On 2017-04-10 2:50 PM, Jarod Wilson wrote:
On 2017-04-08 7:33 PM, Jarod Wilson wrote:
I'm digging into some bug reports covering performance issues with
balance-rr, and discovered something even worse than the reporter. My
test setup has a pair of NICs, one e1000e, one e1000 (but dual e1000e
seems the same). When I do a test run in LNST with bonding mode
balance-rr and either miimon or arpmon, the throughput of the
UDP_STREAM netperf test is absolutely horrible:
TCP: 941.19 +-0.88 mbits/sec
UDP: 45.42 +-4.59 mbits/sec
I figured I'd try LNST's packet capture mode, so exact same test, add
the -p flag and I get:
TCP: 941.21 +-0.82 mbits/sec
UDP: 961.54 +-0.01 mbits/sec
Uh. What? So yeah. I can't capture the traffic in the bad case, but I
guess that gives some potential insight into what's not happening
correctly in either the bonding driver or the NIC drivers... More
digging forthcoming, but first I have a flooded basement to deal with,
so if in the interim, anyone has some insight, I'd be happy to hear
it. :)
Okay, ignore the bit about bonding, I should have eliminated the bond
from the picture entirely. I think the traffic simply ended up on the
e1000 on the non-capture test and on the e1000e for the capture test, as
those numbers match perfectly with straight NIC to NIC testing, no bond
involved. That said, really odd that the e1000 is so severely crippled
for UDP, while TCP is still respectable. Not sure if I have a flaky NIC
or what...
For reference, e1000 to e1000e netperf:
TCP_STREAM: Measured rate was 849.95 +-1.32 mbits/sec
UDP_STREAM: Measured rate was 44.73 +-5.73 mbits/sec
The rabbit hole went even deeper. The actual problem was with the ITE
8893 PCIe bridge in the host not properly exposing capabilities, which
required a pci quirk identical to that of the ITE 8892 to work around.
With that in place, throughput on this venerable old e1000 goes back up
to a reasonable 900 mbits/sec, give or take.
--
Jarod Wilson
ja...@redhat.com
