Re: NAPI Race?

[David S. Miller]

On 08 Oct 2003 14:17:31 -0700
Marko Rauhamaa <marko@xxxxxxxxxx> wrote:

> But do_softirq() explicitly refuses to run
> the same softirq right away.

Check current 2.6.x sources, it does loop a certain number of times
even for the same softirq type.

> Well, it almost does. You can blast a NAPI driver with a packet flood,
> and the system is happy and responsive -- no interrupts are generated,
> and packets are polled by ksoftirqd. However, you can find a packet rate
> that will cause the CPU to spend virtually all of its time in NAPI.

This situation can be created with non-NAPI drivers too.

Alexey is trying to explain to you what the true cause of the
problem is, and it's not NAPI, it's softirq starvation.
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