From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3BFEFC433E3 for ; Mon, 20 Jul 2020 05:42:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E4EB20758 for ; Mon, 20 Jul 2020 05:42:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726349AbgGTFmv (ORCPT ); Mon, 20 Jul 2020 01:42:51 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:49593 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725845AbgGTFmu (ORCPT ); Mon, 20 Jul 2020 01:42:50 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04427;MF=alex.shi@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0U3CmdbJ_1595223766; Received: from IT-FVFX43SYHV2H.local(mailfrom:alex.shi@linux.alibaba.com fp:SMTPD_---0U3CmdbJ_1595223766) by smtp.aliyun-inc.com(127.0.0.1); Mon, 20 Jul 2020 13:42:47 +0800 Subject: Re: [PATCH] mm/vmstat: don't do count if no needs Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20200720052348.428564-1-alex.shi@linux.alibaba.com> From: Alex Shi Message-ID: <1ef9baa0-9788-5917-2590-a8c3fc593b81@linux.alibaba.com> Date: Mon, 20 Jul 2020 13:42:45 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200720052348.428564-1-alex.shi@linux.alibaba.com> Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 7bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >From 4cb977d34227e4bafa95b8da5e47dbd8b6141d26 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Mon, 20 Jul 2020 11:50:12 +0800 Subject: [PATCH v2] mm/vmstat: don't do count if no needs For couple of vmstat account funcs, the caller usually doesn't check the delta value, if delta == 0, irq or atomic operator is a waste. That's better to be skipped, also add unlikey() since !delta is less happened. Signed-off-by: Alex Shi Cc: Andrew Morton Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/vmstat.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/mm/vmstat.c b/mm/vmstat.c index 3fb23a21f6dd..b02d99dff443 100644 --- a/mm/vmstat.c +++ b/mm/vmstat.c @@ -321,6 +321,9 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item, long x; long t; + if (unlikely(!delta)) + return; + x = delta + __this_cpu_read(*p); t = __this_cpu_read(pcp->stat_threshold); @@ -341,6 +344,9 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item, long x; long t; + if (unlikely(!delta)) + return; + x = delta + __this_cpu_read(*p); t = __this_cpu_read(pcp->stat_threshold); @@ -484,6 +490,9 @@ static inline void mod_zone_state(struct zone *zone, s8 __percpu *p = pcp->vm_stat_diff + item; long o, n, t, z; + if (unlikely(!delta)) + return; + do { z = 0; /* overflow to zone counters */ @@ -518,6 +527,9 @@ static inline void mod_zone_state(struct zone *zone, void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, long delta) { + if (unlikely(!delta)) + return; + mod_zone_state(zone, item, delta, 0); } EXPORT_SYMBOL(mod_zone_page_state); @@ -541,6 +553,9 @@ static inline void mod_node_state(struct pglist_data *pgdat, s8 __percpu *p = pcp->vm_node_stat_diff + item; long o, n, t, z; + if (unlikely(!delta)) + return; + do { z = 0; /* overflow to node counters */ @@ -604,6 +619,9 @@ void mod_zone_page_state(struct zone *zone, enum zone_stat_item item, { unsigned long flags; + if (unlikely(!delta)) + return; + local_irq_save(flags); __mod_zone_page_state(zone, item, delta); local_irq_restore(flags); @@ -647,6 +665,9 @@ void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item, { unsigned long flags; + if (unlikely(!delta)) + return; + local_irq_save(flags); __mod_node_page_state(pgdat, item, delta); local_irq_restore(flags); -- 2.18.4