From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C36062F12BA for ; Fri, 27 Feb 2026 08:18:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772180320; cv=none; b=d9tlGUnXV4GGvEtxy+UrGf8IgvoHSYRpDlN3pbAmmmoBTukj4m2DK4f14NHyoNICOUQDQzx4fHKdwAxufVwrtWg4oIjheCcNWr1K9P7aaq5aS/34+EFfSSCzq/lpmbUdcI3Yb+f/ROUDFkzRpAXwG9gdp9YoftznXY2FU9s77aQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772180320; c=relaxed/simple; bh=wYLDKPo49cItC3U3+d2G1yV0W8YqXauHN90xtsK/ESc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aGVfzV4D8nMnOVqg5DobqLRteML2VpPizPz5MnOYU7qlh4K4xgdiastFGe8dOvCB3c/vGNjuCe2Tmdx2wGDHlMsIGFsWvp0p+s90Cl6VK+e1/dKOtMEJjAdSL6uOTHVEiJJhvN2EQ0Z3u1XS30ytEvfdtVieENWdMz2GXVMF+Jg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.177]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4fMh673PnFzYQv57 for ; Fri, 27 Feb 2026 16:18:07 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 46ADD4058D for ; Fri, 27 Feb 2026 16:18:34 +0800 (CST) Received: from [10.67.111.176] (unknown [10.67.111.176]) by APP4 (Coremail) with SMTP id gCh0CgCnCPlYU6FphYW4Iw--.19665S2; Fri, 27 Feb 2026 16:18:34 +0800 (CST) Message-ID: <025660e0-aacd-4ea7-a4e5-11990d2145d3@huaweicloud.com> Date: Fri, 27 Feb 2026 16:18:32 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND] In cgroup v2, setting a smaller value for sched_rt_runtime_us fails. To: Chen Jinghuang , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot Cc: Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org References: <20260226033839.129431-1-chenjinghuang2@huawei.com> Content-Language: en-US From: Chen Ridong In-Reply-To: <20260226033839.129431-1-chenjinghuang2@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgCnCPlYU6FphYW4Iw--.19665S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ZF4rJw17Zw17tryxZr4UXFb_yoW8Zr18pr WDXay5Aan5t3WIgasrAr9ruFyrW3yfJ3W7tr97J3yxJrnF9r1qgw4vq34jqa1jgryfGFy7 JFn09r9xKayjgF7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUv0b4IE77IF4wAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxkF7I0En4kS 14v26r1q6r43MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I 8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8 ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x 0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU1 7KsUUUUUU== X-CM-SenderInfo: hfkh02xlgr0w46kxt4xhlfz01xgou0bp/ On 2026/2/26 11:38, Chen Jinghuang wrote: > For example: > > # cat /proc/sys/kernel/sched_rt_runtime_us > 950000 > # echo 940000 > /proc/sys/kernel/sched_rt_runtime_us > -bash: echo: write error: Invalid argument > > This occurs because when the global RT quota is reduced while the root > cgroup’s ratio remains unchanged, the root cgroup’s proportion ends up > exceeding the global RT ratio. This is unreasonable: the root cgroup’s > ratio should be updated when the global RT ratio changes. > > This patch ensures the root cgroup’s RT quota is adjusted whenever the > global RT quota is modified. > > Signed-off-by: Chen Ridong > Signed-off-by: Chen Jinghuang > --- > kernel/sched/rt.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index f1867fe8e5c5..30770ba7be4e 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -2814,9 +2814,11 @@ long sched_group_rt_period(struct task_group *tg) > static int sched_rt_global_constraints(void) > { > int ret = 0; > + u64 period = global_rt_period(); > + u64 runtime = global_rt_runtime(); > > mutex_lock(&rt_constraints_mutex); > - ret = __rt_schedulable(NULL, 0, 0); > + ret = __rt_schedulable(&root_task_group, period, runtime); > mutex_unlock(&rt_constraints_mutex); > > return ret; > @@ -2856,6 +2858,14 @@ static int sched_rt_global_validate(void) > > static void sched_rt_do_global(void) > { > +#ifdef CONFIG_RT_GROUP_SCHED > + if (!rt_group_sched_enabled()) > + return; > + > + WARN_ON_ONCE(tg_set_rt_bandwidth(&root_task_group, > + global_rt_period(), > + global_rt_runtime())); > +#endif > } > > static int sched_rt_handler(const struct ctl_table *table, int write, void *buffer, Reviewed-by: Chen Ridong -- Best regards, Ridong