From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Gushchin Subject: [PATCH] cgroup: document cgroup v2 freezer interface Date: Mon, 12 Nov 2018 15:04:16 -0800 Message-ID: <20181112230422.5911-2-guro@fb.com> References: <20181112230422.5911-1-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=4w/uS5CdZfUu32Qk39NtHIWDaBjSkhBcPb+FbjjLeZ4=; b=s1RIXgb3b+vXc5c89w24eOfcjmq9stBNrOwsuwcbhG9TyvKyMIw0z5/w5SCfK4ZFxR YDhm1UYvp7mmOJ+5vmN2WDG+abzd+uo2KIuR84P8HT92DH/jFnwA4ngNNtUC8cK24umN cR8Pie8hNyZOIQKHYDUvZP3Bc9drjlXrxw4Ev0YJkGZrvJdx6PvERxFYJmo6w7/r/bbj NexQouHzH9t3y2zfNs0UgMl8V6+O3lxko6nbpqJtSxor9uqSsncKIEjByKD7JjDtto6w +xj0+7cyIzPxIQvsxzh0pzAClsudMgWWBplzdhCaf/XaAtWON7+JKfWZw1J2Im77UCut Bw8g== In-Reply-To: <20181112230422.5911-1-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 Cc: Oleg Nesterov , cgroups@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 --- Documentation/admin-guide/cgroup-v2.rst | 26 +++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 184193bcb262..a065c0bed88c 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -862,6 +862,8 @@ 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". @@ -895,6 +897,30 @@ 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 the process + is complete, the "frozen" value in the cgroup.events control file + will be updated and the corresponding notification will be issued. + + Cgroup can be frozen either by its own settings, either 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, either if freezing of the cgroup races with fork(). + If a cgroup is moved to a frozen cgroup, it stops. If a process is + moving 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