diff options
| author | Li Zefan <lizf@cn.fujitsu.com> | 2008-09-13 02:33:09 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-09-13 14:41:51 -0700 |
| commit | 024994310e10cd7632f43b6873558820308c1af1 (patch) | |
| tree | 8afc91968962ce0adc322e6763b99df3fc70a41e /Documentation/cpusets.txt | |
| parent | 4e74339af6a59c061cf02f1ac497766bca1de19a (diff) | |
cpuset: hotplug documentation fix
If all the cpus in a cpuset are offlined, the tasks in it will be moved to
the nearest ancestor with non-empty cpus.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Jackson <pj@sgi.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/cpusets.txt')
| -rw-r--r-- | Documentation/cpusets.txt | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt index 1f5a924d1e5..47e568a9370 100644 --- a/Documentation/cpusets.txt +++ b/Documentation/cpusets.txt @@ -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. |