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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_MUTT 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 BDA8DC31E52 for ; Sat, 15 Jun 2019 15:57:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9722C21841 for ; Sat, 15 Jun 2019 15:57:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560614271; bh=pt3SyxYCml22bVU9o7vVEjo/cpZQ112WzpGaw/J1g+8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Bz79QhCKAnZWiOxizpQQN6D94TuO87+5T6GQP+vGi+PA5Vt4NdOgNmdXfbqRedOl3 FnHYplZyXRWagWgGqaBEeCcTkoTXtMngPi2g85lifLuuNzFYzj+folLhpLvZz5GLvm G/soyorvHbVmZejXFFnU9SI5T7t1AaBaAe8Or4j0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726859AbfFOP5s (ORCPT ); Sat, 15 Jun 2019 11:57:48 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:33029 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726405AbfFOP5r (ORCPT ); Sat, 15 Jun 2019 11:57:47 -0400 Received: by mail-qk1-f195.google.com with SMTP id r6so3704108qkc.0; Sat, 15 Jun 2019 08:57:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to :user-agent; bh=V1Xn65jFA9fLzGnZCICEwL6tUShlHAvAc5j9I2/vRW4=; b=csyg6vgm0i4uNhPsUxiT5I9v9LOyUNu0/a9saVtXHrnPe9wqOlbnYU16Udzo53uh/u ntH7pwRtBjuYbe9ZRhTBP3W/jUlEuQnIvB0w7IG3x9Ic2hAnHAbtU0CPHO2gkqHUsvN6 cbfvLAcvtmBIdwilZEn2cBDPcUNiKMGQEWZcQt6R+ZKmEM4/Opb3ub+9xk/GktAgEGmR 7jDLFDvE5TNOV/yA2grBclF2D5ZeFv5ddWM5MPXh6kBco8WTEXIVO1CcoKFaaCofb2Bt XsIzD6JAPKS4+AxN7vQovTd0s8Zxat1tSWhNEOzrhnY6XwBMzmfPPOwBkM1nY3UjStQW Xtbw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition :content-transfer-encoding:in-reply-to:user-agent; bh=V1Xn65jFA9fLzGnZCICEwL6tUShlHAvAc5j9I2/vRW4=; b=coLPfFv7f+hAIkS0BM92BaoAp8P/hkPfbPRWJxIKN1boopRzD/uOcp03eoAVY7LbyM 2GmfPuLf1G+WTZPlzGIJy862384xRHhYrnPfJ7veYR3wP/u9g9P1UOFsk5fgQkGpF/P2 uuPCDa6Rl8WPd1yUB6PhuywUNJ5ReXbAuaeRryFt7nNgzKYW5dnpdN3MD5w5yIhxdjKF XrY6o2X5ndjiPxdUuBEPwJr7b6R1Vc1PGDIOPjgunG9NFwx9VU0sAdOMM1lNg/fF4Rrj 1jU2SY6qEg0O3FyHAmuxlFEQjW+fY53Wz8wdd31UyVwBcrRXwuCH48XHqObT66MPNLxV 0N9A== X-Gm-Message-State: APjAAAWz5eXPQERHfp1ZAG/YL56uRSqQiq7m3Q/MAD+hAx+0Gi5SzHEB KryA2GCForr8pyM2/Gq9D00= X-Google-Smtp-Source: APXvYqw7pW50FWwPRrhOjvP+Dt3tlqNNZWVvipaSTxtXb/kfSgJbt5OwlMOikhxcouvwT5smDdGKnA== X-Received: by 2002:ae9:f702:: with SMTP id s2mr82033743qkg.28.1560614266380; Sat, 15 Jun 2019 08:57:46 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::673a]) by smtp.gmail.com with ESMTPSA id g10sm3067097qkk.91.2019.06.15.08.57.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 15 Jun 2019 08:57:45 -0700 (PDT) Date: Sat, 15 Jun 2019 08:57:43 -0700 From: Tejun Heo To: Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= Cc: axboe@kernel.dk, newella@fb.com, clm@fb.com, josef@toxicpanda.com, dennisz@fb.com, lizefan@huawei.com, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, kernel-team@fb.com, cgroups@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, bpf@vger.kernel.org, Josef Bacik Subject: Re: [PATCH 08/10] blkcg: implement blk-ioweight Message-ID: <20190615155743.GF657710@devbig004.ftw2.facebook.com> References: <20190614015620.1587672-1-tj@kernel.org> <20190614015620.1587672-9-tj@kernel.org> <87pnngbbti.fsf@toke.dk> <20190614150924.GB538958@devbig004.ftw2.facebook.com> <87blyzc2n9.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87blyzc2n9.fsf@toke.dk> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Archived-At: List-Archive: List-Post: Hello, On Fri, Jun 14, 2019 at 10:50:34PM +0200, Toke Høiland-Jørgensen wrote: > > Within a single cgroup, the IOs are FIFO. When an IO has enough vtime > > credit, it just passes through. When it doesn't, it always waits > > behind any other IOs which are already waiting. > > OK. Is there any fundamental reason why requests from individual > processes could not be interleaved? Or does it just not give the same > benefits in an IO request context as it does for network packets? I don't think there's any fundamental reason we can't. Currently, it just isn't doing anything it doesn't have to do while preserving the existing ordering. One different from networking could be that there's more sharing - buffered writes are attributed to the whole domain (either system or cgroup) rather than individual tasks, so the ownership of IOs gets a bit mushy beyond resource domain level. Thanks. -- tejun