irq: Set CPU affinity right on thread creation

As irq_thread_check_affinity is called ONLY inside the while loop in
the irq thread, the core affinity is set only when an interrupt
occurs. This patch sets the core affinity right after the irq thread
is created and before it waits for interrupts. In real-tiime targets
that do not typically change the core affinity of irqs during
run-time, this patch will save additional latency of an irq thread in
setting the core affinity during the first interrupt occurrence for
that irq.

Signed-off-by: Sankara S Muthukrishnan <sankara.m@ni.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/CAFQPvXeVZ858WFYimEU5uvLNxLDd6bJMmqWihFmbCf3ntokz0A@mail.gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index d06a396c7ce3ad0848771838a7cad9963c3a9438..1cbd572f6ad8d474ccf4859a4f9a7b677773a2ea 100644 (file)
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -849,6 +849,8 @@ static int irq_thread(void *data)
        init_task_work(&on_exit_work, irq_thread_dtor);
        task_work_add(current, &on_exit_work, false);
 
+       irq_thread_check_affinity(desc, action);
+
        while (!irq_wait_for_interrupt(action)) {
                irqreturn_t action_ret;