diff options
Diffstat (limited to 'Documentation/cgroups/blkio-controller.txt')
| -rw-r--r-- | Documentation/cgroups/blkio-controller.txt | 35 |
1 files changed, 24 insertions, 11 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index b4b1fb3a83f0..1b70843c574e 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -94,13 +94,11 @@ Throttling/Upper Limit policy Hierarchical Cgroups ==================== -- Currently none of the IO control policy supports hierarchical groups. But - cgroup interface does allow creation of hierarchical cgroups and internally - IO policies treat them as flat hierarchy. +- Currently only CFQ supports hierarchical groups. For throttling, + cgroup interface does allow creation of hierarchical cgroups and + internally it treats them as flat hierarchy. - So this patch will allow creation of cgroup hierarchcy but at the backend - everything will be treated as flat. So if somebody created a hierarchy like - as follows. + If somebody created a hierarchy like as follows. root / \ @@ -108,16 +106,20 @@ Hierarchical Cgroups | test3 - CFQ and throttling will practically treat all groups at same level. + CFQ will handle the hierarchy correctly but and throttling will + practically treat all groups at same level. For details on CFQ + hierarchy support, refer to Documentation/block/cfq-iosched.txt. + Throttling will treat the hierarchy as if it looks like the + following. pivot / / \ \ root test1 test2 test3 - Down the line we can implement hierarchical accounting/control support - and also introduce a new cgroup file "use_hierarchy" which will control - whether cgroup hierarchy is viewed as flat or hierarchical by the policy.. - This is how memory controller also has implemented the things. + Nesting cgroups, while allowed, isn't officially supported and blkio + genereates warning when cgroups nest. Once throttling implements + hierarchy support, hierarchy will be supported and the warning will + be removed. Various user visible config options =================================== @@ -172,6 +174,12 @@ Proportional weight policy files dev weight 8:16 300 +- blkio.leaf_weight[_device] + - Equivalents of blkio.weight[_device] for the purpose of + deciding how much weight tasks in the given cgroup has while + competing with the cgroup's child cgroups. For details, + please refer to Documentation/block/cfq-iosched.txt. + - blkio.time - disk time allocated to cgroup per device in milliseconds. First two fields specify the major and minor number of the device and @@ -279,6 +287,11 @@ Proportional weight policy files and minor number of the device and third field specifies the number of times a group was dequeued from a particular device. +- blkio.*_recursive + - Recursive version of various stats. These files show the + same information as their non-recursive counterparts but + include stats from all the descendant cgroups. + Throttling/Upper limit policy files ----------------------------------- - blkio.throttle.read_bps_device |