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=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, 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 E85AAC432C3 for ; Thu, 21 Nov 2019 15:56:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C057020714 for ; Thu, 21 Nov 2019 15:56:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="p9f61F2q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727269AbfKUP41 (ORCPT ); Thu, 21 Nov 2019 10:56:27 -0500 Received: from mail-il1-f194.google.com ([209.85.166.194]:34362 "EHLO mail-il1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727209AbfKUP4S (ORCPT ); Thu, 21 Nov 2019 10:56:18 -0500 Received: by mail-il1-f194.google.com with SMTP id p6so3789813ilp.1 for ; Thu, 21 Nov 2019 07:56:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=i6XZTTQSHJKM+KBZCHJbpNr3leYiOU/zZyc4Kt/q1ls=; b=p9f61F2qEE4/QwqhzVpQxRpsxX+tV3SxRebeynsmRfBNHvoMnRcPAeQBMJ4vetLpDz shfSAjNsSLR8/AyOjsQjN2cfgMUQmKjudar8cuqkQT4utDF/Fg0xyKUILGxfQL2m4ykC v2dKDPfCeTVXelv8ErH8wWKv+orr2ysEDzISJsEE+qs4wfsyfactwDmLH8MnBWJzVSmY XCTDegH0huTSluHvW6LcnV5C2iycu99pwuw2Q/YxucMfTo227eo59/I8ZMNVpzMswrI3 2Efr4431bVIGY+4pWPJ+b3TiJoIazJewBg9vmPs5YlVPxg8N869vnJ+tezxnZ3CO4XTi 5d9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=i6XZTTQSHJKM+KBZCHJbpNr3leYiOU/zZyc4Kt/q1ls=; b=VmwZjXQ19DMbc2qUowLBx9oVlwQn5vOBT+oZFr4Vz7/Xp5ydI9dEMcCDXKkcEz//Eh O1Ts33iBv8NrxH2Dj7CpcF0OLfVCq4M1jQsEj/KqicPxmarPas2/39AemOQBP1qmUiPK 9nXKldJRudcroJLuWqpENP7JAtgM8bv5YLtcG0hnLd1151YgDc8t0zjiFl9CLRPZKHT0 9OIHBGY4cPmvQya62jZoeStuzgyyxa1afOr7EG+Bmvmyfxa0129eoNoo3X8mt60l4Pe1 q88TJ2cN4LdXV92MdyaJUG7iM7oLFtu1YQWxiIvCnm07fqRP/zR/Dhl94A1nTqJdSVf9 3CCA== X-Gm-Message-State: APjAAAXnE1oIn7A13mXIyJfzj2AKUZAH1vETRfUDM0X73/c4lZYbjqt2 xeVUbRdExGVt+NnWP7zKnCBv+g== X-Google-Smtp-Source: APXvYqyBx1nTqGMRn9GsWSj0/giOcMCoKn/OjZ4stbz+xyyRba03IeYJrruyiFFcHRXe1jGKDNx4oA== X-Received: by 2002:a05:6e02:100b:: with SMTP id n11mr10655778ilj.212.1574351776819; Thu, 21 Nov 2019 07:56:16 -0800 (PST) Received: from [192.168.1.159] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id 133sm1342001ila.25.2019.11.21.07.56.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 21 Nov 2019 07:56:15 -0800 (PST) Subject: Re: [PATCH] block: add iostat counters for flush requests To: Konstantin Khlebnikov , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, Dmitry Monakhov References: <157433282607.7928.5202409984272248322.stgit@buzz> From: Jens Axboe Message-ID: Date: Thu, 21 Nov 2019 08:56:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <157433282607.7928.5202409984272248322.stgit@buzz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/21/19 3:40 AM, Konstantin Khlebnikov wrote: > Requests that triggers flushing volatile writeback cache to disk (barriers) > have significant effect to overall performance. > > Block layer has sophisticated engine for combining several flush requests > into one. But there is no statistics for actual flushes executed by disk. > Requests which trigger flushes usually are barriers - zero-size writes. > > This patch adds two iostat counters into /sys/class/block/$dev/stat and > /proc/diskstats - count of completed flush requests and their total time. This makes sense to me, and the "recent" discard addition already proved that we're fine extending with more fields. Unless folks object, I'd be happy to queue this up for 5.5. -- Jens Axboe