On 2013/7/30 1:19, Abbas Raza wrote:
> From: Abbas Raza <abbas_r...@mentor.com>
>
> wait_task_inactive shouldn't be called in kthread_bind for presmp
> initcalls the same way it is done in !SMP case.
>
> more info here:
> http://permalink.gmane.org/gmane.linux.kernel.embedded/4046
>
> This patch improves boot time for pre-smp initcalls as given below
>
> initcall spawn_ksoftirqd+0x0/0x54 returned 0 after 0 usecs
> initcall init_workqueues+0x0/0x358 returned 0 after 0 usecs
> initcall cpu_stop_init+0x0/0xcc returned 0 after 0 usecs
>
> boot time without this patch:
>
> initcall spawn_ksoftirqd+0x0/0x54 returned 0 after 9765 usecs
> initcall init_workqueues+0x0/0x358 returned 0 after 9765 usecs
> initcall cpu_stop_init+0x0/0xcc returned 0 after 19531 usecs
>
> Signed-off-by: Abbas Raza <abbas_r...@mentor.com>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Ingo Molnar <mi...@redhat.com>
>
> ---
> kernel/kthread.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/kthread.c b/kernel/kthread.c
> index b579af5..80f19b5 100644
> --- a/kernel/kthread.c
> +++ b/kernel/kthread.c
> @@ -221,10 +221,15 @@ EXPORT_SYMBOL(kthread_create_on_node);
> */
> void kthread_bind(struct task_struct *p, unsigned int cpu)
> {
> - /* Must have done schedule() in kthread() before we set_task_cpu */
> - if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
> - WARN_ON(1);
> - return;
Hi Abbas, this patch isn't based the current mainline, and kthread_bind()
has been changed since v3.9.
> + if (!((num_online_cpus() == 1) && !cpu)) {
> + /*
> + * Must have done schedule() in kthread() before
> + * we set_task_cpu
> + */
> + if (!wait_task_inactive(p, TASK_UNINTERRUPTIBLE)) {
> + WARN_ON(1);
> + return;
> + }
> }
>
> /* It's safe because the task is inactive. */
>
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