Re: [v4.1.10-rt10][PATCH 1/2] genirq: introduce new generic_handle_irq_rt_wa() api

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 11/03/2015 08:51 PM, Thomas Gleixner wrote:
>> where MAX_MSI_IRQS = 32 now, but potentially can be increased up to 256.
> 
> And you really oversimplified the code above. The reality is:
> 
>     for (i = 0; i < MAX_MSI_CTRLS: i++) {
>     	u32 status = read_msi_ctrl(i);
> 
> 	for_each_bit(status)
> 		handle_irq();
>     }
> 
> So sure, the worst case here is MAX_MSI_CTRLS * 32, but if all
> possible 256 MSI interrupts are pending at the same time, you have
> other problems than that.

With threaded interrupts we would have 256 invocations of
wake_up_process() so nothing should take ages.

> Thanks,
> 
> 	tglx

Sebastian