4.7 vs 5.2.1 SMP/UP bridging performance

[John Baldwin]

On Tuesday 04 May 2004 03:55 pm, Gerrit Nagelhout wrote:
> Hi,
>
> For one of our applications in our testlab, we are running bridge(4)
> with several user land applications.  I have found that the bridging
> performance (64 byte packets, 2-port bridge) on 5.2.1 is
> significantly lower than that of RELENG_4, especially when running in
> SMP.  The platform is a dual 2.8GHz xeon with a dual port em (100MHz
> PCI-X).  Invariants are disabled, and polling (with idle_polling
> enabled) is used.

Well, I do have a patch you can try but I am unsure if it will help or not.  
Basically, the new interrupt code in 5.2 has a bug that can really hurt 
interrupt latency when doing kernel-intensive tasks.  Since you are using 
polling it may not help much, but it's still something you can try.  The 
patch should apply to 5.2.1 just fine.

http://www.FreeBSD.org/~jhb/patches/ithread_preempt.patch

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org