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=-5.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 723F8C31E4D for ; Fri, 14 Jun 2019 13:43:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4AB6B2168B for ; Fri, 14 Jun 2019 13:43:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=toxicpanda-com.20150623.gappssmtp.com header.i=@toxicpanda-com.20150623.gappssmtp.com header.b="QR/Frpj4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728249AbfFNNnq (ORCPT ); Fri, 14 Jun 2019 09:43:46 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:33075 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727898AbfFNNnq (ORCPT ); Fri, 14 Jun 2019 09:43:46 -0400 Received: by mail-qt1-f195.google.com with SMTP id x2so2510548qtr.0 for ; Fri, 14 Jun 2019 06:43:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=toxicpanda-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=aXm35D07rUjPalP4CfdXm4RG5Oa6TLe+BWj9APerSEg=; b=QR/Frpj4TG8mlIKMQ8x4IzLOAFOk25NuIc41EaC9lVa+w/n88BtrrXCtofyiOLcBhQ Ezeq0yN2wzhUdN1vU2w1zT+V527yXqLZF/+MLPfVmTNAtX7P4rRVe0DL2RGw1IGwvkhj 0KDirUSeO28izbosQHeBo0cYVQuorCRyA8FkTx4KP3ZVVmk2W76yy5ocUMvKbrVs7f5E G+deGxfel0FA+FY110QfZw7k7b3xnpeyMTNzP4c19Tm8CffN2A/jkYI/34ElKabeYW5I b0HU2seMrkx9Fzxz2rqbfqxlowdUUvCJuIQL/eGCkPMU4cK5IaFV7RZmAMvH+obj+Kr1 xdzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=aXm35D07rUjPalP4CfdXm4RG5Oa6TLe+BWj9APerSEg=; b=sz964ER2tu9qO1TxyigoQKQHvGdVIdpXRz/UKVmgWPqA7gAdi4m1hGArZaEAvdaZ/B ae4se/V/Xk6336wIH+SjM1SbqqBi69ZKfUcGg6GOoJcu1ldzSntGC38KgONrXQlVkpFR /ENiOgFMUbhxUwI3O+8vFXRFOqXG2FhT9f3+zvkyISirjOKBStZEVtpiM+wsR8aGtyUn b6cOzFzOY7hBt4axEgWTwVn+ogQQ0lbmD4t3xal2WVACpvEOSBzvUf8cKMH6FVUnNDI1 MfPWBppmVAkCiyqSaDJ86CHUEmWu8ZrtKRmdX8bDDV2Am54ME/nsUKqJwVKmXWKah8Xk 02Cg== X-Gm-Message-State: APjAAAXJMeGYPg6wTYSEyY9w3sFajWb02nyI5CLd23wNB9Nv8miFkhEN tyx74neTgkkKqq/Sl3vE0+4nWQ== X-Google-Smtp-Source: APXvYqwz2/lYE4zseDXYhlp0RL/XY7Q0dZxV33vLDM4hSXrLx92LsZ3CWxcDYpnpK2WqRaqGxcv0MA== X-Received: by 2002:a0c:ba97:: with SMTP id x23mr8397472qvf.133.1560519825110; Fri, 14 Jun 2019 06:43:45 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::a658]) by smtp.gmail.com with ESMTPSA id s64sm1507782qkb.56.2019.06.14.06.43.44 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Jun 2019 06:43:44 -0700 (PDT) Date: Fri, 14 Jun 2019 09:43:43 -0400 From: Josef Bacik To: Tejun Heo Cc: dsterba@suse.com, clm@fb.com, josef@toxicpanda.com, axboe@kernel.dk, jack@suse.cz, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 3/8] blkcg: implement REQ_CGROUP_PUNT Message-ID: <20190614134342.rtm4iwxgzbsueyfg@MacBook-Pro-91.local> References: <20190614003350.1178444-1-tj@kernel.org> <20190614003350.1178444-4-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190614003350.1178444-4-tj@kernel.org> User-Agent: NeoMutt/20180716 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Jun 13, 2019 at 05:33:45PM -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 > Cc: Chris Mason Reviewed-by: Josef Bacik Thanks, Josef