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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 7D838C31E50 for ; Sat, 15 Jun 2019 18:29:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 532312184D for ; Sat, 15 Jun 2019 18:29:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560623378; bh=drg1GKt+ib6Bp6LZP0o/5c5PxF6plAd2lkDNtWcgiCQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ryhCxupeIRwUp+bxFlcnYbyMnl6UaQ3Fb6iPQnA0Vw0PHKO9r1Uif7HIRyfzG0WqV b+6qPLc6UrM5lAUQw7V4MajT0oAOeVnOshqCSh/MGuvsGGeGpQPPNv/+uDOINh1Zud /5FAPZuSoKh5ThdoC7q3eJGnFDimBsJXUJSBGkow= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726366AbfFOS3h (ORCPT ); Sat, 15 Jun 2019 14:29:37 -0400 Received: from mail-qk1-f193.google.com ([209.85.222.193]:45666 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725535AbfFOS3h (ORCPT ); Sat, 15 Jun 2019 14:29:37 -0400 Received: by mail-qk1-f193.google.com with SMTP id s22so3795741qkj.12; Sat, 15 Jun 2019 11:29:37 -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:in-reply-to:user-agent; bh=lZWCDkdCZYN5S0+Ul2IxfiRO29wLQTcP6wWsFwWlu8s=; b=PphbEiU9i51xnvtm9V73bQYuo5cIfkeTXUcMOZ155zwXkW9k1v0AszL3HGTB5AYeTT fMmrhBXuFr0sPCV8eoVVlAksctrq0Tp9EfiShBGan9umj+gy1onSVWWyp/YbfNQ8hPO0 /YFxWG/bnNyKmMK9S+h8oW63Tm9QU2mlTRob+1FyRqmyB1V5pEABc7CIakDbt8CPe9zk 5OthH7bBlGrWW0NoCY261eL7JxLB03tRJCoGI4wGle7j93IpmuJsT+faKyIQzcXuW9CI btceBey/cK2gygHTP53JgjcqvJ2KM9kFr8n+9XEQeuWH9QBQVX9jjMSGKTp/Ed+ovdcz DqIA== 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:in-reply-to:user-agent; bh=lZWCDkdCZYN5S0+Ul2IxfiRO29wLQTcP6wWsFwWlu8s=; b=YrJsVPB46VnybZ6pvHnHjY6HMrSeX/gus1txUHXOwRyDr2FIamXMCsiuWRn3tu9mOV hbYjika5yo1yBq4+4L53t5P7VlXGjBxdsHn/G3lAxaVpjcGswnWAvN9Ms5M9Kj+H1wSB Z12X0UlNsBt/TCmmm54ish8unSVy7rHsUpv6DKos26iU+jBN+Av82FcyADN5Zu8QvGR9 3maBS/rENyGssPvbRg8GnQqz1+rwQAluN/V5baMxClAjeJts37hsxNl7r3oTH6iRpg/p iYm0Qx342UpkqUgJw+fUPoKP3tgdhDQ2jb4dg9zf6eLXtZLpOnb+UBg8R9EwlqUVObHx k+8A== X-Gm-Message-State: APjAAAXW54WSp2Z5E1QfMNc3UuA3Y2N29aPwwXYL8WbTvzGuA8C5ub8L eCo6VsjWRJZwHl1zKCXqYyE= X-Google-Smtp-Source: APXvYqx5M5Vccns8o0Sb2Ujl3A2MXEaAf0YNJo2yyhXxfxv1/7ALY9MC70OvLseEU3n6ihO/8XZSew== X-Received: by 2002:a05:620a:124c:: with SMTP id a12mr82297214qkl.336.1560623376408; Sat, 15 Jun 2019 11:29:36 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::4883]) by smtp.gmail.com with ESMTPSA id c5sm4004284qkb.41.2019.06.15.11.29.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 15 Jun 2019 11:29:35 -0700 (PDT) Date: Sat, 15 Jun 2019 11:29:33 -0700 From: Tejun Heo To: dsterba@suse.com, clm@fb.com, josef@toxicpanda.com, axboe@kernel.dk, jack@suse.cz Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 4/9] blkcg: implement REQ_CGROUP_PUNT Message-ID: <20190615182933.GH657710@devbig004.ftw2.facebook.com> References: <20190615182453.843275-1-tj@kernel.org> <20190615182453.843275-5-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190615182453.843275-5-tj@kernel.org> 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, On Sat, Jun 15, 2019 at 11:24:48AM -0700, Tejun Heo wrote: > When a shared kthread needs to issue a bio for a cgroup, doing so > synchronously can lead to priority inversions as the kthread can be > trapped waiting for that cgroup. This patch implements > REQ_CGROUP_PUNT flag which makes submit_bio() punt the actual issuing > to a dedicated per-blkcg work item to avoid such priority inversions. > > This will be used to fix priority inversions in btrfs compression and > should be generally useful as we grow filesystem support for > comprehensive IO control. > > Signed-off-by: Tejun Heo > Reviewed-by: Josef Bacik > Cc: Chris Mason The blkcg patches, especially this one, need Jens's review. Jens, if you're okay with the changes, please let me know how you want them to be routed. Thanks. -- tejun