From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 25 Jul 2002 11:10:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 25 Jul 2002 11:10:39 -0400 Received: from e31.co.us.ibm.com ([32.97.110.129]:5073 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id ; Thu, 25 Jul 2002 11:10:37 -0400 Date: Thu, 25 Jul 2002 20:45:12 +0530 From: Ravikiran G Thirumalai To: torvalds@transmeta.com Cc: linux-kernel@vger.kernel.org, trivial@rustcorp.com.au Subject: Patch 2.5.25: Ensure xtime_lock and timerlist_lock are on difft cachelines Message-ID: <20020725204512.E3594@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I've noticed that xtime_lock and timerlist_lock ends up on the same cacheline all the time (atleaset on x86). Not a good thing for loads with high xxx_timer and do_gettimeofday counts I guess (networking etc). Here's a 2.5.25 objdump: c0302780 g O .data 00000004 time_freq c0302784 g O .data 00000004 timerlist_lock c0302788 g O .data 00000004 tqueue_lock c030278c g O .data 00000004 xtime_lock c0302790 l O .data 00000004 count.3 c0302794 l O .data 00000004 uidhash_lock c0302798 g O .data 00000018 root_user Here's a trivial 2.5.28 based fix. -Kiran diff -ruN -X dontdiff linux-2.5.28/kernel/timer.c align_locks/kernel/timer.c --- linux-2.5.28/kernel/timer.c Thu Jul 25 02:33:23 2002 +++ align_locks/kernel/timer.c Thu Jul 25 18:17:46 2002 @@ -169,7 +169,7 @@ } /* Initialize both explicitly - let's try to have them in the same cache line */ -spinlock_t timerlist_lock = SPIN_LOCK_UNLOCKED; +spinlock_t timerlist_lock ____cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED; #ifdef CONFIG_SMP volatile struct timer_list * volatile running_timer; @@ -327,7 +327,7 @@ spin_unlock_irq(&timerlist_lock); } -spinlock_t tqueue_lock = SPIN_LOCK_UNLOCKED; +spinlock_t tqueue_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED; void tqueue_bh(void) { @@ -633,7 +633,7 @@ * This read-write spinlock protects us from races in SMP while * playing with xtime and avenrun. */ -rwlock_t xtime_lock = RW_LOCK_UNLOCKED; +rwlock_t xtime_lock __cacheline_aligned_in_smp = RW_LOCK_UNLOCKED; unsigned long last_time_offset; static inline void update_times(void)