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=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 034F7C31E4B for ; Fri, 14 Jun 2019 15:09:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB63721537 for ; Fri, 14 Jun 2019 15:09:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560524971; bh=YlnbKY76MU++cPKthpCvz9e6XM7nVGVURhmpeatu9B4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=d7xRvwLO14qrk3pRGVrzNrwJ/rhBEr5IPcu/MIJmMwYA5/Itm9j9UFEb8/q0wUKQc cCYaTX4VxxLLgtBMMdJjFQ9PyOEXzNsej5nczur7hXRESobUiHiL8K1w4BpDGhA995 fBVvQOjqZnaw3IGdr9QnmEqaWbX8B0P1m8SopPhU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725868AbfFNPJb (ORCPT ); Fri, 14 Jun 2019 11:09:31 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:46993 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725837AbfFNPJb (ORCPT ); Fri, 14 Jun 2019 11:09:31 -0400 Received: by mail-pl1-f195.google.com with SMTP id e5so1128901pls.13; Fri, 14 Jun 2019 08:09:30 -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=+I9U1GODgSkyxPAIv5uSBlih1n/pRySECC43JZGkdsQ=; b=iGhc4xzitJMk67sXbQMyBo8eYE8TxhKJEDf+KuuPxlnOLUZFysidCzwr54Kzzy0K2J D+GJRX71MpXYgXx2M6apuBILbtB+nlVv2HxnXhyaQJh8VlGfzYaUAn2jZSunbRUcJP+x iOB3D7jvu5eEN6YbwgH60SuKTejWz4B6PizS20cko5zfs7ZiBvyTkCfK/CSqY5Bns3l8 Ro6EsJZk30weiEJY/Uk5TEteCCGXB8XYvuQXqPh/3FoevGvIok7Er3BS5HLnUo9gdnw3 FP2pyydyRWD6S3lNwlB6S79WFXpwubyELDGZOmGBXGY7MLSjmvWneimvwEkDnHpcmFWV 0G/g== 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=+I9U1GODgSkyxPAIv5uSBlih1n/pRySECC43JZGkdsQ=; b=HyJqtfDS72O5+9b4rUTlWezjRoRGjZcozrgUUZAu/pHK3Ra2m5TzIiRFzDuS26+PtL BrTEV7VCmGA6vZkz0pXKdvVNAv25hJ+TR3tbOs4mLP/wmzmrVQEjBenljYN9TsRRumrC e51XXRACUySdMtCGx+CMvJ3baFsoIv2nGjl3RrKEsxNYfWBrkDkNURBPUJ6YgqHRISny lGSZGSV3l2vNFsKq5bYdRSeykmffCti5Cl1MT5soFduDfrcDLD3bdkXEBwi2GSdZjBha oxF0bnd2MGzqz1jGCdKtf0fJ3r18iudr7oV9NdarQp9dM0Ld0IWQuSJWMS7CYOf3HwVC EdNg== X-Gm-Message-State: APjAAAXJQhL/2ux5JThI5KGU1SoHqOQv9PkNNXpkEs48awzC58nuDUEH 8F2s0wQiWoe0Q73tZmHsO0Y= X-Google-Smtp-Source: APXvYqxzOCKBrFEtUYYWecwehqGBRjbcRqqz2d1PNNKgZEyBo102COqcOPB0Jz3DOPgdv6CXMm9Xlg== X-Received: by 2002:a17:902:b70f:: with SMTP id d15mr12366371pls.318.1560524969921; Fri, 14 Jun 2019 08:09:29 -0700 (PDT) Received: from localhost ([2620:10d:c090:180::1:b330]) by smtp.gmail.com with ESMTPSA id a22sm4039041pfn.173.2019.06.14.08.09.28 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Jun 2019 08:09:28 -0700 (PDT) Date: Fri, 14 Jun 2019 08:09:24 -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: <20190614150924.GB538958@devbig004.ftw2.facebook.com> References: <20190614015620.1587672-1-tj@kernel.org> <20190614015620.1587672-9-tj@kernel.org> <87pnngbbti.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: <87pnngbbti.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 Hello, Toke. On Fri, Jun 14, 2019 at 02:17:45PM +0200, Toke Høiland-Jørgensen wrote: > One question: How are equal-weight cgroups scheduled relative to each > other? Or requests from different processes within a single cgroup for > that matter? FIFO? Round-robin? Something else? Once each cgroup got their hierarchical weight and current vtime for the period, they don't talk to each other. Each is expected to do the right thing on their own. When the period ends, the timer looks at how the device is performing, how much each used and so on and then make necessary adjustments. So, there's no direct cross-cgroup synchronization. Each is throttled to their target level independently. 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. Thanks. -- tejun