Messages in this thread | | | Date | Wed, 15 Oct 2003 16:13:31 -0400 | From | Chris Friesen <> | Subject | Re: question on incoming packets and scheduler |
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Davide Libenzi wrote: > On Wed, 15 Oct 2003, Chris Friesen wrote:
>>It appears that 2.4.20 fixes this issue, but there is another one >>remaining that the latency appears to be dependent on the number of >>incoming packets. See thread "incoming packet latency in 2.4.[18-20]" >>for details. This behaviour doesn't show up in 2.6, and I'm about to >>test 2.4.22.
> Are you sure it's not a livelock issue during the burst?
I dunno, you tell me.
The test app simply sits in select() until a packet comes in, then it spins on recvmsg() until there are no more messages. It uses SO_TIMESTAMP to find out when the packet got to the kernel, and does a gettimeofday() right after the recvmsg(), then calculates the delta for each packet and the overall average.
With 2.4.[18-20], the overall average goes up when the number of packets goes up. For 2.6.0-test6, it stays constant.
Chris
-- Chris Friesen | MailStop: 043/33/F10 Nortel Networks | work: (613) 765-0557 3500 Carling Avenue | fax: (613) 765-2986 Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com
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