Re: Huge performance degradation for UDP between 2.4.17 and 2.6

On Sun, 2012-08-05 at 10:16 +0200, LEROY christophe wrote:

Le 02/08/2012 16:13, Eric Dumazet a écrit :

quoted

On Thu, 2012-08-02 at 14:27 +0200, leroy christophe wrote:

quoted

Hi

I'm having a big issue with UDP. Using a powerpc board (MPC860).

With our board running kernel 2.4.17, I'm able to send 160000 voice
packets (UDP, 96 bytes per packet) in 11 seconds.
With the same board running either Kernel 2.6.35.14 or Kernel 3.4.7, I
need 55 seconds to send the same amount of packets.


Is there anything to tune in order to get same output rate as with
Kernel 2.4 ?

kernel size is probably too big for your old / slow cpu.

Maybe you added too many features on your 3.4.7 kernel. (netfilter ?
SLUB debugging ...)

Its hard to say, 2.4.17 had less features and was faster.

Thanks for your answer.
Yes I have netfilter as I need it. However, I tried without it and still 
need about 37 seconds to send the 160000 packets I was sending in 11 
seconds with 2.4.17

I don't think there is any problem with size of the kernel. I still have 
plenty of memory available.

I believe you misunderstood me.

I was referring to cpu caches ( dcache & icache )

All debugging is turned off, and I'm not using SLUB but SLOB.
I have 32Mbytes of RAM. Would SLUB be more performant than SLOB ?

I never used SLOB I cannot comment

Please provide (on 3.4.7)

cat /proc/cpuinfo
lsmod
dmesg