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=-10.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 A0FF2C433DB for ; Tue, 19 Jan 2021 19:43:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5EDBF22DD3 for ; Tue, 19 Jan 2021 19:43:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729887AbhASTmX (ORCPT ); Tue, 19 Jan 2021 14:42:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35532 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729731AbhASTmR (ORCPT ); Tue, 19 Jan 2021 14:42:17 -0500 Received: from mail-qk1-x731.google.com (mail-qk1-x731.google.com [IPv6:2607:f8b0:4864:20::731]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4C68C061573 for ; Tue, 19 Jan 2021 11:41:36 -0800 (PST) Received: by mail-qk1-x731.google.com with SMTP id w79so23061341qkb.5 for ; Tue, 19 Jan 2021 11:41:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.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=USI8gMqnOEP0NPOyscXOLLNBZa4yOXJQZOYn2OaTh1Q=; b=Xn/SYXuESn9TuzrTpkwqy0KF9mQlYPm/gABp230gAnCZj22Ouka/pWdRhg7kHKHWWf oz5hm+D0rUa7a6peP6K2LiFloZY81xxXidSuFlIRtCyCCVwuzUcqmtcCLbaGYP3Ib/pt 6jcO4sGAGN/Qv0j1FSmANuu4Yv/NVH0xKWnVr+u4nf8N2phM+K8xW/zqqByX3/DHEVPV 8cjyQMsYUlIfxR27wbAFOG48xOwwADlAAfeKk/dN1VWfj6X21IbaBCy6e0JMJpVNvwMn 1UGU551IACSOgv+Ua3R2Q7UyTFcigoTbocXDwQrIom0Jt0m9QGmU3LQLT67TjIDR0JpV Mfpw== 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=USI8gMqnOEP0NPOyscXOLLNBZa4yOXJQZOYn2OaTh1Q=; b=tRCoX4nGXBO8E9TslQvu2zc+Z+//sZdPHCYt+fe9qebQRDa5MLYLC4BysovvbXuxEc kqbSzNZJSr1ibYD8Nim7IW9xCzPlJgKK6FDxDJZ0v5/yYVwL8MbwjxP+gjQczr/T6mZo 0+t2Mdppox6+PpYo94MhQm77j+DTnKfdOQhyr2b/OhVinKy5WDU1gO1WhlSEusQlj8Gn zwHoch5FEJg6lVv/FvK5Hncco6gFZCjE6sAsULurobafnh6GUfk72pi8P1Kn+jX+O5Vw PE0dCWgTI4i1vB2KABlZEzJwGjq8iHdhGTTVxXBI7jthEBgbCA+oA/SQsjPkcSBcv4E8 OiQQ== X-Gm-Message-State: AOAM530KXR6pLl+KRt6HziRdn1i0d2kRyklhhSS9IvtwAQTvzW+1F13S jKFSMdfyMgHu3TCQc43ha0TVdhZ6tXZtlJNdvbk= X-Google-Smtp-Source: ABdhPJwgT474ZlHCiLLeRzU9doYA7RxaXdu98dhPwluQjnv88ZTOTVvdaD7GEXWPMvb3CIlUtlcy1Q== X-Received: by 2002:a05:620a:80c:: with SMTP id s12mr5864833qks.248.1611085296139; Tue, 19 Jan 2021 11:41:36 -0800 (PST) Received: from ?IPv6:2620:10d:c0a8:11d1::1325? ([2620:10d:c091:480::1:a066]) by smtp.gmail.com with ESMTPSA id u65sm13737141qkb.58.2021.01.19.11.41.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Jan 2021 11:41:35 -0800 (PST) Subject: Re: [PATCH RFC 4/4] btrfs: introduce new read_policy round-robin To: Anand Jain , linux-btrfs@vger.kernel.org Cc: dsterba@suse.com References: <8e0afaa33f33d1a5efbf37fa4465954056ce3f59.1610324448.git.anand.jain@oracle.com> From: Josef Bacik Message-ID: Date: Tue, 19 Jan 2021 14:41:34 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <8e0afaa33f33d1a5efbf37fa4465954056ce3f59.1610324448.git.anand.jain@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 1/11/21 4:41 AM, Anand Jain wrote: > Add round-robin read policy to route the read IO to the next device in the > round-robin order. The chunk allocation and thus the stripe-index follows > the order of free space available on devices. So to make the round-robin > effective it shall follow the devid order instead of the stripe-index > order. > > Signed-off-by: Anand Jain > -- > RFC because: Provides terrible performance with the fio tests. > I am not yet sure if there is any io workload or a block layer > tuning that shall make this policy better. As of now just an > experimental patch. > Just drop this one, if we can't find a reason to use it then don't bother adding the code. The other options have real world valuable uses, so stick with those. Thanks, Josef