Workqueues queues work on current cpu, if the caller haven't passed a preferred
cpu. This may wake up an idle CPU, which is actually not required.
This work can be processed by any CPU and so we must select a non-idle CPU here.
This patch adds in support in workqueue framework to get preferred CPU details
from the scheduler, instead of using current CPU.
Most of the time when a work is queued, the current cpu isn't idle and so we
will choose it only. There are cases when a cpu is idle when it queues some
work. For example, consider following scenario:
- A cpu has programmed a timer and is IDLE now.
- CPU gets into interrupt handler due to timer and queues a work. As the CPU is
currently IDLE, we can queue this work to some other CPU.
Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
---
kernel/workqueue.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 042d221..d32efa2 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1238,7 +1238,7 @@ static void __queue_work(unsigned int cpu, struct
workqueue_struct *wq,
struct global_cwq *last_gcwq;
if (cpu == WORK_CPU_UNBOUND)
- cpu = raw_smp_processor_id();
+ cpu = sched_select_cpu(0);
/*
* It's multi cpu. If @work was previously on a different
@@ -1383,7 +1383,7 @@ static void __queue_delayed_work(int cpu, struct
workqueue_struct *wq,
if (gcwq)
lcpu = gcwq->cpu;
if (lcpu == WORK_CPU_UNBOUND)
- lcpu = raw_smp_processor_id();
+ lcpu = sched_select_cpu(0);
} else {
lcpu = WORK_CPU_UNBOUND;
}
--
1.7.12.rc2.18.g61b472e
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