linux-toradex.git/include/linux/stop_machine.h, branch v2.6.38.6

stopmachine: Define __stop_machine when CONFIG_STOP_MACHINE=n

2010-10-14T06:55:28+00:00

Define dummy __stop_machine() function even when
CONFIG_STOP_MACHINE=n. This getcpu-required version of
stop_machine() will be used from poke_text_smp().

Signed-off-by: Masami Hiramatsu 
Acked-by: Tejun Heo 
Cc: Rusty Russell 
Cc: Ananth N Mavinakayanahalli 
Cc: 2nddept-manager@sdl.hitachi.co.jp
Cc: Peter Zijlstra 
LKML-Reference: <20101014031030.4100.34156.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Ingo Molnar

cpu_stop: add dummy implementation for UP

2010-05-08T15:12:33+00:00

When !CONFIG_SMP, cpu_stop functions weren't defined at all which
could lead to build failures if UP code uses cpu_stop facility.  Add
dummy cpu_stop implementation for UP.  The waiting variants execute
the work function directly with preempt disabled and
stop_one_cpu_nowait() schedules a workqueue work.

Makefile and ifdefs around stop_machine implementation are updated to
accomodate CONFIG_SMP && !CONFIG_STOP_MACHINE case.

Signed-off-by: Tejun Heo 
Reported-by: Ingo Molnar

stop_machine: reimplement using cpu_stop

2010-05-06T16:49:20+00:00

Reimplement stop_machine using cpu_stop.  As cpu stoppers are
guaranteed to be available for all online cpus,
stop_machine_create/destroy() are no longer necessary and removed.

With resource management and synchronization handled by cpu_stop, the
new implementation is much simpler.  Asking the cpu_stop to execute
the stop_cpu() state machine on all online cpus with cpu hotplug
disabled is enough.

stop_machine itself doesn't need to manage any global resources
anymore, so all per-instance information is rolled into struct
stop_machine_data and the mutex and all static data variables are
removed.

The previous implementation created and destroyed RT workqueues as
necessary which made stop_machine() calls highly expensive on very
large machines.  According to Dimitri Sivanich, preventing the dynamic
creation/destruction makes booting faster more than twice on very
large machines.  cpu_stop resources are preallocated for all online
cpus and should have the same effect.

Signed-off-by: Tejun Heo 
Acked-by: Rusty Russell 
Acked-by: Peter Zijlstra 
Cc: Oleg Nesterov 
Cc: Dimitri Sivanich

cpu_stop: implement stop_cpu[s]()

2010-05-06T16:49:20+00:00

Implement a simplistic per-cpu maximum priority cpu monopolization
mechanism.  A non-sleeping callback can be scheduled to run on one or
multiple cpus with maximum priority monopolozing those cpus.  This is
primarily to replace and unify RT workqueue usage in stop_machine and
scheduler migration_thread which currently is serving multiple
purposes.

Four functions are provided - stop_one_cpu(), stop_one_cpu_nowait(),
stop_cpus() and try_stop_cpus().

This is to allow clean sharing of resources among stop_cpu and all the
migration thread users.  One stopper thread per cpu is created which
is currently named "stopper/CPU".  This will eventually replace the
migration thread and take on its name.

* This facility was originally named cpuhog and lived in separate
  files but Peter Zijlstra nacked the name and thus got renamed to
  cpu_stop and moved into stop_machine.c.

* Better reporting of preemption leak as per Peter's suggestion.

Signed-off-by: Tejun Heo 
Acked-by: Peter Zijlstra 
Cc: Oleg Nesterov 
Cc: Dimitri Sivanich

stop_machine: introduce stop_machine_create/destroy.

2009-01-04T22:10:14+00:00

Introduce stop_machine_create/destroy. With this interface subsystems
that need a non-failing stop_machine environment can create the
stop_machine machine threads before actually calling stop_machine.
When the threads aren't needed anymore they can be killed with
stop_machine_destroy again.

When stop_machine gets called and the threads aren't present they
will be created and destroyed automatically. This restores the old
behaviour of stop_machine.

This patch also converts cpu hotplug to the new interface since it
is special: cpu_down calls __stop_machine instead of stop_machine.
However the kstop threads will only be created when stop_machine
gets called.

Changing the code so that the threads would be created automatically
on __stop_machine is currently not possible: when __stop_machine gets
called we hold cpu_add_remove_lock, which is the same lock that
create_rt_workqueue would take. So the workqueue needs to be created
before the cpu hotplug code locks cpu_add_remove_lock.

Signed-off-by: Heiko Carstens 
Signed-off-by: Rusty Russell

cpumask: convert rest of files in kernel/

2008-12-31T23:42:28+00:00

Impact: Reduce stack usage, use new cpumask API.

Mainly changing cpumask_t to 'struct cpumask' and similar simple API
conversion.  Two conversions worth mentioning:

1) we use cpumask_any_but to avoid a temporary in kernel/softlockup.c,
2) Use cpumask_var_t in taskstats_user_cmd().

Signed-off-by: Rusty Russell 
Signed-off-by: Mike Travis 
Cc: Balbir Singh 
Cc: Ingo Molnar

stop_machine: Remove deprecated stop_machine_run

2008-08-25T14:19:27+00:00

Everyone should be using stop_machine() now.  The staged API
transition helped life in linux-next.

Signed-off-by: Rusty Russell

stop_machine(): stop_machine_run() changed to use cpu mask

2008-07-28T02:16:30+00:00

Instead of a "cpu" arg with magic values NR_CPUS (any cpu) and ~0 (all
cpus), pass a cpumask_t.  Allow NULL for the common case (where we
don't care which CPU the function is run on): temporary cpumask_t's
are usually considered bad for stack space.

This deprecates stop_machine_run, to be removed soon when all the
callers are dead.

Signed-off-by: Rusty Russell

Simplify stop_machine

2008-07-28T02:16:29+00:00

stop_machine creates a kthread which creates kernel threads.  We can
create those threads directly and simplify things a little.  Some care
must be taken with CPU hotunplug, which has special needs, but that code
seems more robust than it was in the past.

Signed-off-by: Rusty Russell 
Acked-by: Christian Borntraeger

stop_machine: add ALL_CPUS option

2008-07-28T02:16:28+00:00

-allow stop_mahcine_run() to call a function on all cpus. Calling
 stop_machine_run() with a 'ALL_CPUS' invokes this new behavior.
 stop_machine_run() proceeds as normal until the calling cpu has
 invoked 'fn'. Then, we tell all the other cpus to call 'fn'.

Signed-off-by: Jason Baron 
Signed-off-by: Mathieu Desnoyers 
Signed-off-by: Rusty Russell 
CC: Adrian Bunk 
CC: Andi Kleen 
CC: Alexey Dobriyan 
CC: Christoph Hellwig 
CC: mingo@elte.hu
CC: akpm@osdl.org