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=-2.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_NEOMUTT autolearn=unavailable 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 7AEB6C31E45 for ; Thu, 13 Jun 2019 15:05:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5063F21744 for ; Thu, 13 Jun 2019 15:05:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toxicpanda-com.20150623.gappssmtp.com header.i=@toxicpanda-com.20150623.gappssmtp.com header.b="oP6ERCa1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732971AbfFMPEz (ORCPT ); Thu, 13 Jun 2019 11:04:55 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:40369 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732463AbfFMORK (ORCPT ); Thu, 13 Jun 2019 10:17:10 -0400 Received: by mail-qt1-f195.google.com with SMTP id a15so22707904qtn.7 for ; Thu, 13 Jun 2019 07:17:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=IdWKzce3sZz9+VK0mMGhceU7W1z4LrhQkC1c9OeYugc=; b=oP6ERCa1F6T8r6pSHlZINu6LknBTF+UPLpwmpRJcH+T6FdeYawjrBm7oQ0iaSVxmjD LZmwbZomBs1w1G2Z2uECjOVu4ctdMmjAbGswoZajXSueNHfNEi2kDdbB0eo5K/L6TPX7 gZDgT2bbG1XJxfKdQTmNc/rRjKzTRncWVcJVin9R+eQOLHXhMw81x04KLiHKKskUszQf ZBhBJw5X9u7/w7EZhQAiKlEqEZsI6T8SkRldzr2n/0VkSPQGDovwNcD8pbdF8P8kD9fH yrx5FvRP/YCxnPdJUo/PdMnD9HHxHisaI1pK2EJyShl5GyzSbTt0LN5tNALrEQUHkLxB Gsyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=IdWKzce3sZz9+VK0mMGhceU7W1z4LrhQkC1c9OeYugc=; b=PT2v7DMUbSJCVLbjNG9vOcXdBhKvZfj4pvSd3u5loKP2HahQf/DM0Tf5lSrq5smoUM aIK2NZYvgWiv3S2GRD9PZOyy9eYzCqO67owpS7XI8EOiOBFbRGB42YzFcqBCMyDQ8w+e ioP1XS1Z9Qo9c1SpwpLUpB6dK83kEZ+WndeA2ThIodhoDmrTpuSR40OeFey+4XxcvJH/ IkihV2N+yJOZrc4TeSlpSIfJxiHQlYjVOHfq3MKypm85IpwYuJAmtelh06ctjfUGFXMk pg/1yN0t+gsc+0gcIA2MxoIzwrO+k5HtlXyMIHv1tGgNqTcSMYuzkZODzhzh7RfhTUAd SKdQ== X-Gm-Message-State: APjAAAUIuNarv7W1YunoaDWiFYFfjmkazbYL4GULAQbC2ciPJG+9BtYd 06/L2qD1laIa0twRohsq70FTZw== X-Google-Smtp-Source: APXvYqx5jPsVPa9dGQd9Bui4/XGgLT6BOzvijxJlMoqU0XvFjHiv3oPKH2im4jOl3Wj+44uE9UzG2A== X-Received: by 2002:ac8:25dd:: with SMTP id f29mr66160028qtf.144.1560435429256; Thu, 13 Jun 2019 07:17:09 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::9d6b]) by smtp.gmail.com with ESMTPSA id 102sm1338356qte.52.2019.06.13.07.17.08 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Jun 2019 07:17:09 -0700 (PDT) Date: Thu, 13 Jun 2019 10:17:07 -0400 From: Josef Bacik To: Naohiro Aota Cc: linux-btrfs@vger.kernel.org, David Sterba , Chris Mason , Josef Bacik , Qu Wenruo , Nikolay Borisov , linux-kernel@vger.kernel.org, Hannes Reinecke , linux-fsdevel@vger.kernel.org, Damien Le Moal , Matias =?utf-8?B?QmrDuHJsaW5n?= , Johannes Thumshirn , Bart Van Assche Subject: Re: [PATCH 13/19] btrfs: avoid sync IO prioritization on checksum in HMZONED mode Message-ID: <20190613141706.tbxc5wufplfybfib@MacBook-Pro-91.local> References: <20190607131025.31996-1-naohiro.aota@wdc.com> <20190607131025.31996-14-naohiro.aota@wdc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190607131025.31996-14-naohiro.aota@wdc.com> User-Agent: NeoMutt/20180716 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Fri, Jun 07, 2019 at 10:10:19PM +0900, Naohiro Aota wrote: > Btrfs prioritize sync I/Os to be handled by async checksum worker earlier. > As a result, checksumming sync I/Os to larger logical extent address can > finish faster than checksumming non-sync I/Os to smaller logical extent > address. > > Since we have upper limit of number of checksum worker, it is possible that > sync I/Os to wait forever for non-starting checksum of I/Os for smaller > address. > > This situation can be reproduced by e.g. fstests btrfs/073. > > To avoid such disordering, disable sync IO prioritization for now. Note > that sync I/Os anyway must wait for I/Os to smaller address to finish. So, > actually prioritization have no benefit in HMZONED mode. > This stuff is going away once we finish the io.weight work anyway, I wouldn't worry about this. Thanks, Josef