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=-9.7 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 AA30CC433E0 for ; Fri, 29 May 2020 01:06:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 78228206E2 for ; Fri, 29 May 2020 01:06:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 78228206E2 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 219A7800B7; Thu, 28 May 2020 21:06:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C83080010; Thu, 28 May 2020 21:06:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0DE98800B7; Thu, 28 May 2020 21:06:24 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0225.hostedemail.com [216.40.44.225]) by kanga.kvack.org (Postfix) with ESMTP id EA80480010 for ; Thu, 28 May 2020 21:06:23 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B0DFA248F for ; Fri, 29 May 2020 01:06:23 +0000 (UTC) X-FDA: 76867965846.21.debt42_37b8a1965e41f Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin21.hostedemail.com (Postfix) with ESMTP id 9BECE180442C0 for ; Fri, 29 May 2020 01:06:23 +0000 (UTC) X-HE-Tag: debt42_37b8a1965e41f X-Filterd-Recvd-Size: 2855 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Fri, 29 May 2020 01:06:22 +0000 (UTC) IronPort-SDR: 20RkHJ7gYymi7pqsRYo2a6bs/fJV6h1W55OdxLWWFpt/HCn3TH5oY0VL4dB1s9cgTeqoMNfnup zEt4kOqIk3Xg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 May 2020 18:06:22 -0700 IronPort-SDR: XQoQpnrS+4xFfOoDQX7PM+NvMtEzY0KYWFvbVJVP6f3UZ1aedMbPSk0G7zOAjoXi/aB9lLwgtq o6qbvV0VJD8w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,446,1583222400"; d="scan'208";a="443187402" Received: from shbuild999.sh.intel.com ([10.239.146.107]) by orsmga005.jf.intel.com with ESMTP; 28 May 2020 18:06:19 -0700 From: Feng Tang To: Andrew Morton , Michal Hocko , Johannes Weiner , Matthew Wilcox , Mel Gorman , Kees Cook , Qian Cai , 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 v4 2/4] mm/util.c: make vm_memory_committed() more accurate Date: Fri, 29 May 2020 09:06:08 +0800 Message-Id: <1590714370-67182-3-git-send-email-feng.tang@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1590714370-67182-1-git-send-email-feng.tang@intel.com> References: <1590714370-67182-1-git-send-email-feng.tang@intel.com> X-Rspamd-Queue-Id: 9BECE180442C0 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 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 9b3be03..3c7a08c 100644 --- a/mm/util.c +++ b/mm/util.c @@ -790,7 +790,7 @@ 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