Subject: Re: UDP regression with packets rates < 10k per sec

From: Eric Dumazet <[email-masked]>
Date: Wed, 09 Sep 2009 17:09:06 +0200

Christoph Lameter a écrit :
> On Wed, 9 Sep 2009, Eric Dumazet wrote:
> 
>> In order to reproduce this here, could you tell me if you use
>>
>> Producer linux-2.6.22 -> Receiver 2.6.22
>> Producer linux-2.6.31 -> Receiver 2.6.31
> 
> I use the above setup.

Then frames are sent on wire but not received

(they are received via  mc loop, internal stack magic)

# ./mcast -L -n1 -r 10000
WARNING: Multiple active ethernet devices. Using local address 192.168.0.1
Receiver: Listening to control channel 239.0.192.1
Receiver: Subscribing to 1 MC addresses 239.0.192-254.2-254 offset 0 origin 192.168.0.1
Sender: Sending 10000 msgs/ch/sec on 1 channels. Probe interval=0.001-1 sec.

TotalMsg   Lost SeqErr TXDrop Msg/Sec  KB/Sec  Min/us  Avg/us  Max/us StdDv
100000      0      0      0   10000  3000.0    7.84    8.89   10.51  0.66

# uname -a
Linux erd 2.6.30.5 #2 SMP Mon Sep 7 17:15:43 CEST 2009 i686 i686 i386 GNU/Linux

I tried an old kernel on same hardware :

# ./mcast -L -n1 -r 10000
WARNING: Multiple active ethernet devices. Using local address 55.225.18.6
Receiver: Listening to control channel 239.0.192.1
Receiver: Subscribing to 1 MC addresses 239.0.192-254.2-254 offset 0 origin 55.225.18.6
Sender: Sending 10000 msgs/ch/sec on 1 channels. Probe interval=0.001-1 sec.

TotalMsg   Lost SeqErr TXDrop Msg/Sec  KB/Sec  Min/us  Avg/us  Max/us StdDv
   99999      0      0      0    9998     0.0    9.00    9.95   14.50  1.56

Linux erd 2.6.9-55.ELsmp #1 SMP Fri Apr 20 17:03:35 EDT 2007 i686 i686 i386 GNU/Linux

So my numbers seem much better than yours...