From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751452AbWCSI5y (ORCPT ); Sun, 19 Mar 2006 03:57:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751459AbWCSI5y (ORCPT ); Sun, 19 Mar 2006 03:57:54 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:12929 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1751452AbWCSI5x (ORCPT ); Sun, 19 Mar 2006 03:57:53 -0500 From: Paul Jackson To: Andrew Morton Cc: Simon.Derr@bull.net, Paul Jackson , linux-kernel@vger.kernel.org Date: Sun, 19 Mar 2006 00:57:49 -0800 Message-Id: <20060319085749.18843.28770.sendpatchset@jackhammer.engr.sgi.com> Subject: [PATCH] Cpuset: don't need to mark cpuset_mems_generation atomic Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org From: Paul Jackson Drop the atomic_t marking on the cpuset static global cpuset_mems_generation. Since all access to it is guarded by the global manage_mutex, there is no need for further serialization of this value. Signed-off-by: Paul Jackson --- kernel/cpuset.c | 19 +++++++++++-------- 1 files changed, 11 insertions(+), 8 deletions(-) --- 2.6.16-rc6-mm2.orig/kernel/cpuset.c 2006-03-18 21:27:46.629134245 -0800 +++ 2.6.16-rc6-mm2/kernel/cpuset.c 2006-03-18 21:34:04.426490767 -0800 @@ -149,7 +149,7 @@ static inline int is_spread_slab(const s } /* - * Increment this atomic integer everytime any cpuset changes its + * Increment this integer everytime any cpuset changes its * mems_allowed value. Users of cpusets can track this generation * number, and avoid having to lock and reload mems_allowed unless * the cpuset they're using changes generation. @@ -163,8 +163,11 @@ static inline int is_spread_slab(const s * on every visit to __alloc_pages(), to efficiently check whether * its current->cpuset->mems_allowed has changed, requiring an update * of its current->mems_allowed. + * + * Since cpuset_mems_generation is guarded by manage_mutex, + * there is no need to mark it atomic. */ -static atomic_t cpuset_mems_generation = ATOMIC_INIT(1); +static int cpuset_mems_generation; static struct cpuset top_cpuset = { .flags = ((1 << CS_CPU_EXCLUSIVE) | (1 << CS_MEM_EXCLUSIVE)), @@ -877,7 +880,7 @@ static int update_nodemask(struct cpuset mutex_lock(&callback_mutex); cs->mems_allowed = trialcs.mems_allowed; - cs->mems_generation = atomic_inc_return(&cpuset_mems_generation); + cs->mems_generation = cpuset_mems_generation++; mutex_unlock(&callback_mutex); set_cpuset_being_rebound(cs); /* causes mpol_copy() rebind */ @@ -1270,11 +1273,11 @@ static ssize_t cpuset_common_file_write( break; case FILE_SPREAD_PAGE: retval = update_flag(CS_SPREAD_PAGE, cs, buffer); - cs->mems_generation = atomic_inc_return(&cpuset_mems_generation); + cs->mems_generation = cpuset_mems_generation++; break; case FILE_SPREAD_SLAB: retval = update_flag(CS_SPREAD_SLAB, cs, buffer); - cs->mems_generation = atomic_inc_return(&cpuset_mems_generation); + cs->mems_generation = cpuset_mems_generation++; break; case FILE_TASKLIST: retval = attach_task(cs, buffer, &pathbuf); @@ -1823,7 +1826,7 @@ static long cpuset_create(struct cpuset atomic_set(&cs->count, 0); INIT_LIST_HEAD(&cs->sibling); INIT_LIST_HEAD(&cs->children); - cs->mems_generation = atomic_inc_return(&cpuset_mems_generation); + cs->mems_generation = cpuset_mems_generation++; fmeter_init(&cs->fmeter); cs->parent = parent; @@ -1913,7 +1916,7 @@ int __init cpuset_init_early(void) struct task_struct *tsk = current; tsk->cpuset = &top_cpuset; - tsk->cpuset->mems_generation = atomic_inc_return(&cpuset_mems_generation); + tsk->cpuset->mems_generation = cpuset_mems_generation++; return 0; } @@ -1932,7 +1935,7 @@ int __init cpuset_init(void) top_cpuset.mems_allowed = NODE_MASK_ALL; fmeter_init(&top_cpuset.fmeter); - top_cpuset.mems_generation = atomic_inc_return(&cpuset_mems_generation); + top_cpuset.mems_generation = cpuset_mems_generation++; init_task.cpuset = &top_cpuset; -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.650.933.1373