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=-11.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A31E6C2D0A3 for ; Wed, 4 Nov 2020 17:22:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44A6720781 for ; Wed, 4 Nov 2020 17:22:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="vLNqzKFm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731496AbgKDRWr (ORCPT ); Wed, 4 Nov 2020 12:22:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726604AbgKDRWr (ORCPT ); Wed, 4 Nov 2020 12:22:47 -0500 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF89AC0613D3 for ; Wed, 4 Nov 2020 09:22:46 -0800 (PST) Received: by mail-wm1-x341.google.com with SMTP id c9so3125090wml.5 for ; Wed, 04 Nov 2020 09:22:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:references:from:autocrypt:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=BkNkEbxQfAYhRKuxcublC9y3+vugxwjCkxs4Zpl2lbQ=; b=vLNqzKFmM8Cngq9ywvdPgokn+ivAA8DYx6HqLELDXOsIgGlymeeZofCLp5C1qQUA/z Nzc8LHDNeAOF31wAhno5QiH1DwRpcaQNVS1wab37OMNnDI+nzqKueR6wRxE89t0Lyh/+ Mr18dZJcvo4TeQRfQtNRTX98HhX+gbK6vscvw6MbqXbFPGCzwpgRy1V76gWpMq0iRT5o YFga013y73zFaGXSN7JqvhYTiWt3bdS7IyakMiTwnY+OWEqk7tXm3PTt2CpgthhRwyWn G0Vx15BEo2V8KHZ3TTzCCidsftmhoohqfqTH3bOhkOCC2gtYYwMI0eJxdJZ6nzensvHi Mdqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:autocrypt:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=BkNkEbxQfAYhRKuxcublC9y3+vugxwjCkxs4Zpl2lbQ=; b=XrRyZHiI1/HAqv8wpUgKJ/gZQmkbM6q1ZP5o4/nngjMU3anR1U5su+Hwu6YyueI/qA sNacN3pd+PFVgtam9Xp094W9N85H0SbSOnJoa0GV0CrAJY+pVv8HHiuYxQCCTGBpxnX4 qVXKKuyBheZAKPqiN48qMVB6lWOLnv0TLOM75FR3O/syyqjdyy0pyUzNRtCN5cktpH4y t/7xIWgzbKnLhvwmcgZb4sX+Vms1m+ciQNpKDm3WfG3dhW5MkkfaAhAzzpSoZT1kBZTC 2uCJco9tTzLCPpa5hzpw4Ze0pcX7NFxECYzUUl4x+yw0P571hcYpG5bErcVKzIsvWNY5 Np3A== X-Gm-Message-State: AOAM532jqGclClgjGYoMzim2oRk4vtbklz+fD/vOl+aKCkzSQMNqP/pz XTC1SPisoFqL/GlBHnekc95JYLP3lPG2Jg== X-Google-Smtp-Source: ABdhPJy9GGV3NdPWKOkSl3dOy33DCrK61gXPsRvYe/O+SiJJYt0T01IB/sxyxN9W6vmii/9QxhSyxQ== X-Received: by 2002:a1c:5605:: with SMTP id k5mr5368929wmb.99.1604510565253; Wed, 04 Nov 2020 09:22:45 -0800 (PST) Received: from [192.168.1.121] (host109-152-100-164.range109-152.btcentralplus.com. [109.152.100.164]) by smtp.gmail.com with ESMTPSA id t199sm3072785wmt.46.2020.11.04.09.22.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 04 Nov 2020 09:22:44 -0800 (PST) To: Amy Parker Cc: Chris Mason , Josef Bacik , David Sterba , Btrfs BTRFS References: <2a3d84dfc9384eed8659963d1dafedabb3f17c75.1604444952.git.asml.silence@gmail.com> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [PATCH 1/4] btrfs: discard: speed up discard up to iops_limit Message-ID: <2be31971-da4f-1a39-cb01-0c13b35cf2aa@gmail.com> Date: Wed, 4 Nov 2020 17:19:44 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 04/11/2020 15:29, Amy Parker wrote: > On Wed, Nov 4, 2020 at 1:50 AM Pavel Begunkov wrote: >> >> Instead of using iops_limit only for cutting off extremes, calculate the >> discard delay directly from it, so it closely follows iops_limit and >> doesn't under-discarding even though quotas are not saturated. > > This sounds like it potentially be a great performance boost, do you > have any performance metrics regarding this patch? Boosting the discard rate and so reaping stalling blocks may be nice, but unless it holds too much memory creating lack of space it shouldn't affect throughput. Though, it's better to ask people with deeper understanding of the fs. What I've seen is that in some cases there are extents staying queued for discarding for _too_ long. E.g. reaping a small number of very fat extents keeps delay at max and doesn't allow to reap them effectively. That could be a problem with fast drives. > >> >> Signed-off-by: Pavel Begunkov >> --- >> fs/btrfs/discard.c | 10 +++++----- >> 1 file changed, 5 insertions(+), 5 deletions(-) >> >> diff --git a/fs/btrfs/discard.c b/fs/btrfs/discard.c >> index 741c7e19c32f..76796a90e88d 100644 >> --- a/fs/btrfs/discard.c >> +++ b/fs/btrfs/discard.c >> @@ -519,7 +519,6 @@ void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) >> s64 discardable_bytes; >> u32 iops_limit; >> unsigned long delay; >> - unsigned long lower_limit = BTRFS_DISCARD_MIN_DELAY_MSEC; >> >> discardable_extents = atomic_read(&discard_ctl->discardable_extents); >> if (!discardable_extents) >> @@ -550,11 +549,12 @@ void btrfs_discard_calc_delay(struct btrfs_discard_ctl *discard_ctl) >> >> iops_limit = READ_ONCE(discard_ctl->iops_limit); >> if (iops_limit) >> - lower_limit = max_t(unsigned long, lower_limit, >> - MSEC_PER_SEC / iops_limit); >> + delay = MSEC_PER_SEC / iops_limit; >> + else >> + delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; > > Looks good to me. I wonder why there wasn't handling of if iops_limit > was unfindable > before? Not sure what you mean by unfindable, but async discard is relatively new, might be that everyone just have their hands full. > >> >> - delay = BTRFS_DISCARD_TARGET_MSEC / discardable_extents; >> - delay = clamp(delay, lower_limit, BTRFS_DISCARD_MAX_DELAY_MSEC); >> + delay = clamp(delay, BTRFS_DISCARD_MIN_DELAY_MSEC, >> + BTRFS_DISCARD_MAX_DELAY_MSEC); >> discard_ctl->delay = msecs_to_jiffies(delay); >> >> spin_unlock(&discard_ctl->lock); >> -- >> 2.24.0 >> > > This patch looks all great to me. > > Best regards, > Amy Parker > (they/them) > -- Pavel Begunkov