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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 03E72C433DF for ; Sat, 16 May 2020 06:47:53 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C560920767 for ; Sat, 16 May 2020 06:47:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C560920767 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 784C18E0006; Sat, 16 May 2020 02:47:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 710DC8E0001; Sat, 16 May 2020 02:47:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5FF398E0006; Sat, 16 May 2020 02:47:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0206.hostedemail.com [216.40.44.206]) by kanga.kvack.org (Postfix) with ESMTP id 4681C8E0001 for ; Sat, 16 May 2020 02:47:52 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 0AB3F4DBD for ; Sat, 16 May 2020 06:47:52 +0000 (UTC) X-FDA: 76821651984.01.rub22_61adf39953123 X-HE-Tag: rub22_61adf39953123 X-Filterd-Recvd-Size: 2831 Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Sat, 16 May 2020 06:47:51 +0000 (UTC) IronPort-SDR: uptVPf8HdB/NF/30SEeRN9VXHPF9KsqhLzakQJA8caObrjLNk4Ky0jrS/qMOzgUXR/kHAmlfEE z2fPVD7J7fBQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 May 2020 23:47:50 -0700 IronPort-SDR: MWwpcoNGIUZHitX854RSvMz2jRCeunv+opN/2PqK1ojEY/UnWuiy9zY2VIJndjE/D9Ao/7P6Kf GpYVqLS88WKQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,398,1583222400"; d="scan'208";a="464984933" Received: from shbuild999.sh.intel.com ([10.239.146.107]) by fmsmga005.fm.intel.com with ESMTP; 15 May 2020 23:47:47 -0700 From: Feng Tang To: Andrew Morton , Michal Hocko , Matthew Wilcox , Johannes Weiner , Mel Gorman , Kees Cook , andi.kleen@intel.com, tim.c.chen@intel.com, dave.hansen@intel.com, ying.huang@intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Feng Tang Subject: [PATCH v3 2/3] mm/util.c: make vm_memory_committed() more accurate Date: Sat, 16 May 2020 14:47:39 +0800 Message-Id: <1589611660-89854-3-git-send-email-feng.tang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1589611660-89854-1-git-send-email-feng.tang@intel.com> References: <1589611660-89854-1-git-send-email-feng.tang@intel.com> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: percpu_counter_sum_positive() will provide more accurate info. As with percpu_counter_read_positive(), in worst case the deviation could be 'batch * nr_cpus', which is totalram_pages/256 for now, and will be more when the batch gets enlarged. Its time cost is about 800 nanoseconds on a 2C/4T platform and 2~3 microseconds on a 2S/36C/72T server in normal case, and in worst case where vm_committed_as's spinlock is under severe contention, it costs 30~40 microseconds for the 2S/36C/72T sever, which should be fine for its only two users: /proc/meminfo and HyperV balloon driver's status trace per second. Signed-off-by: Feng Tang --- mm/util.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/util.c b/mm/util.c index 988d11e..3de78e9 100644 --- a/mm/util.c +++ b/mm/util.c @@ -774,7 +774,7 @@ struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; */ unsigned long vm_memory_committed(void) { - return percpu_counter_read_positive(&vm_committed_as); + return percpu_counter_sum_positive(&vm_committed_as); } EXPORT_SYMBOL_GPL(vm_memory_committed); -- 2.7.4