diff options
author | Cliff Wickman <cpw@sgi.com> | 2007-10-19 06:40:46 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-19 18:53:44 (GMT) |
commit | 470fd646444c65a5d062a371f5ec8dcedee61239 (patch) | |
tree | 59b923486d4a95efa07c4b2ad7cb0b1fcc3f3c88 /kernel/cpuset.c | |
parent | bd89aabc6761de1c35b154fe6f914a445d301510 (diff) | |
download | linux-fsl-qoriq-470fd646444c65a5d062a371f5ec8dcedee61239.tar.xz |
hotplug cpu: migrate a task within its cpuset
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 <cpw@sgi.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/cpuset.c')
-rw-r--r-- | kernel/cpuset.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c index fa31cb9..50f5dc4 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1818,10 +1818,23 @@ cpumask_t cpuset_cpus_allowed(struct task_struct *tsk) cpumask_t mask; mutex_lock(&callback_mutex); + mask = cpuset_cpus_allowed_locked(tsk); + mutex_unlock(&callback_mutex); + + return mask; +} + +/** + * cpuset_cpus_allowed_locked - return cpus_allowed mask from a tasks cpuset. + * Must be called with callback_mutex held. + **/ +cpumask_t cpuset_cpus_allowed_locked(struct task_struct *tsk) +{ + cpumask_t mask; + task_lock(tsk); guarantee_online_cpus(task_cs(tsk), &mask); task_unlock(tsk); - mutex_unlock(&callback_mutex); return mask; } |