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author | Tejun Heo <tj@kernel.org> | 2010-05-06 18:49:21 +0200 |
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committer | Tejun Heo <tj@kernel.org> | 2010-05-06 18:49:21 +0200 |
commit | 969c79215a35b06e5e3efe69b9412f858df7856c (patch) | |
tree | 4256378687c8bc2011ec35a3e28bc3b6473e912c /kernel/rcutorture.c | |
parent | stop_machine: reimplement using cpu_stop (diff) | |
download | linux-969c79215a35b06e5e3efe69b9412f858df7856c.tar.xz linux-969c79215a35b06e5e3efe69b9412f858df7856c.zip |
sched: replace migration_thread with cpu_stop
Currently migration_thread is serving three purposes - migration
pusher, context to execute active_load_balance() and forced context
switcher for expedited RCU synchronize_sched. All three roles are
hardcoded into migration_thread() and determining which job is
scheduled is slightly messy.
This patch kills migration_thread and replaces all three uses with
cpu_stop. The three different roles of migration_thread() are
splitted into three separate cpu_stop callbacks -
migration_cpu_stop(), active_load_balance_cpu_stop() and
synchronize_sched_expedited_cpu_stop() - and each use case now simply
asks cpu_stop to execute the callback as necessary.
synchronize_sched_expedited() was implemented with private
preallocated resources and custom multi-cpu queueing and waiting
logic, both of which are provided by cpu_stop.
synchronize_sched_expedited_count is made atomic and all other shared
resources along with the mutex are dropped.
synchronize_sched_expedited() also implemented a check to detect cases
where not all the callback got executed on their assigned cpus and
fall back to synchronize_sched(). If called with cpu hotplug blocked,
cpu_stop already guarantees that and the condition cannot happen;
otherwise, stop_machine() would break. However, this patch preserves
the paranoid check using a cpumask to record on which cpus the stopper
ran so that it can serve as a bisection point if something actually
goes wrong theree.
Because the internal execution state is no longer visible,
rcu_expedited_torture_stats() is removed.
This patch also renames cpu_stop threads to from "stopper/%d" to
"migration/%d". The names of these threads ultimately don't matter
and there's no reason to make unnecessary userland visible changes.
With this patch applied, stop_machine() and sched now share the same
resources. stop_machine() is faster without wasting any resources and
sched migration users are much cleaner.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Josh Triplett <josh@freedesktop.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Diffstat (limited to 'kernel/rcutorture.c')
-rw-r--r-- | kernel/rcutorture.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcutorture.c b/kernel/rcutorture.c index 58df55bf83ed..2b676f3a0f26 100644 --- a/kernel/rcutorture.c +++ b/kernel/rcutorture.c @@ -669,7 +669,7 @@ static struct rcu_torture_ops sched_expedited_ops = { .sync = synchronize_sched_expedited, .cb_barrier = NULL, .fqs = rcu_sched_force_quiescent_state, - .stats = rcu_expedited_torture_stats, + .stats = NULL, .irq_capable = 1, .name = "sched_expedited" }; |