From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Gushchin Subject: [PATCH v4 7/7] cgroup: document cgroup v2 freezer interface Date: Fri, 30 Nov 2018 15:47:45 -0800 Message-ID: <20181130234745.6756-8-guro@fb.com> References: <20181130234745.6756-1-guro@fb.com> Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=DNiXMipqkuH/anRcfopn8XxqISAUbvZjEb9Ku6rCx0A=; b=ZeLS648n7PDoTv4CN/31oK5h1LPX+aZPSGwD9mC96VTyLO2yq9pyNveFAVz14beil1 fueDRtMVCVuoSImhu35O/Muj29FSM4uHGe6ByeUwTadsPjG+xUpcc9k+iBwOwrYc0LIB Ra0Z7SfUi34PS5Wqjnm7euwgQUmKefATVZ4IFg1W7Tj9GNasW6bPxue/9HhHqanhyayG 1j7fu5ew3wBQqJR3S/rhhYGe3kV96H1FbsjZfslZJlnyHJxgcZPVifqdED3ipFAAotEC l3DD+7W/Nds21wS409N02ShTyTXDE7OZQl3LHefE6gwFF3buYc3tDRY30bQYqkDSNfDu mL2w== In-Reply-To: <20181130234745.6756-1-guro@fb.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tejun Heo , Oleg Nesterov Cc: Dan Carpenter , Mike Rapoport , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Roman Gushchin Describe cgroup v2 freezer interface in the cgroup v2 admin guide. Signed-off-by: Roman Gushchin Cc: Tejun Heo Cc: linux-doc@vger.kernel.org Cc: kernel-team@fb.com --- Documentation/admin-guide/cgroup-v2.rst | 27 +++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 07e06136a550..f8335e26b362 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -864,6 +864,8 @@ All cgroup core files are prefixed with "cgroup." populated 1 if the cgroup or its descendants contains any live processes; otherwise, 0. + frozen + 1 if the cgroup is frozen; otherwise, 0. cgroup.max.descendants A read-write single value files. The default is "max". @@ -897,6 +899,31 @@ All cgroup core files are prefixed with "cgroup." A dying cgroup can consume system resources not exceeding limits, which were active at the moment of cgroup deletion. + cgroup.freeze + A read-write single value file which exists on non-root cgroups. + Allowed values are "0" and "1". The default is "0". + + Writing "1" to the file causes freezing of the cgroup and all + descendant cgroups. This means that all belonging processes will + be stopped and will not run until the cgroup will be explicitly + unfrozen. Freezing of the cgroup may take some time; when this action + is completed, the "frozen" value in the cgroup.events control file + will be updated to "1" and the corresponding notification will be + issued. + + A cgroup can be frozen either by its own settings, or by settings + of any ancestor cgroups. If any of ancestor cgroups is frozen, the + cgroup will remain frozen. + + Processes in the frozen cgroup can be killed by a fatal signal. + They also can enter and leave a frozen cgroup: either by an explicit + move by a user, or if freezing of the cgroup races with fork(). + If a process is moved to a frozen cgroup, it stops. If a process is + moved out of a frozen cgroup, it becomes running. + + Frozen status of a cgroup doesn't affect any cgroup tree operations: + it's possible to delete a frozen (and empty) cgroup, as well as + create new sub-cgroups. Controllers =========== -- 2.17.2