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 04D72C31E4B for ; Fri, 14 Jun 2019 13:45:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D1C5E2168B for ; Fri, 14 Jun 2019 13:45:10 +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="CmA0VwwE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728274AbfFNNpF (ORCPT ); Fri, 14 Jun 2019 09:45:05 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:46764 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728267AbfFNNpF (ORCPT ); Fri, 14 Jun 2019 09:45:05 -0400 Received: by mail-qt1-f194.google.com with SMTP id h21so2426012qtn.13 for ; Fri, 14 Jun 2019 06:45:05 -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=OoE9TTwZ2oX4l67lO4UKKcsLXQImUKGP20eXDpNCJrQ=; b=CmA0VwwEqJigtFceHJxQeYm3whQH2/+4pEJ/T/TOOR81IIrusYRBFbvLnkk2d8y9zK n1zgsO3A3KhD6bJjzcoi53PSKIjlVu7yoeqsxOpjp0j0dLgQPuSs84L29BAT52XfCqPT 0l9Luwh6m1xaqa5JgO0hohC6Kgb3fA6L1z+xJnvYDCe1p1/uQVjEmDenWKlttKNMi694 O2zTv0sNHEM8H6IXKqNLita+OS5cAnoiCLwBMN8+xxSjPZvbkjNWrxPhgBUR84mn84bD iTnsipFfh1WbMAjWOuKPoxmuL5PsSVfcthoirTwInDvf05QM2YmJfPADbHinscIK24+J HwiA== 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=OoE9TTwZ2oX4l67lO4UKKcsLXQImUKGP20eXDpNCJrQ=; b=uHNF4EUQhI0+Ml8LXh60p3E8I2mnV2EqtPzfieKNC1EqrvaMflD755zWtvmHdooaa+ AmAzJEzyPQoUVDW3znu33DSMqmy5JgifLEaSFwps0ZPjy562JdvKdfvU3jCO2xOM146O rFxpbIweCmZkTAVGwpL3jwH+RAg3Dk49r0oH62vqoEwf4Y2dbRRWATlWaZrbg5WhoILH 5foJmgDYDojTfwziGApztlRCBDyshh6MiqpjAOkqhVWieJTNqIYE5SAwy1JiXVnYVBLK DCqPamXhJFHI4ETwkRvddTwwT/E2yABrRWNyDGYE9Gtcv9gONZkfaowujy2MGyAh7bTk chGQ== X-Gm-Message-State: APjAAAWGS3I7e3iWNLnhyHyMfCK6dVHNk7NosTdpHQRfiGMWd1LCV0lO S4CcaQCvUqU/07ICT+fVu/K5/g== X-Google-Smtp-Source: APXvYqzK0goCeSYPjF5bhIPBakUW9p6CVwC+vyGH1n/OjNW5KJjnzAEtFGiENd0PQTCzCI2Gq26ImQ== X-Received: by 2002:ac8:374b:: with SMTP id p11mr77934298qtb.316.1560519904543; Fri, 14 Jun 2019 06:45:04 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::a658]) by smtp.gmail.com with ESMTPSA id c30sm1843863qta.25.2019.06.14.06.45.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 14 Jun 2019 06:45:03 -0700 (PDT) Date: Fri, 14 Jun 2019 09:45:02 -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 4/8] Btrfs: stop using btrfs_schedule_bio() Message-ID: <20190614134501.cjnrsb5n6jtteqex@MacBook-Pro-91.local> References: <20190614003350.1178444-1-tj@kernel.org> <20190614003350.1178444-5-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190614003350.1178444-5-tj@kernel.org> User-Agent: NeoMutt/20180716 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jun 13, 2019 at 05:33:46PM -0700, Tejun Heo wrote: > From: Chris Mason > > btrfs_schedule_bio() hands IO off to a helper thread to do the actual > submit_bio() call. This has been used to make sure async crc and > compression helpers don't get stuck on IO submission. To maintain good > performance, over time the IO submission threads duplicated some IO > scheduler characteristics such as high and low priority IOs and they > also made some ugly assumptions about request allocation batch sizes. > > All of this cost at least one extra context switch during IO submission, > and doesn't fit well with the modern blkmq IO stack. So, this commit stops > using btrfs_schedule_bio(). We may need to adjust the number of async > helper threads for crcs and compression, but long term it's a better > path. > > Signed-off-by: Chris Mason Reviewed-by: Josef Bacik Thanks, Josef