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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=no 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 003C2C433E0 for ; Fri, 29 May 2020 01:06:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B8B17206E2 for ; Fri, 29 May 2020 01:06:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8B17206E2 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 59A378001A; Thu, 28 May 2020 21:06:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 54A4780010; Thu, 28 May 2020 21:06:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 45F0E8001A; Thu, 28 May 2020 21:06:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0253.hostedemail.com [216.40.44.253]) by kanga.kvack.org (Postfix) with ESMTP id 2BD1380010 for ; Thu, 28 May 2020 21:06:19 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id DBB718245571 for ; Fri, 29 May 2020 01:06:18 +0000 (UTC) X-FDA: 76867965636.26.eyes99_36f50effff014 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin26.hostedemail.com (Postfix) with ESMTP id BDE951804B65C for ; Fri, 29 May 2020 01:06:18 +0000 (UTC) X-HE-Tag: eyes99_36f50effff014 X-Filterd-Recvd-Size: 4718 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Fri, 29 May 2020 01:06:17 +0000 (UTC) IronPort-SDR: smnRjop1lHAdHWZMzs+mxY+EEwMcod1vnGq2+5LVZz+XKTf6ETyASP4rdKOMEpHW8VpftNqqg5 PO9V6IRlmIbg== 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 18:06:15 -0700 IronPort-SDR: wPLApbd6DYzMK/8MiFOPglf1AET+b5PdtqE5iRh/WyKy8aUWq5Ba752pxttb0WOuLgfYHgZjg+ PBN1722ZgSrA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,446,1583222400"; d="scan'208";a="443187384" Received: from shbuild999.sh.intel.com ([10.239.146.107]) by orsmga005.jf.intel.com with ESMTP; 28 May 2020 18:06:11 -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 0/4] make vm_committed_as_batch aware of vm overcommit policy Date: Fri, 29 May 2020 09:06:06 +0800 Message-Id: <1590714370-67182-1-git-send-email-feng.tang@intel.com> X-Mailer: git-send-email 2.7.4 X-Rspamd-Queue-Id: BDE951804B65C 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: When checking a performance change for will-it-scale scalability mmap test [1], we found very high lock contention for spinlock of percpu counter 'vm_committed_as': 94.14% 0.35% [kernel.kallsyms] [k] _raw_spin_lock_irqsave 48.21% _raw_spin_lock_irqsave;percpu_counter_add_batch;__vm_enough_memory;mmap_region;do_mmap; 45.91% _raw_spin_lock_irqsave;percpu_counter_add_batch;__do_munmap; Actually this heavy lock contention is not always necessary. The 'vm_committed_as' needs to be very precise when the strict OVERCOMMIT_NEVER policy is set, which requires a rather small batch number for the percpu counter. So keep 'batch' number unchanged for strict OVERCOMMIT_NEVER policy, and enlarge it for not-so-strict OVERCOMMIT_ALWAYS and OVERCOMMIT_GUESS policies. Benchmark with the same testcase in [1] shows 53% improvement on a 8C/16T desktop, and 2097%(20X) on a 4S/72C/144T server. And for that case, whether it shows improvements depends on if the test mmap size is bigger than the batch number computed. We tested 10+ platforms in 0day (server, desktop and laptop). If we lift it to 64X, 80%+ platforms show improvements, and for 16X lift, 1/3 of the platforms will show improvements. And generally it should help the mmap/unmap usage,as Michal Hocko mentioned: " I believe that there are non-synthetic worklaods which would benefit from a larger batch. E.g. large in memory databases which do large mmaps during startups from multiple threads. " Note: There are some style complain from checkpatch for patch 3, as sysctl handler declaration follows the similar format of sibling functions patch1: a cleanup for /proc/meminfo patch2: a preparation patch which also improve the accuracy of vm_memory_committed patch3: remove the VM_WARN_ONCE for vm_committed_as underflow check patch4: main change This is against today's linux-mm git tree on github. Please help to review, thanks! - Feng ---------------------------------------------------------------- Changelog: v4: * Remove the VM_WARN_ONCE check for vm_committed_as underflow, thanks to Qian Cai for finding and testing the warning v3: * refine commit log and cleanup code, according to comments from Michal Hocko and Matthew Wilcox * change the lift from 16X and 64X after test v2: * add the sysctl handler to cover runtime overcommit policy change, as suggested by Andres Morton * address the accuracy concern of vm_memory_committed() from Andi Kleen Feng Tang (4): proc/meminfo: avoid open coded reading of vm_committed_as mm/util.c: make vm_memory_committed() more accurate mm/util.c: remove the VM_WARN_ONCE for vm_committed_as underflow check mm: adjust vm_committed_as_batch according to vm overcommit policy fs/proc/meminfo.c | 2 +- include/linux/mm.h | 2 ++ include/linux/mman.h | 4 ++++ kernel/sysctl.c | 2 +- mm/mm_init.c | 18 ++++++++++++++---- mm/util.c | 22 +++++++++++++--------- 6 files changed, 35 insertions(+), 15 deletions(-) -- 2.7.4