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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 F2427C55ABD for ; Fri, 13 Nov 2020 21:36:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7D6920A8B for ; Fri, 13 Nov 2020 21:36:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726749AbgKMVgU (ORCPT ); Fri, 13 Nov 2020 16:36:20 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:42935 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725981AbgKMVgU (ORCPT ); Fri, 13 Nov 2020 16:36:20 -0500 Received: by mail-pg1-f196.google.com with SMTP id i13so8141108pgm.9; Fri, 13 Nov 2020 13:36:20 -0800 (PST) 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=Jm0UQg+mdszuwGSP+rSGtDVxYjXFAKTIf/hP3qOCt5s=; b=n1oMl71ey4nw84qSa7Ff98YjFNCQwsWUwhOZTLM63m8M73DuV2EvqBjkrydDnmyMVD h2CsDIdBsAlkIB7yjPsmzqUfkOcjJWtJWn4F6gsOGgmToST+LBkEjtl0lElUKmbB36qh Zatwxwpy1S9GDG/6Xssvg/5kUNvrC6JiMXT0fH0r6Wv9HMOyz+ESMrAWGJAG+5IB/5lS Bs8BJJlFldHyy9TxpOhsBM2oPLuyqp5bvnWbpeSATvvJhs6aF7CrcH7As4DQpEYy5hkq 7lfC/+VytOqglMxFgeHIJpgQR0cFtCbgY1xu4PzNm1bLPvQfiQgDE4DR8AD+tnK2uxKV s0yQ== X-Gm-Message-State: AOAM531l2XrxsMnnP/Vo1nfw3tAzYdrSaBdQ9h/EUo/5Mtl2OCoqzG0F pMfpN1f+b0vwpxNae5aUA64= X-Google-Smtp-Source: ABdhPJyd2mq3CcH87fe4TuuOQePNIWrpkvt9hnJ7sQTx3mTF7rd18fMqO1nNSZ6lKYfYZ9gwY9KR7A== X-Received: by 2002:a62:8cd6:0:b029:18b:ad92:503b with SMTP id m205-20020a628cd60000b029018bad92503bmr3670399pfd.77.1605303379651; Fri, 13 Nov 2020 13:36:19 -0800 (PST) Received: from ?IPv6:2601:647:4802:9070:be97:ffd:339d:919c? ([2601:647:4802:9070:be97:ffd:339d:919c]) by smtp.gmail.com with ESMTPSA id a84sm10727208pfa.53.2020.11.13.13.36.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Nov 2020 13:36:18 -0800 (PST) Subject: Re: [PATCH] iosched: Add i10 I/O Scheduler To: Jens Axboe , Rachit Agarwal , Christoph Hellwig Cc: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, Keith Busch , Ming Lei , Jaehyun Hwang , Qizhe Cai , Midhul Vuppalapati , Rachit Agarwal , Sagi Grimberg , Rachit Agarwal References: <20201112140752.1554-1-rach4x0r@gmail.com> <5a954c4e-aa84-834d-7d04-0ce3545d45c9@kernel.dk> <10993ce4-7048-a369-ea44-adf445acfca7@grimberg.me> From: Sagi Grimberg Message-ID: Date: Fri, 13 Nov 2020 13:36:16 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: 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-kernel@vger.kernel.org >> But if you think this has a better home, I'm assuming that the guys >> will be open to that. > > Also see the reply from Ming. It's a balancing act - don't want to add > extra overhead to the core, but also don't want to carry an extra > scheduler if the main change is really just variable dispatch batching. > And since we already have a notion of that, seems worthwhile to explore > that venue. I agree, The main difference is that this balancing is not driven from device resource pressure, but rather from an assumption of device specific optimization (and also with a specific optimization target), hence a scheduler a user would need to opt-in seemed like a good compromise. But maybe Ming has some good ideas on a different way to add it..