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=-10.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MISSING_HEADERS,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 6E5FAC433E2 for ; Mon, 20 Jul 2020 05:43:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E2961208E4 for ; Mon, 20 Jul 2020 05:43:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E2961208E4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6227D6B0005; Mon, 20 Jul 2020 01:43:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5ADCC6B0007; Mon, 20 Jul 2020 01:43:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 49C466B0008; Mon, 20 Jul 2020 01:43:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0186.hostedemail.com [216.40.44.186]) by kanga.kvack.org (Postfix) with ESMTP id 311086B0005 for ; Mon, 20 Jul 2020 01:43:15 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 75FFC18017890 for ; Mon, 20 Jul 2020 05:43:14 +0000 (UTC) X-FDA: 77057361108.04.news78_31161f326f22 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 0BF658070B10 for ; Mon, 20 Jul 2020 05:42:58 +0000 (UTC) X-HE-Tag: news78_31161f326f22 X-Filterd-Recvd-Size: 3879 Received: from out30-57.freemail.mail.aliyun.com (out30-57.freemail.mail.aliyun.com [115.124.30.57]) by imf16.hostedemail.com (Postfix) with ESMTP for ; Mon, 20 Jul 2020 05:42:55 +0000 (UTC) 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 X-Rspamd-Queue-Id: 0BF658070B10 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000020, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: >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