Re: [PATCH] rtmutex: ensure only the top waiter or higher priority task can take the lock and reduce unrelated boosting

Lai Jiangshan
2010-12-15T14:30:15Z

On Wed, Dec 15, 2010 at 8:07 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Wed, 15 Dec 2010, Lai Jiangshan wrote:
>> +     if (waiter || rt_mutex_has_waiters(lock)) {
>> +             unsigned long flags;
>> +             struct rt_mutex_waiter *top;
>> +
>> +             raw_spin_lock_irqsave(&task->pi_lock, flags);
>> +
>> +             /* remove the queued waiter. */
>> +             if (waiter) {
>> +                     plist_del(&waiter->list_entry, &lock->wait_list);
>> +                     task->pi_blocked_on = NULL;
>> +             }
>> +
>> +             /*
>> +              * We have to enqueue the top waiter(if have) into
>> +              * task->pi_waiters list and would get boost from it.
>
> No, we don't get boosted from it. We just have to enqueue it into
> pi_waiters list. There is no boosting happening at this point. Please
> be very careful with the comments in this code.
>
> Otherwise this looks really interesting. Still this wants to be ported
> to -rt and stress tested there.
>

Hi, Thomas,

Where can I find the code of stress testcases?

Thanks,
Lai