diff options
Diffstat (limited to 'Documentation/admin-guide/cgroup-v2.rst')
| -rw-r--r-- | Documentation/admin-guide/cgroup-v2.rst | 73 |
1 files changed, 42 insertions, 31 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index f67c0829350b..4ef890191196 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -1213,23 +1213,25 @@ PAGE_SIZE multiple when read back. A read-write single value file which exists on non-root cgroups. The default is "max". - Memory usage throttle limit. This is the main mechanism to - control memory usage of a cgroup. If a cgroup's usage goes + Memory usage throttle limit. If a cgroup's usage goes over the high boundary, the processes of the cgroup are throttled and put under heavy reclaim pressure. Going over the high limit never invokes the OOM killer and - under extreme conditions the limit may be breached. + under extreme conditions the limit may be breached. The high + limit should be used in scenarios where an external process + monitors the limited cgroup to alleviate heavy reclaim + pressure. memory.max A read-write single value file which exists on non-root cgroups. The default is "max". - Memory usage hard limit. This is the final protection - mechanism. If a cgroup's memory usage reaches this limit and - can't be reduced, the OOM killer is invoked in the cgroup. - Under certain circumstances, the usage may go over the limit - temporarily. + Memory usage hard limit. This is the main mechanism to limit + memory usage of a cgroup. If a cgroup's memory usage reaches + this limit and can't be reduced, the OOM killer is invoked in + the cgroup. Under certain circumstances, the usage may go + over the limit temporarily. In default configuration regular 0-order allocations always succeed unless OOM killer chooses current task as a victim. @@ -1238,10 +1240,6 @@ PAGE_SIZE multiple when read back. Caller could retry them differently, return into userspace as -ENOMEM or silently ignore in cases like disk readahead. - This is the ultimate protection mechanism. As long as the - high limit is used and monitored properly, this limit's - utility is limited to providing the final safety net. - memory.reclaim A write-only nested-keyed file which exists for all cgroups. @@ -1582,6 +1580,13 @@ PAGE_SIZE multiple when read back. Healthy workloads are not expected to reach this limit. + memory.swap.peak + A read-only single value file which exists on non-root + cgroups. + + The max swap usage recorded for the cgroup and its + descendants since the creation of the cgroup. + memory.swap.max A read-write single value file which exists on non-root cgroups. The default is "max". @@ -2024,31 +2029,33 @@ that attribute: no-change Do not modify the I/O priority class. - none-to-rt - For requests that do not have an I/O priority class (NONE), - change the I/O priority class into RT. Do not modify - the I/O priority class of other requests. + promote-to-rt + For requests that have a non-RT I/O priority class, change it into RT. + Also change the priority level of these requests to 4. Do not modify + the I/O priority of requests that have priority class RT. restrict-to-be For requests that do not have an I/O priority class or that have I/O - priority class RT, change it into BE. Do not modify the I/O priority - class of requests that have priority class IDLE. + priority class RT, change it into BE. Also change the priority level + of these requests to 0. Do not modify the I/O priority class of + requests that have priority class IDLE. idle Change the I/O priority class of all requests into IDLE, the lowest I/O priority class. + none-to-rt + Deprecated. Just an alias for promote-to-rt. + The following numerical values are associated with the I/O priority policies: -+-------------+---+ -| no-change | 0 | -+-------------+---+ -| none-to-rt | 1 | -+-------------+---+ -| rt-to-be | 2 | -+-------------+---+ -| all-to-idle | 3 | -+-------------+---+ ++----------------+---+ +| no-change | 0 | ++----------------+---+ +| rt-to-be | 2 | ++----------------+---+ +| all-to-idle | 3 | ++----------------+---+ The numerical value that corresponds to each I/O priority class is as follows: @@ -2064,9 +2071,13 @@ The numerical value that corresponds to each I/O priority class is as follows: The algorithm to set the I/O priority class for a request is as follows: -- Translate the I/O priority class policy into a number. -- Change the request I/O priority class into the maximum of the I/O priority - class policy number and the numerical I/O priority class. +- If I/O priority class policy is promote-to-rt, change the request I/O + priority class to IOPRIO_CLASS_RT and change the request I/O priority + level to 4. +- If I/O priorityt class is not promote-to-rt, translate the I/O priority + class policy into a number, then change the request I/O priority class + into the maximum of the I/O priority class policy number and the numerical + I/O priority class. PID --- @@ -2439,7 +2450,7 @@ Miscellaneous controller provides 3 interface files. If two misc resources (res_ res_b 10 misc.current - A read-only flat-keyed file shown in the non-root cgroups. It shows + A read-only flat-keyed file shown in the all cgroups. It shows the current usage of the resources in the cgroup and its children.:: $ cat misc.current |