- The hierarchy of cpusets can be mounted at /dev/cpuset, for
browsing and manipulation from user space.
- A cpuset may be marked exclusive, which ensures that no other
- cpuset (except direct ancestors and descendents) may contain
+ cpuset (except direct ancestors and descendants) may contain
any overlapping CPUs or Memory Nodes.
- You can list all the tasks (by pid) attached to any cpuset.
--------------------------------
If a cpuset is cpu or mem exclusive, no other cpuset, other than
-a direct ancestor or descendent, may share any of the same CPUs or
+a direct ancestor or descendant, may share any of the same CPUs or
Memory Nodes.
A cpuset that is mem_exclusive *or* mem_hardwall is "hardwalled",
When doing this, you don't usually want to leave any unpinned tasks in
the top cpuset that might use non-trivial amounts of CPU, as such tasks
may be artificially constrained to some subset of CPUs, depending on
-the particulars of this flag setting in descendent cpusets. Even if
+the particulars of this flag setting in descendant cpusets. Even if
such a task could use spare CPU cycles in some other CPUs, the kernel
scheduler might not consider the possibility of load balancing that
task to that underused CPU.
Of course it takes some searching cost to find movable tasks and/or
idle CPUs, the scheduler might not search all CPUs in the domain
-everytime. In fact, in some architectures, the searching ranges on
+every time. In fact, in some architectures, the searching ranges on
events are limited in the same socket or node where the CPU locates,
-while the load balance on tick searchs all.
+while the load balance on tick searches all.
For example, assume CPU Z is relatively far from CPU X. Even if CPU Z
is idle while CPU X and the siblings are busy, scheduler can't migrate
of MPOL_BIND nodes are still allowed in the new cpuset. If the task
was using MPOL_BIND and now none of its MPOL_BIND nodes are allowed
in the new cpuset, then the task will be essentially treated as if it
-was MPOL_BIND bound to the new cpuset (even though its numa placement,
+was MPOL_BIND bound to the new cpuset (even though its NUMA placement,
as queried by get_mempolicy(), doesn't change). If a task is moved
from one cpuset to another, then the kernel will adjust the tasks
memory placement, as above, the next time that the kernel attempts
# /bin/echo 1-4 > cpus -> set cpus list to cpus 1,2,3,4
# /bin/echo 1,2,3,4 > cpus -> set cpus list to cpus 1,2,3,4
+To add a CPU to a cpuset, write the new list of CPUs including the
+CPU to be added. To add 6 to the above cpuset:
+
+# /bin/echo 1-4,6 > cpus -> set cpus list to cpus 1,2,3,4,6
+
+Similarly to remove a CPU from a cpuset, write the new list of CPUs
+without the CPU to be removed.
+
+To remove all the CPUs:
+
+# /bin/echo "" > cpus -> clear cpus list
+
2.3 Setting flags
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