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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E78B2C433F5 for ; Sat, 25 Sep 2021 02:59:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C006161151 for ; Sat, 25 Sep 2021 02:59:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347521AbhIYDBA (ORCPT ); Fri, 24 Sep 2021 23:01:00 -0400 Received: from mail-pj1-f41.google.com ([209.85.216.41]:56125 "EHLO mail-pj1-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344612AbhIYDA6 (ORCPT ); Fri, 24 Sep 2021 23:00:58 -0400 Received: by mail-pj1-f41.google.com with SMTP id t20so8277322pju.5 for ; Fri, 24 Sep 2021 19:59:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=bkFXxG1/B7HUImua1LRzQp1SzwFli69GeT83Hh7pQtc=; b=71WQU7T6KHLd8oK9pG4q5owcrZmfKPTl3f0ZiLLs1NfMeEy4mHyIlDojVl0MxorMR5 zU1OAtY9wnR41/vnoYn5SsLx2SyytjpMtUwUtGx5DjSb9/vgcmqRu6uSnY8XBlF7/45l 9Y4K+vYwP5gHVedwryMT4oaQpMdqHv9FuKbX9yZ2Zl8ME4nnPARq6F2NrEBSHF0TZBW+ LUi/xV+f17kF8aNaoOGbRavVaLf6G/3+fHCq4/6fAA5nHYWooLfwB0Z2YECvYB4Um4ES ZRKc0/8Fb6oQ4mxI5gnSPY9v5l+K/RSViDT+qav3r/NW73+QhEY2QYWrNjtAYKqseO6F C5zg== X-Gm-Message-State: AOAM533LZSmvPfEG/Lkhu/ZgSp/6v8koJqlSxvkSF6kUdNyWGqCcj6Ng URB4wV10lguAH9UHxyU+E9AMBpIsqzc= X-Google-Smtp-Source: ABdhPJznLpO94LoGqcoceAdmDSpEVyCdLa0FwpoYqhQp0RUjrNCznPWdF6gKiD72BePdH5wxkYMXBg== X-Received: by 2002:a17:902:bd05:b0:13d:e7cf:3b57 with SMTP id p5-20020a170902bd0500b0013de7cf3b57mr5770602pls.49.1632538764537; Fri, 24 Sep 2021 19:59:24 -0700 (PDT) Received: from ?IPV6:2601:647:4000:d7:92db:e1f6:6924:bfce? ([2601:647:4000:d7:92db:e1f6:6924:bfce]) by smtp.gmail.com with ESMTPSA id p18sm11025042pgk.28.2021.09.24.19.59.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Sep 2021 19:59:23 -0700 (PDT) Message-ID: <81cd7cea-6060-4500-8af3-cd324aef61de@acm.org> Date: Fri, 24 Sep 2021 19:59:22 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH 3/4] block/mq-deadline: Stop using per-CPU counters Content-Language: en-US To: Damien Le Moal , Jens Axboe Cc: "linux-block@vger.kernel.org" , Christoph Hellwig , Jaegeuk Kim , Niklas Cassel , Hannes Reinecke References: <20210923232358.3907118-1-bvanassche@acm.org> <20210923232655.3907383-1-bvanassche@acm.org> <20210923232655.3907383-3-bvanassche@acm.org> From: Bart Van Assche In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 9/24/21 03:58, Damien Le Moal wrote: > On 2021/09/24 8:27, Bart Van Assche wrote: >> -/* I/O statistics for all I/O priorities (enum dd_prio). */ >> -struct io_stats { >> - struct io_stats_per_prio stats[DD_PRIO_COUNT]; >> + uint32_t inserted; >> + uint32_t merged; >> + uint32_t dispatched; >> + atomic_t completed; > > Why not use 64-bits types (regular unsigned long long and atomic64_t) ? Even 64-bit counters can overflow. Using 32-bit counters makes it easier to trigger an overflow of these counters. Thanks, Bart.