Re: question on incoming packets and scheduler

["Andrew R. Reiter" <arr@watson.org>]

On Wed, 15 Oct 2003, Chris Friesen wrote:

: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.

I would be interested in seeing the test be run with epoll too :)  I
ealize .18 doesn't support this, but how about it for .20?  If not,
perhaps you could shoot over the code and I could test?

Cheers,
Andrew

--
Andrew R. Reiter
arr@watson.org
arr@FreeBSD.org