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 15DD1ECAAD3 for ; Tue, 30 Aug 2022 03:19:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229644AbiH3DTi (ORCPT ); Mon, 29 Aug 2022 23:19:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49120 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229447AbiH3DTg (ORCPT ); Mon, 29 Aug 2022 23:19:36 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BFE1FA346B for ; Mon, 29 Aug 2022 20:19:34 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4MGstC3TsbznTgs; Tue, 30 Aug 2022 11:17:07 +0800 (CST) Received: from [10.67.110.25] (10.67.110.25) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 30 Aug 2022 11:19:32 +0800 Message-ID: Date: Tue, 30 Aug 2022 11:19:24 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.1.2 Subject: Re: [PATCH] sched/fair: limit burst to zero when cfs bandwidth is toggled off To: , , , , , , , , , , , , , , CC: References: <20220809120320.19496-1-zhaowenhui8@huawei.com> From: "zhaowenhui (A)" In-Reply-To: <20220809120320.19496-1-zhaowenhui8@huawei.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.110.25] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpemm500022.china.huawei.com (7.185.36.162) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/8/9 20:03, Zhao Wenhui 写道: > When the quota value in CFS bandwidth is set to -1, that imples the > cfs bandwidth is toggled off. So the burst feature is supposed to > be disable as well. > > Currently, when quota is -1, burst will not be check, so that it can be > set to almost arbitery value. Examples: > mkdir /sys/fs/cgroup/cpu/test > echo -1 > /sys/fs/cgroup/cpu/test/cpu.cfs_quota_us > echo 10000000000000000 > /sys/fs/cgroup/cpu/test/cpu.cfs_burst_us > > Moreover, after the burst modified by this way, quota can't be set > to any value: > echo 100000 > cpu.cfs_quota_us > -bash: echo: write error: Invalid argument > > This patch can ensure the burst value being zero and unalterable, > when quota is set to -1. > > Fixes: f4183717b370 ("sched/fair: Introduce the burstable CFS controller") > Reported-by: Zhao Gongyi > Signed-off-by: Zhao Wenhui > --- > kernel/sched/core.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index ee28253c9ac0..4c1fc01d8c68 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -10584,6 +10584,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota, > burst + quota > max_cfs_runtime)) > return -EINVAL; > > + /* > + * Ensure burst equals to zero when quota is -1. > + */ > + if (quota == RUNTIME_INF && burst) > + return -EINVAL; > + > /* > * Prevent race between setting of cfs_rq->runtime_enabled and > * unthrottle_offline_cfs_rqs(). > @@ -10643,8 +10649,10 @@ static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us) > > period = ktime_to_ns(tg->cfs_bandwidth.period); > burst = tg->cfs_bandwidth.burst; > - if (cfs_quota_us < 0) > + if (cfs_quota_us < 0) { > quota = RUNTIME_INF; > + burst = 0; > + } > else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC) > quota = (u64)cfs_quota_us * NSEC_PER_USEC; > else Gentle ping. Thanks, Zhao Wenhui