lock->tickets) : : "memory", "cc"); for (;;) { - if (inc.tickets.head == inc.tickets.tail) + if (inc.head == inc.tail) goto out; cpu_relax(); - inc.tickets.head = ACCESS_ONCE(lock->tickets.head); + inc.head = ACCESS_ONCE(lock->tickets.head); } out: barrier(); /* make sure nothing creeps before the lock is taken */ } @@ -108,21 +105,17 @@ static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock) #else static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock) { - unsigned inc = 1 << TICKET_SHIFT; - __ticket_t tmp; + register struct __raw_tickets inc = { .tail = 1 }; asm volatile(LOCK_PREFIX "xaddl %0, %1\n\t" - : "+r" (inc), "+m" (lock->slock) + : "+r" (inc), "+m" (lock->tickets) : : "memory", "cc"); - tmp = inc; - inc >>= TICKET_SHIFT; - for (;;) { - if ((__ticket_t)inc == tmp) + if (inc.head == inc.tail) goto out; cpu_relax(); - tmp = ACCESS_ONCE(lock->tickets.head); + inc.head = ACCESS_ONCE(lock->tickets.head); } out: barrier(); /* make sure nothing creeps before the lock is taken */ } -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/