Re: userspace irq balancer

David S. Miller
2003-05-27T00:04:01Z

From: Andrea Arcangeli <andrea@suse.de>
Date: Tue, 27 May 2003 02:06:39 +0200

On Mon, May 26, 2003 at 04:43:00PM -0700, David S. Miller wrote:
> softirq load? How much weight will softirq load get compared to

normally the softirq runs after the hardirq (commoncase) and you want to
run those softirq computations on the idle cpu too (i.e. no userspace
running so offload hardirq and in turn softqirq to it) No difference.
softirq is like hardirq just longer and with hardirq enabled. One more
reason to offload it to an idle cpu.

One hardirq can equate to thousands of packets worth of softirq load,
especially with NAPI. And you cannot even know what this ratio is
(packets processed per hardware IRQ load). It can be anywhere from
1 to 1000. And you absolutely do not want to behave identically
for all such values.

How can you even claim to be taking this into account in a logical
manner if you cannot even tell me how you will determine how much
softirq load is created by a hardware irq?