>From 760824d48d8a1f302b80367681ada19836d93521 Mon Sep 17 00:00:00 2001
From: Tejun Heo <t...@kernel.org>
Date: Tue, 18 Sep 2012 12:48:43 -0700
The existing work_on_cpu() implementation is hugely inefficient. It
creates a new kthread, execute that single function and then let the
kthread die on each invocation.
Now that system_wq can handle concurrent executions, there's no
advantage of doing this. Reimplement work_on_cpu() using system_wq
which makes it simpler and way more efficient.
Signed-off-by: Tejun Heo <t...@kernel.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Jiri Kosina <jkos...@suse.cz>
Cc: Bjorn Helgaas <bhelg...@google.com>
Cc: Len Brown <l...@kernel.org>
Cc: Rafael J. Wysocki <r...@sisk.pl>
---
Applying to wq/for-3.7.
Thanks.
kernel/workqueue.c | 25 ++++++++-----------------
1 files changed, 8 insertions(+), 17 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 3e324aa..737ab01 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3624,18 +3624,17 @@ static int __cpuinit workqueue_cpu_down_callback(struct
notifier_block *nfb,
#ifdef CONFIG_SMP
struct work_for_cpu {
- struct completion completion;
+ struct work_struct work;
long (*fn)(void *);
void *arg;
long ret;
};
-static int do_work_for_cpu(void *_wfc)
+static void work_for_cpu_fn(struct work_struct *work)
{
- struct work_for_cpu *wfc = _wfc;
+ struct work_for_cpu *wfc = container_of(work, struct work_for_cpu,
work);
+
wfc->ret = wfc->fn(wfc->arg);
- complete(&wfc->completion);
- return 0;
}
/**
@@ -3650,19 +3649,11 @@ static int do_work_for_cpu(void *_wfc)
*/
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
{
- struct task_struct *sub_thread;
- struct work_for_cpu wfc = {
- .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion),
- .fn = fn,
- .arg = arg,
- };
+ struct work_for_cpu wfc = { .fn = fn, .arg = arg };
- sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu");
- if (IS_ERR(sub_thread))
- return PTR_ERR(sub_thread);
- kthread_bind(sub_thread, cpu);
- wake_up_process(sub_thread);
- wait_for_completion(&wfc.completion);
+ INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
+ schedule_work_on(cpu, &wfc.work);
+ flush_work(&wfc.work);
return wfc.ret;
}
EXPORT_SYMBOL_GPL(work_on_cpu);
--
1.7.7.3
--
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