Re: [PATCH [RT] 11/14] optimize the !printk fastpath through the lock acquisition

[Andi Kleen]

On Thursday 21 February 2008 16:27:22 Gregory Haskins wrote:

> @@ -660,12 +660,12 @@ rt_spin_lock_fastlock(struct rt_mutex *lock,
>  		void fastcall (*slowfn)(struct rt_mutex *lock))
>  {
>  	/* Temporary HACK! */
> -	if (!current->in_printk)
> -		might_sleep();
> -	else if (in_atomic() || irqs_disabled())
> +	if (unlikely(current->in_printk) && (in_atomic() || irqs_disabled()))

I have my doubts that gcc will honor unlikelies that don't affect
the complete condition of an if.

Also conditions guarding returns are by default predicted unlikely
anyways AFAIK. 

The patch is likely a nop.

-Andi
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/