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Subjectvoluntary-preempt- seems to lose UDP messages.

I have a real-time application that transmits 20 MBytes/s over UDP/Gigabit
Ethernet between 2 PCs. The NICs are from Intel and use the e1000 driver
(MTU=1500). On the receive side, the computer has to process the data (real-time
tasks doing signal processing work and using up 50% of the CPU time).

This app works OK with 2.6.7 and : the app does not complain about lost

But when I use the voluntary-preemt- patch on the receiving PC, the
app starts complaining about lost messages. And also, netstat -s -u shows that
lots of UDP packets are lost (on the PC that receives the data).
[root@centaurus root]# netstat -u -s
8433 packets received
0 packets to unknown port received.
869 packet receive errors
366 packets sent

I have already retried with the e1000 parameters RxIntDelay=0 and
RxDescriptors=1024. This did not improve anything.

Note: I don't see any error message with dmesg nor in /var/log/messages.

I find the voluntary-preempt series very important and would really like it to
make its way into the stock kernel. I would therefore gladly make additional
tests to help you find the problem. Please give me directions.

thanks for your help,

P.O. Gaillard

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