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 9651CC77B7F for ; Fri, 5 May 2023 13:36:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232636AbjEENf7 (ORCPT ); Fri, 5 May 2023 09:35:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232531AbjEENf6 (ORCPT ); Fri, 5 May 2023 09:35:58 -0400 Received: from mail-pf1-x42d.google.com (mail-pf1-x42d.google.com [IPv6:2607:f8b0:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D4D9622694 for ; Fri, 5 May 2023 06:35:27 -0700 (PDT) Received: by mail-pf1-x42d.google.com with SMTP id d2e1a72fcca58-63b5465fc13so1398579b3a.3 for ; Fri, 05 May 2023 06:35:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1683293727; x=1685885727; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=g3RvOc3E8ZFO1x/9akr2bpEbHeCFqf25nGHeEQGUAU0=; b=C0II2oek0zykI2dzG8RkjOqVTRnziAg3YOlg88doaFXBlEhJiIQLAg034eFtxiz6vS g4J8GzDJnyaqmfq8f7Z0i//CSTfgoxZmlub414QeBnfVUF727nol+9PHR2yR/xbSMxlC o6lH+wAATQI69r76wyrPRw2nujuAx8X1wObPJk0sgB3Vz/JHn+/j7XfVEKvs6waccDv/ CdMFmqpzeiZ/fuPIhmQYLumv7uRuc7NYm7B7r0Pqre1WB3dgAeBFdvOU/ayOFBBfZ+tn VfmjJuCKHmz5I3ZOVgB6eu0R670bvCMWjW2HF8jSwPMJdkvUVsLONN0m2u73Yc+tOvpQ 7C9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683293727; x=1685885727; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=g3RvOc3E8ZFO1x/9akr2bpEbHeCFqf25nGHeEQGUAU0=; b=RXIQ8hCOff8vQDYUsen3e1r4X4Mr9yNTFFvX1MbOPKefvlUP82yLBmlZH2WDjTzkcF qACwSu6o6llgSXkx2PQus4kiLFITQ2tg2l+wy5xfSN6yVO2nAUJ8PYTIQPJjeKLhTeFs 3EvFfzq7YsRQJGEgw7Z3774gMBQXEWs5cZqePRycbS+Ocxjf1TwTvQMzgobwK026CMLq hInFv2fncQyjSA13neCe/p2smDAnZkSdGdxcGJF5BHslnc620ZwIfhbJQYhD2UK9ugOu NGTKDkcykzxboHSx5hotUqNB5S7Z9ACCBw4i6PCFNvRg8EDGEsP/4vyehs8ABSSV0rmW b+zA== X-Gm-Message-State: AC+VfDySdb16e6WSiSdYUJRS0M3L1OP/45Iw6dxuUu9bY/0YZKh3bDCt 16w2Ghu+5lewuC0zNFWvmRgT7YxyfAP+A4RiOC7fzQ== X-Google-Smtp-Source: ACHHUZ7gQMBNAALjAbEgOqi206u0+0pNQfoKvfAbpiw5YTqHAEfnb7ItjMX7kIvFewN7aqFaOrs/fQ== X-Received: by 2002:a05:6a00:1ad0:b0:63b:5f78:d6db with SMTP id f16-20020a056a001ad000b0063b5f78d6dbmr2357743pfv.21.1683293727288; Fri, 05 May 2023 06:35:27 -0700 (PDT) Received: from [10.254.14.195] ([139.177.225.238]) by smtp.gmail.com with ESMTPSA id y17-20020aa78051000000b0062d859a33d1sm1650787pfm.84.2023.05.05.06.35.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 05 May 2023 06:35:26 -0700 (PDT) Message-ID: <6696100e-e838-d96a-2894-bbca9783d2a3@bytedance.com> Date: Fri, 5 May 2023 21:35:21 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [External] Re: [PATCH v2] blk-throttle: Fix io statistics for cgroup v1 To: Andrea Righi Cc: tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20230401094708.77631-1-hanjinke.666@bytedance.com> From: hanjinke In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 在 2023/5/5 上午5:13, Andrea Righi 写道: > On Thu, May 04, 2023 at 11:08:53PM +0800, hanjinke wrote: >> Hi >> >> Sorry for delay（Chinese Labor Day holiday). > > No problem, it was also Labor Day in Italy. :) > >> >> 在 2023/4/29 上午3:05, Andrea Righi 写道: >>> On Sat, Apr 01, 2023 at 05:47:08PM +0800, Jinke Han wrote: >>>> From: Jinke Han >>>> >>>> After commit f382fb0bcef4 ("block: remove legacy IO schedulers"), >>>> blkio.throttle.io_serviced and blkio.throttle.io_service_bytes become >>>> the only stable io stats interface of cgroup v1, and these statistics >>>> are done in the blk-throttle code. But the current code only counts the >>>> bios that are actually throttled. When the user does not add the throttle >>>> limit, the io stats for cgroup v1 has nothing. I fix it according to the >>>> statistical method of v2, and made it count all ios accurately. >>>> >>>> Fixes: a7b36ee6ba29 ("block: move blk-throtl fast path inline") >>>> Signed-off-by: Jinke Han >>> >>> Thanks for fixing this! >>> >>> The code looks correct to me, but this seems to report io statistics >>> only if at least one throttling limit is defined. IIRC with cgroup v1 it >>> was possible to see the io statistics inside a cgroup also with no >>> throttling limits configured. >>> >>> Basically to restore the old behavior we would need to drop the >>> cgroup_subsys_on_dfl() check, something like the following (on top of >>> your patch). >>> >>> But I'm not sure if we're breaking other behaviors in this way... >>> opinions? >>> >>> block/blk-cgroup.c | 3 --- >>> block/blk-throttle.h | 12 +++++------- >>> 2 files changed, 5 insertions(+), 10 deletions(-) >>> >>> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >>> index 79138bfc6001..43af86db7cf3 100644 >>> --- a/block/blk-cgroup.c >>> +++ b/block/blk-cgroup.c >>> @@ -2045,9 +2045,6 @@ void blk_cgroup_bio_start(struct bio *bio) >>> struct blkg_iostat_set *bis; >>> unsigned long flags; >>> - if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) >>> - return; >>> - >>> /* Root-level stats are sourced from system-wide IO stats */ >>> if (!cgroup_parent(blkcg->css.cgroup)) >>> return; >>> diff --git a/block/blk-throttle.h b/block/blk-throttle.h >>> index d1ccbfe9f797..bcb40ee2eeba 100644 >>> --- a/block/blk-throttle.h >>> +++ b/block/blk-throttle.h >>> @@ -185,14 +185,12 @@ static inline bool blk_should_throtl(struct bio *bio) >>> struct throtl_grp *tg = blkg_to_tg(bio->bi_blkg); >>> int rw = bio_data_dir(bio); >>> - if (!cgroup_subsys_on_dfl(io_cgrp_subsys)) { >>> - if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { >>> - bio_set_flag(bio, BIO_CGROUP_ACCT); >>> - blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf, >>> - bio->bi_iter.bi_size); >>> - } >>> - blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1); >>> + if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { >>> + bio_set_flag(bio, BIO_CGROUP_ACCT); >>> + blkg_rwstat_add(&tg->stat_bytes, bio->bi_opf, >>> + bio->bi_iter.bi_size); >>> } >>> + blkg_rwstat_add(&tg->stat_ios, bio->bi_opf, 1); >> I checked the code again. If we remove cgroup_subsys_on_dfl check here, io statistics will still be performed in the case of v2, which I think is unnecessary, and this information will be counted to io_service_bytes/io_serviced, these two files are not visible in v2. Am I missing something? Thanks. Jinke