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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 F0074CA9EAD for ; Sun, 20 Oct 2019 22:44:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9FDC0218BA for ; Sun, 20 Oct 2019 22:44:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9FDC0218BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D96288E0005; Sun, 20 Oct 2019 18:44:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AE1CD8E0003; Sun, 20 Oct 2019 18:44:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 793118E0005; Sun, 20 Oct 2019 18:44:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id 6A3AE8E0003 for ; Sun, 20 Oct 2019 18:44:12 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with SMTP id EBE275838 for ; Sun, 20 Oct 2019 22:44:11 +0000 (UTC) X-FDA: 76065642702.14.grass64_41b5352e98e3e X-HE-Tag: grass64_41b5352e98e3e X-Filterd-Recvd-Size: 1747 Received: from gentwo.org (gentwo.org [3.19.106.255]) by imf50.hostedemail.com (Postfix) with ESMTP for ; Sun, 20 Oct 2019 22:44:11 +0000 (UTC) Received: by gentwo.org (Postfix, from userid 1002) id D2EDD3EEDA; Sun, 20 Oct 2019 22:44:10 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id D08A23EB25; Sun, 20 Oct 2019 22:44:10 +0000 (UTC) Date: Sun, 20 Oct 2019 22:44:10 +0000 (UTC) From: Christopher Lameter X-X-Sender: cl@www.lameter.com To: Roman Gushchin cc: linux-mm@kvack.org, Michal Hocko , Johannes Weiner , linux-kernel@vger.kernel.org, kernel-team@fb.com, Shakeel Butt , Vladimir Davydov , Waiman Long Subject: Re: [PATCH 02/16] mm: vmstat: use s32 for vm_node_stat_diff in struct per_cpu_nodestat In-Reply-To: <20191018002820.307763-3-guro@fb.com> Message-ID: References: <20191018002820.307763-1-guro@fb.com> <20191018002820.307763-3-guro@fb.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Bogosity: Ham, tests=bogofilter, spamicity=0.000006, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 17 Oct 2019, Roman Gushchin wrote: > But if some counters are in bytes (and the next commit in the series > will convert slab counters to bytes), it's not gonna work: > value in bytes can easily exceed s8 without exceeding the threshold > converted to bytes. So to avoid overfilling per-cpu caches and breaking > vmstats correctness, let's use s32 instead. This quardruples the cache footprint of the counters and likely has some influence on performance.