question about softirqs

[Chris Friesen]

Andi Kleen wrote:
> Thomas Gleixner <tglx at linutronix.de> writes:

>>Err, no. Chris is completely correct:
>>
>>        if (!in_interrupt())
>>		wakeup_softirqd();
> 
> Yes you have to wake it up just in case, but it doesn't normally
> process the data because a normal softirq comes in faster. It's
> just a safety policy. 

What about the scenario I raised earlier, where we have incoming network
packets, no hardware interrupts coming in other than the timer tick, and
a high-priority userspace app is spinning on recvmsg() with MSG_DONTWAIT
set?

As far as I can tell, in this scenario softirqs may not get processed on
return from a syscall (contradicting the documentation).  In the worst
case, they may not get processed until the next timer tick.

Chris