diff options
Diffstat (limited to 'Documentation/cpusets.txt')
| -rw-r--r-- | Documentation/cpusets.txt | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt index 1f5a924d1e5..5c86c258c79 100644 --- a/Documentation/cpusets.txt +++ b/Documentation/cpusets.txt @@ -48,7 +48,7 @@ hooks, beyond what is already present, required to manage dynamic job placement on large systems. Cpusets use the generic cgroup subsystem described in -Documentation/cgroup.txt. +Documentation/cgroups/cgroups.txt. Requests by a task, using the sched_setaffinity(2) system call to include CPUs in its CPU affinity mask, and using the mbind(2) and @@ -635,14 +635,16 @@ prior 'mems' setting, will not be moved. There is an exception to the above. If hotplug functionality is used to remove all the CPUs that are currently assigned to a cpuset, -then the kernel will automatically update the cpus_allowed of all -tasks attached to CPUs in that cpuset to allow all CPUs. When memory -hotplug functionality for removing Memory Nodes is available, a -similar exception is expected to apply there as well. In general, -the kernel prefers to violate cpuset placement, over starving a task -that has had all its allowed CPUs or Memory Nodes taken offline. User -code should reconfigure cpusets to only refer to online CPUs and Memory -Nodes when using hotplug to add or remove such resources. +then all the tasks in that cpuset will be moved to the nearest ancestor +with non-empty cpus. But the moving of some (or all) tasks might fail if +cpuset is bound with another cgroup subsystem which has some restrictions +on task attaching. In this failing case, those tasks will stay +in the original cpuset, and the kernel will automatically update +their cpus_allowed to allow all online CPUs. When memory hotplug +functionality for removing Memory Nodes is available, a similar exception +is expected to apply there as well. In general, the kernel prefers to +violate cpuset placement, over starving a task that has had all +its allowed CPUs or Memory Nodes taken offline. There is a second exception to the above. GFP_ATOMIC requests are kernel internal allocations that must be satisfied, immediately. |