From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756181Ab0K3TIv (ORCPT ); Tue, 30 Nov 2010 14:08:51 -0500 Received: from smtp110.prem.mail.ac4.yahoo.com ([76.13.13.93]:34479 "HELO smtp110.prem.mail.ac4.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755250Ab0K3TIs (ORCPT ); Tue, 30 Nov 2010 14:08:48 -0500 X-Yahoo-SMTP: _Dag8S.swBC1p4FJKLCXbs8NQzyse1SYSgnAbY0- X-YMail-OSG: kpTlGokVM1kmeUmxDhv3TB_Q55qgZz3kKws5t1trRb78zsf cB3BbAuS2.8Py3W0plVqgpoR9SqmvoiFxXc25eJCxtNJO6C.JjregfVIDJji 52k0XX1HcKM1pLeCz3MgF9SjPoc14ejK8wK3.FHCo.nR1T4p5xH3wW1.nDVm mc.O1ySXRgIHPUi6K3AthUCuKzP8XxGn9nK6mJN8i29rlIq7ndQ7bN14ukJr 3bAI7r8fvwPs3wBdKWSCZNIBb6AvQkqg3r187rzJaZ7hFvuSz9JomTCHhyjT .qK_Z__VZXC30vEI6uG23 X-Yahoo-Newman-Property: ymail-3 Message-Id: <20101130190846.390522413@linux.com> User-Agent: quilt/0.48-1 Date: Tue, 30 Nov 2010 13:07:16 -0600 From: Christoph Lameter To: akpm@linux-foundation.org Cc: Pekka Enberg , Wu Fengguang , Christoph Hellwig Cc: linux-kernel@vger.kernel.org Cc: Eric Dumazet Cc: Mathieu Desnoyers Cc: Tejun Heo Cc: linux-mm@kvack.org Subject: [thisops uV3 09/18] fs: Use this_cpu_xx operations in buffer.c References: <20101130190707.457099608@linux.com> Content-Disposition: inline; filename=this_cpu_buffer Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Optimize various per cpu area operations through the new this cpu operations. These operations avoid address calculations through the use of segment prefixes avoid multiple memory references through RMW instructions etc. Reduces code size: Before: christoph@linux-2.6$ size fs/buffer.o text data bss dec hex filename 19169 80 28 19277 4b4d fs/buffer.o After: christoph@linux-2.6$ size fs/buffer.o text data bss dec hex filename 19138 80 28 19246 4b2e fs/buffer.o Cc: Wu Fengguang Cc: Christoph Hellwig Signed-off-by: Christoph Lameter --- fs/buffer.c | 37 ++++++++++++++++++------------------- 1 file changed, 18 insertions(+), 19 deletions(-) Index: linux-2.6/fs/buffer.c =================================================================== --- linux-2.6.orig/fs/buffer.c 2010-11-30 09:41:30.000000000 -0600 +++ linux-2.6/fs/buffer.c 2010-11-30 09:55:55.000000000 -0600 @@ -1270,12 +1270,10 @@ static inline void check_irqs_on(void) static void bh_lru_install(struct buffer_head *bh) { struct buffer_head *evictee = NULL; - struct bh_lru *lru; check_irqs_on(); bh_lru_lock(); - lru = &__get_cpu_var(bh_lrus); - if (lru->bhs[0] != bh) { + if (__this_cpu_read(bh_lrus.bhs[0]) != bh) { struct buffer_head *bhs[BH_LRU_SIZE]; int in; int out = 0; @@ -1283,7 +1281,8 @@ static void bh_lru_install(struct buffer get_bh(bh); bhs[out++] = bh; for (in = 0; in < BH_LRU_SIZE; in++) { - struct buffer_head *bh2 = lru->bhs[in]; + struct buffer_head *bh2 = + __this_cpu_read(bh_lrus.bhs[in]); if (bh2 == bh) { __brelse(bh2); @@ -1298,7 +1297,7 @@ static void bh_lru_install(struct buffer } while (out < BH_LRU_SIZE) bhs[out++] = NULL; - memcpy(lru->bhs, bhs, sizeof(bhs)); + memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs)); } bh_lru_unlock(); @@ -1313,23 +1312,22 @@ static struct buffer_head * lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size) { struct buffer_head *ret = NULL; - struct bh_lru *lru; unsigned int i; check_irqs_on(); bh_lru_lock(); - lru = &__get_cpu_var(bh_lrus); for (i = 0; i < BH_LRU_SIZE; i++) { - struct buffer_head *bh = lru->bhs[i]; + struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]); if (bh && bh->b_bdev == bdev && bh->b_blocknr == block && bh->b_size == size) { if (i) { while (i) { - lru->bhs[i] = lru->bhs[i - 1]; + __this_cpu_write(bh_lrus.bhs[i], + __this_cpu_read(bh_lrus.bhs[i - 1])); i--; } - lru->bhs[0] = bh; + __this_cpu_write(bh_lrus.bhs[0], bh); } get_bh(bh); ret = bh; @@ -3203,22 +3201,23 @@ static void recalc_bh_state(void) int i; int tot = 0; - if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) + if (__this_cpu_inc_return(bh_accounting.ratelimit) < 4096) return; - __get_cpu_var(bh_accounting).ratelimit = 0; + __this_cpu_write(bh_accounting.ratelimit, 0); for_each_online_cpu(i) tot += per_cpu(bh_accounting, i).nr; buffer_heads_over_limit = (tot > max_buffer_heads); } - + struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) { struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags); if (ret) { INIT_LIST_HEAD(&ret->b_assoc_buffers); - get_cpu_var(bh_accounting).nr++; + preempt_disable(); + __this_cpu_inc(bh_accounting.nr); recalc_bh_state(); - put_cpu_var(bh_accounting); + preempt_enable(); } return ret; } @@ -3228,9 +3227,10 @@ void free_buffer_head(struct buffer_head { BUG_ON(!list_empty(&bh->b_assoc_buffers)); kmem_cache_free(bh_cachep, bh); - get_cpu_var(bh_accounting).nr--; + preempt_disable(); + __this_cpu_dec(bh_accounting.nr); recalc_bh_state(); - put_cpu_var(bh_accounting); + preempt_enable(); } EXPORT_SYMBOL(free_buffer_head); @@ -3243,9 +3243,8 @@ static void buffer_exit_cpu(int cpu) brelse(b->bhs[i]); b->bhs[i] = NULL; } - get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; + this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr); per_cpu(bh_accounting, cpu).nr = 0; - put_cpu_var(bh_accounting); } static int buffer_cpu_notify(struct notifier_block *self,