Re: [patch] softirq performance fixes, cleanups, 2.4.10.

[Andrea Arcangeli]

On Fri, Sep 28, 2001 at 06:46:16PM +0200, Ingo Molnar wrote:
> 
> On Fri, 28 Sep 2001, Andrea Arcangeli wrote:
> 
> > he's allowing to repeat the loop more than once to hide it, [...]
> 
> it's not done to 'hide' it in any way. I removed the mask method because
> it's redundant under the new scheme.

What you are missing is a property provided by the old method.

We have the NET_RX_SOFTIRQ that floods very heavily, so far so good.

Then we have HI_SOFTIRQ, incidentally HI_SOFTIRQ from irq wants to be
executed with very low latency, with your patch it _can_ be postpone to
ksoftirqd processing just because there's the NET_RX_SOFTIRQ cpu hog in
background. With the old method it was guaranteed that the HI_SOFTIRQ
was executed with very low latency within the irq, no matter of the
NET_RX_SOFTIRQ flood.

So there _is_ a difference, and the multiple-loop will tend to "hide"
the difference.

Andrea