diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2011-06-17 15:42:38 +0200 |
|---|---|---|
| committer | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2015-12-23 23:36:30 +0100 |
| commit | b09caeac9218201421094f159cb9188046f3e2eb (patch) | |
| tree | 26a88ba6ea263810bf575d8fbb5713d8806ef88e /lib | |
| parent | 50f4955308dad08da9ba05ea3e86031d4d048592 (diff) | |
Intrduce migrate_disable() + cpu_light()
Introduce migrate_disable(). The task can't be pushed to another CPU but can
be preempted.
From: Peter Zijlstra <a.p.zijlstra@chello.nl>:
|Make migrate_disable() be a preempt_disable() for !rt kernels. This
|allows generic code to use it but still enforces that these code
|sections stay relatively small.
|
|A preemptible migrate_disable() accessible for general use would allow
|people growing arbitrary per-cpu crap instead of clean these things
|up.
From: Steven Rostedt <rostedt@goodmis.org>
| The migrate_disable() can cause a bit of a overhead to the RT kernel,
| as changing the affinity is expensive to do at every lock encountered.
| As a running task can not migrate, the actual disabling of migration
| does not need to occur until the task is about to schedule out.
|
| In most cases, a task that disables migration will enable it before
| it schedules making this change improve performance tremendously.
On top of this build get/put_cpu_light(). It is similar to get_cpu():
it uses migrate_disable() instead of preempt_disable(). That means the user
remains on the same CPU but the function using it may be preempted and
invoked again from another caller on the same CPU.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/smp_processor_id.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c index 1afec32de6f2..11fa431046a8 100644 --- a/lib/smp_processor_id.c +++ b/lib/smp_processor_id.c @@ -39,8 +39,9 @@ notrace static unsigned int check_preemption_disabled(const char *what1, if (!printk_ratelimit()) goto out_enable; - printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n", - what1, what2, preempt_count() - 1, current->comm, current->pid); + printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x %08x] code: %s/%d\n", + what1, what2, preempt_count() - 1, __migrate_disabled(current), + current->comm, current->pid); print_symbol("caller is %s\n", (long)__builtin_return_address(0)); dump_stack(); |