linux-toradex.git/Documentation/cpu-hotplug.txt, branch v2.6.25-rc2

[S390] Get rid of additional_cpus kernel parameter.

2008-01-26T13:11:15+00:00

It caused only a lot of confusion. From now on cpu hotplug of up to
NR_CPUS will work by default. If somebody wants to limit that then
the possible_cpus parameter can be used.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()

2008-01-25T20:08:02+00:00

Replace all lock_cpu_hotplug/unlock_cpu_hotplug from the kernel and use
get_online_cpus and put_online_cpus instead as it highlights the
refcount semantics in these operations.

The new API guarantees protection against the cpu-hotplug operation, but
it doesn't guarantee serialized access to any of the local data
structures. Hence the changes needs to be reviewed.

In case of pseries_add_processor/pseries_remove_processor, use
cpu_maps_update_begin()/cpu_maps_update_done() as we're modifying the
cpu_present_map there.

Signed-off-by: Gautham R Shenoy 
Signed-off-by: Ingo Molnar

hotplug cpu: migrate a task within its cpuset

2007-10-19T18:53:44+00:00

When a cpu is disabled, move_task_off_dead_cpu() is called for tasks that have
been running on that cpu.

Currently, such a task is migrated:
 1) to any cpu on the same node as the disabled cpu, which is both online
    and among that task's cpus_allowed
 2) to any cpu which is both online and among that task's cpus_allowed

It is typical of a multithreaded application running on a large NUMA system to
have its tasks confined to a cpuset so as to cluster them near the memory that
they share.  Furthermore, it is typical to explicitly place such a task on a
specific cpu in that cpuset.  And in that case the task's cpus_allowed
includes only a single cpu.

This patch would insert a preference to migrate such a task to some cpu within
its cpuset (and set its cpus_allowed to its entire cpuset).

With this patch, migrate the task to:
 1) to any cpu on the same node as the disabled cpu, which is both online
    and among that task's cpus_allowed
 2) to any online cpu within the task's cpuset
 3) to any cpu which is both online and among that task's cpus_allowed

In order to do this, move_task_off_dead_cpu() must make a call to
cpuset_cpus_allowed_locked(), a new subset of cpuset_cpus_allowed(), that will
not block.  (name change - per Oleg's suggestion)

Calls are made to cpuset_lock() and cpuset_unlock() in migration_call() to set
the cpuset mutex during the whole migrate_live_tasks() and
migrate_dead_tasks() procedure.

[akpm@linux-foundation.org: build fix]
[pj@sgi.com: Fix indentation and spacing]
Signed-off-by: Cliff Wickman 
Cc: Oleg Nesterov 
Cc: Christoph Lameter 
Cc: Paul Jackson 
Cc: Ingo Molnar 
Signed-off-by: Paul Jackson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Add suspend-related notifications for CPU hotplug

2007-05-09T19:30:56+00:00

Since nonboot CPUs are now disabled after tasks and devices have been
frozen and the CPU hotplug infrastructure is used for this purpose, we need
special CPU hotplug notifications that will help the CPU-hotplug-aware
subsystems distinguish normal CPU hotplug events from CPU hotplug events
related to a system-wide suspend or resume operation in progress.  This
patch introduces such notifications and causes them to be used during
suspend and resume transitions.  It also changes all of the
CPU-hotplug-aware subsystems to take these notifications into consideration
(for now they are handled in the same way as the corresponding "normal"
ones).

[oleg@tv-sign.ru: cleanups]
Signed-off-by: Rafael J. Wysocki 
Cc: Gautham R Shenoy 
Cc: Pavel Machek 
Signed-off-by: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Fix typos in /Documentation : Misc

2006-11-30T04:21:10+00:00

This patch fixes typos in various Documentation txts. The patch addresses some
misc words.

Signed-off-by: Matt LaPlante 
Acked-by: Randy Dunlap 
Signed-off-by: Adrian Bunk

[PATCH] doc: fixing cpu-hotplug documentation

2006-10-20T17:26:43+00:00

Fixing cpu-hotplug documentation as follows:

 - moving confusing asterisk on additional_cpus descrition
 - fixing some typos
 - unifying indentation for source code and command line example

Signed-off-by: Satoru Takeuchi 
Cc: Ashok Raj 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] cpu hotplug: fix hotplug cpu documentation for proper usage

2006-07-31T20:28:39+00:00

Update hotplug cpu documentation to clearly state when to use
register_cpu_notifier() and register_hotcpu_notifier.

Signed-off-by: Chandra Seetharaman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] for_each_possible_cpu: documentaion

2006-03-28T17:16:05+00:00

Replace for_each_cpu with for_each_possible_cpu.

Modifies occurences in documentaion.

for_each_cpu in whatisRCU.txt should be for_each_online_cpu ???
(I'm not sure..)

Signed-off-by: KAMEZAWA Hiroyuki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] cpu hotplug documentation fix

2006-02-21T04:00:10+00:00

Looks like there was a merge conflict when patches
8f8b1138fc9f65e3591aac83a4ee394fef34ac1d and
255acee706b333b79f593dd366f16e1f107cccc3 were applied which wasn't properly
resolved. Fix this and add some additional description.

Signed-off-by: Heiko Carstens 
Cc: Ashok Raj 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] s390: possible_cpus parameter

2006-02-17T21:59:27+00:00

Introduce possible_cpus command line option.  Hard sets the number of bits set
in cpu_possible_map.  Unlike the additional_cpus parameter this one guarantees
that num_possible_cpus() will stay constant even if the system gets rebooted
and a different number of cpus are present at startup.

Signed-off-by: Heiko Carstens 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds