From nobody Sun Feb 8 23:06:55 2026 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (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 B28A769DFB; Fri, 19 Apr 2024 09:05:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.255 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713517542; cv=none; b=A2qlxunDI2ewc6AiCuP/ZHeYciyS/qhkJaXdNHEQWHcc5Z4gqAWGkfd5jjEAGxLcN280W+81NExTRef3W9WH+bMSxzcxyTreqV2Z2TZFnOSnBNlIdHAjEbQKnEAZpwGn6dAl3saywew34+D7gQMD+nBdGtnJ1oOffuCb5B4CIxU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713517542; c=relaxed/simple; bh=3F263T9DjJp6sF8LRqG6ccucwjDKAexzal9qHEK3RWE=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=rr11mlU7BFWbSy6bTOoVTQdVRKvrMPMn6f+lvVGtHyQXy21M2vjGXIMTIJM+V6aIAmltCKbYQT/FkOBJNDgjzcYDUPNvIfmPHajK21aaS4zp6Ae4gM5QZHwr2zIO2JuiDQqLADFg5698B37j0qKWhziFC4AiykzemazSEQ8TJ4E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.255 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4VLTDx5GkHz1N8Qd; Fri, 19 Apr 2024 17:02:41 +0800 (CST) Received: from canpemm500001.china.huawei.com (unknown [7.192.104.163]) by mail.maildlp.com (Postfix) with ESMTPS id 7B50B18006D; Fri, 19 Apr 2024 17:05:31 +0800 (CST) Received: from octopus.huawei.com (10.67.174.191) by canpemm500001.china.huawei.com (7.192.104.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Fri, 19 Apr 2024 17:05:31 +0800 From: Zhang Qiao To: , , , , CC: , , Zhang Qiao Subject: [PATCH v2] sched/Documentation: Add RT_RUNTIME_SHARE documentation Date: Fri, 19 Apr 2024 17:04:32 +0800 Message-ID: <20240419090432.1935211-1-zhangqiao22@huawei.com> X-Mailer: git-send-email 2.18.0.huawei.25 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500001.china.huawei.com (7.192.104.163) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" RT_RUNTIME_SHARE is an important strategy for rt bandwidth, and we should document this sched feature. Signed-off-by: Zhang Qiao Improvements-suggested-by: Bagas Sanjaya Reviewed-by: Bagas Sanjaya --- Documentation/scheduler/sched-rt-group.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/Documentation/scheduler/sched-rt-group.rst b/Documentation/sch= eduler/sched-rt-group.rst index d685609ed3d7..eea2fc6f068f 100644 --- a/Documentation/scheduler/sched-rt-group.rst +++ b/Documentation/scheduler/sched-rt-group.rst @@ -12,6 +12,7 @@ Real-Time group scheduling 2.1 System-wide settings 2.2 Default behaviour 2.3 Basis for grouping tasks + 2.4 RT_RUNTIME_SHARE sched feature 3. Future plans =20 =20 @@ -146,6 +147,17 @@ For now, this can be simplified to just the following = (but see Future plans): =20 \Sum_{i} runtime_{i} <=3D global_runtime =20 +2.4 RT_RUNTIME_SHARE sched feature +---------------------------------- + +RT_RUNTIME_SHARE allows a cpu to borrow rt-runtime from other cpus if it r= uns +out of its own rt-runtime. + +With this feature enabled, a rt-task may hit 100% cpu usage and can stall = other +per-cpu tasks like kworkers, as a result, which leads into system hang. + +Thus, it is advised to disable this feature by default to avoid aforementi= oned +issue unless you know what you're doing. =20 3. Future plans =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D --=20 2.18.0.huawei.25