Commit:     8f5aa26c75b7722e80c0c5c5bb833d41865d7019
Parent:     73507f335f406ff31ceb97b39fa76eaee00f4f26
Author:     Paul Jackson <[EMAIL PROTECTED]>
AuthorDate: Thu Feb 7 00:14:48 2008 -0800
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Feb 7 08:42:23 2008 -0800

    cpusets: update_cpumask documentation fix
    Update cpuset documentation to match the October 2007 "Fix cpusets
    update_cpumask" changes that now apply changes to a cpusets 'cpus' allowed
    mask immediately to the cpus_allowed of the tasks in that cpuset.
    Signed-off-by: Paul Jackson <[EMAIL PROTECTED]>
    Acked-by: Cliff Wickman <[EMAIL PROTECTED]>
    Cc: David Rientjes <[EMAIL PROTECTED]>
    Cc: Paul Menage <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
 Documentation/cpusets.txt |   23 ++++++++---------------
 1 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/Documentation/cpusets.txt b/Documentation/cpusets.txt
index 141bef1..43db6fe 100644
--- a/Documentation/cpusets.txt
+++ b/Documentation/cpusets.txt
@@ -523,21 +523,14 @@ from one cpuset to another, then the kernel will adjust 
the tasks
 memory placement, as above, the next time that the kernel attempts
 to allocate a page of memory for that task.
-If a cpuset has its CPUs modified, then each task using that
-cpuset does _not_ change its behavior automatically.  In order to
-minimize the impact on the critical scheduling code in the kernel,
-tasks will continue to use their prior CPU placement until they
-are rebound to their cpuset, by rewriting their pid to the 'tasks'
-file of their cpuset.  If a task had been bound to some subset of its
-cpuset using the sched_setaffinity() call, and if any of that subset
-is still allowed in its new cpuset settings, then the task will be
-restricted to the intersection of the CPUs it was allowed on before,
-and its new cpuset CPU placement.  If, on the other hand, there is
-no overlap between a tasks prior placement and its new cpuset CPU
-placement, then the task will be allowed to run on any CPU allowed
-in its new cpuset.  If a task is moved from one cpuset to another,
-its CPU placement is updated in the same way as if the tasks pid is
-rewritten to the 'tasks' file of its current cpuset.
+If a cpuset has its 'cpus' modified, then each task in that cpuset
+will have its allowed CPU placement changed immediately.  Similarly,
+if a tasks pid is written to a cpusets 'tasks' file, in either its
+current cpuset or another cpuset, then its allowed CPU placement is
+changed immediately.  If such a task had been bound to some subset
+of its cpuset using the sched_setaffinity() call, the task will be
+allowed to run on any CPU allowed in its new cpuset, negating the
+affect of the prior sched_setaffinity() call.
 In summary, the memory placement of a task whose cpuset is changed is
 updated by the kernel, on the next allocation of a page for that task,
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at

Reply via email to