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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DBB1C4321E for ; Wed, 30 Nov 2022 21:09:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229601AbiK3VJ1 (ORCPT ); Wed, 30 Nov 2022 16:09:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44360 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229770AbiK3VJX (ORCPT ); Wed, 30 Nov 2022 16:09:23 -0500 Received: from mail-pg1-x530.google.com (mail-pg1-x530.google.com [IPv6:2607:f8b0:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 92E0288B4F; Wed, 30 Nov 2022 13:09:22 -0800 (PST) Received: by mail-pg1-x530.google.com with SMTP id f3so17243439pgc.2; Wed, 30 Nov 2022 13:09:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=7v4d6zaC4L81hfiBNb2Cor9kyL3VqKmV3/kGNvOemQ4=; b=KkQfDW/gc08jpOQwU7UFqMKS7YNnQ9pn2xJKWk1O/71hBqhVuZvr0RPB+dmEmUL5ye xDpaMQ4XhbVldeIM5DIbTL0SLuUc1TY8tpvitVtwhxyYnuHHzufMBZLcTM0uWv4mUKg9 WcjfkyG6DzHJOhP3nUpI7C0Kx9TooMPDylwUQ2yRjIsK4pbudxvzTQZYkV3I75xd38c8 39fm+Z7m1U8xCTByy7ZY4l0ggq7zbR9Ilgwl6I/3X8P20eJd+68SaFY3ySEWh0o8/tZb V5X8HJayccgkIWTrGUSa2b0gTfKURFTnRcDDQ0h8qJqJV31igDseAKynOE7XcHHBW9Sn eXIA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=7v4d6zaC4L81hfiBNb2Cor9kyL3VqKmV3/kGNvOemQ4=; b=jrO45cxDPOSn4/0pGRbkIGjsrGpRZ2GgLKRxGwtSXQKBmarXCEb3nw7zLQHEL2D3AO AR1tceYa9wf8xL36mVJ0KLZKqR40aXdG/s6s/RdQadluPszjftS2b4mzKXUCDck3q2rc cm9qrXP00YmDZQj08HcpN7cxCY/Efo9VJPonn9FwY0SONM2wKI4Sk8XkbqeQPpt3jkOJ p5tp52czK1+5WJJKQQDCWQpzOu54POFSrpRw9LXoK13BMibcFsSGdcJoDAm0G8gbHu85 j9BRg03S03uyljkjBARgvNRO8gzQomrTNzQ0gfGRRYOdFbMGxUqzdSwHXc9QgJNjB0mP +wpg== X-Gm-Message-State: ANoB5pmiy+HiWUiV2DhMWT1muG8NNQn8lwNh1OXYMsXqza7L9QlbcV5z HBnW2ba9xUByITQRmjKDACo= X-Google-Smtp-Source: AA0mqf727J+qaCOMRUQATA0i/21bN+qxdroHDJhyjdFZ3e6lTo6Xn5AhSo1sN4FwwsiuajQVHmnPAA== X-Received: by 2002:a63:525e:0:b0:477:bca8:1cd9 with SMTP id s30-20020a63525e000000b00477bca81cd9mr31590682pgl.581.1669842562016; Wed, 30 Nov 2022 13:09:22 -0800 (PST) Received: from localhost (2603-800c-1a02-1bae-a7fa-157f-969a-4cde.res6.spectrum.com. [2603:800c:1a02:1bae:a7fa:157f:969a:4cde]) by smtp.gmail.com with ESMTPSA id z17-20020aa79e51000000b0056c3d3f5a8dsm1812338pfq.56.2022.11.30.13.09.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Nov 2022 13:09:21 -0800 (PST) Sender: Tejun Heo Date: Wed, 30 Nov 2022 11:09:20 -1000 From: Tejun Heo To: Kemeng Shi Cc: josef@toxicpanda.com, axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 02/10] blk-throttle: Fix that bps of child could exceed bps limited in parent Message-ID: References: <20221129030147.27400-1-shikemeng@huawei.com> <20221129030147.27400-3-shikemeng@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221129030147.27400-3-shikemeng@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Nov 29, 2022 at 11:01:39AM +0800, Kemeng Shi wrote: > Consider situation as following (on the default hierarchy): > HDD > | > root (bps limit: 4k) > | > child (bps limit :8k) > | > fio bs=8k > Rate of fio is supposed to be 4k, but result is 8k. Reason is as > following: > Size of single IO from fio is larger than bytes allowed in one > throtl_slice in child, so IOs are always queued in child group first. > When queued IOs in child are dispatched to parent group, BIO_BPS_THROTTLED > is set and these IOs will not be limited by tg_within_bps_limit anymore. > Fix this by only set BIO_BPS_THROTTLED when the bio traversed the entire > tree. > > There patch has no influence on situation which is not on the default > hierarchy as each group is a single root group without parent. > > Signed-off-by: Kemeng Shi Acked-by: Tejun Heo -- tejun