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Tue, 27 May 2025 09:05:51 +0000 (GMT) From: Vishal Chourasia To: Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Jonathan Corbet , cgroups@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Vishal Chourasia Subject: [PATCH] Documentation: cgroup: clarify controller enabling semantics Date: Tue, 27 May 2025 14:23:36 +0530 Message-ID: <20250527085335.256045-2-vishalc@linux.ibm.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: XAUiHN1XPtjLl4fF0KJuMAJtifm6UvN7 X-Proofpoint-GUID: XAUiHN1XPtjLl4fF0KJuMAJtifm6UvN7 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTI3MDA3MyBTYWx0ZWRfX8Ss8AJaVoXnE wAssbYWwVmyXrn9j0/D9t5hquiuwJlDqlJkA65m2DxfH6S92hh809trgSjlIFbcfhCmgTQZu9gU 3rZ/+icwA3/Nd++GcUtGCSOisnuUYXxmoXw0JV8Uy5FNdrlIerj5GcIHPZr984brDbxaZmZ4/ZN 2yqWas1jzMfXvPdtrBiCOmindH2DZzDb/74/UZFU3Nh9XcaB2ELb5JmCoJx3nWom+6qpkYVPp9x QZ3Z6nmKOXy/nrNhOPnlq8HMdCh3B/xH04lFipioVNTOu91vrn81z5i25/q92A7/9u7rPtFCxf3 5e+DkWsTPq/fSd57ByBzq3NwQZMZ8jyvCgdvCht8pirIwq9pKz84MpYEaBHtTbZYbhIP2aYidwQ 0CICP9T2UquAXETtcIm284Pzwy34RFusA4xcnhUEXK1ccL/6yf2YuE2yyk31gjJcQ00eXje4 X-Authority-Analysis: v=2.4 cv=fJM53Yae c=1 sm=1 tr=0 ts=68358073 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=dt9VzEwgFbYA:10 a=VnNF1IyMAAAA:8 a=a_b_lNqkOoIFiPTXujYA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-27_04,2025-05-26_02,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 spamscore=0 priorityscore=1501 bulkscore=0 adultscore=0 mlxlogscore=847 suspectscore=0 phishscore=0 clxscore=1015 lowpriorityscore=0 malwarescore=0 impostorscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505160000 definitions=main-2505270073 The documentation for cgroup controller management has been updated to be more consistent regarding following concepts: What does it mean to have controllers 1) available in a cgroup, vs. 2) enabled in a cgroup Which has been clearly defined below in the documentation. "Enabling a controller in a cgroup indicates that the distribution of the target resource across its immediate children will be controlled. Consider the following sub-hierarchy" As an example, consider /sys/fs/cgroup # cat cgroup.controllers cpuset cpu io memory hugetlb pids misc /sys/fs/cgroup # cat cgroup.subtree_control # No controllers by default /sys/fs/cgroup # echo +cpu +memory > cgroup.subtree_control /sys/fs/cgroup # cat cgroup.subtree_control cpu memory # cpu and memory enabled in /sys/fs/cgroup /sys/fs/cgroup # mkdir foo_cgrp /sys/fs/cgroup # cd foo_cgrp/ /sys/fs/cgroup/foo_cgrp # cat cgroup.controllers cpu memory # cpu and memory available in 'foo_cgrp' /sys/fs/cgroup/foo_cgrp # cat cgroup.subtree_control # empty by default /sys/fs/cgroup/foo_cgrp # ls cgroup.controllers cpu.max.burst memory.numa_stat cgroup.events cpu.pressure memory.oom.group cgroup.freeze cpu.stat memory.peak cgroup.kill cpu.stat.local memory.pressure cgroup.max.depth cpu.weight memory.reclaim cgroup.max.descendants cpu.weight.nice memory.stat cgroup.pressure io.pressure memory.swap.current cgroup.procs memory.current memory.swap.events cgroup.stat memory.events memory.swap.high cgroup.subtree_control memory.events.local memory.swap.max cgroup.threads memory.high memory.swap.peak cgroup.type memory.low memory.zswap.current cpu.idle memory.max memory.zswap.max cpu.max memory.min memory.zswap.writeback Once a controller is available in a cgroup it can be used to resource control processes of the cgroup. Signed-off-by: Vishal Chourasia --- Documentation/admin-guide/cgroup-v2.rst | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 1a16ce68a4d7..0e1686511c45 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -438,8 +438,8 @@ Controlling Controllers Enabling and Disabling ~~~~~~~~~~~~~~~~~~~~~~ -Each cgroup has a "cgroup.controllers" file which lists all -controllers available for the cgroup to enable:: +Each cgroup has a cgroup.controllers file, which lists all the controllers +available for that cgroup and which can be enabled for its children. # cat cgroup.controllers cpu io memory -- 2.49.0