Michael Iatrou wrote:
Hi,
I did several benchmarks using Intel e1000 NIC and it seems there is a
network throughput problem for MTU > 12000 (e1000 supports up to 16110
MTU).
Configuration:
Two identical PCs, connected back to back, Intel Xeon 2.8GHz (SMP/SMT
disabled), 512MB RAM, e1000 (82546EB)
Linux 2.6.11.7
netperf 2.3pl1
What settings, if any, did you use for -s, -S and in particular -m in netperf?
I seem to recall that some of the stack defaults for SO_SNDBUF (IIRC) would
result in netperf sending 16KB at a time into the connection - once you sent the
MTU above 16K you may have started running into issues with Nagle and delayed
ACK? You could try some tests adding a test-specific -D to disable Nagle, or -C
to set TCP_CORK, or use -m to set the send size to say, 32KB.
It might be good to add CPU utilization figures - for 2.3pl1 that means editing
the makefile to add a -DUSE_PROC_STAT and recompiling. Or you can grab netperf
2.4.0-rc3 from:
ftp://ftp.cup.hp.com/dist/networking/benchmarks/netperf/experimental/
if you cannot find it elsewhere, and that will (try to) compile-in the right CPU
utilization mechanism automagically.
rick jones
|