[Intel-wired-lan] i40e performance regression after 1.3.9 ?

Ray Bellis ray at isc.org
Tue Nov 8 10:30:30 UTC 2016


On 07/11/2016 20:44, Alexander Duyck wrote:

> The adaptive Rx and Tx being disabled is the important part.  If you
> didn't do that then changing the other values really had no effect.

I've just confirmed that turning off adaptive Rx and Tx on the "server"
side has the desired effect, bringing my packet rate back up to 1.3+ Mpps.

I'm getting odd effects when I try this on the "client" side though
(with the dnsperf program which generates packets and then waits for the
response)

With the 1.3.9 driver, I get a pretty consistent packet rate:

1478599801.555815: 1346798.548250
1478599802.556818: 1345090.873854
1478599803.557820: 1348886.415811
1478599804.558826: 1347842.070877
1478599805.559823: 1346257.780992
1478599806.560821: 1347437.257617
1478599807.561818: 1346674.365657
1478599808.562824: 1351776.113230
1478599809.563818: 1347379.704574

I then unload the driver and install the new one:

# ifdown enp5s0f1
Device 'enp5s0f1' successfully disconnected.
# rmmod i40e
# insmod ./i40e-1.3.38-4.3.5-300.fc23.ko
# ifup enp5s0f1
# ethtool -C enp5s0f1 adaptive-rx off adaptive-tx off

and re-running the test the packet rates are all over the place, and
almost seem to be trending downwards over time:

1478599891.282086: 1064831.565393
1478599892.282814: 1013365.270083
1478599893.283820: 958262.987435
1478599894.284814: 960207.553692
1478599895.285817: 947161.996517
1478599896.286852: 964507.734495
1478599897.287818: 991703.014888
1478599898.288815: 1010553.478182
1478599899.289822: 963053.205422
1478599900.290860: 933701.817513
1478599901.291816: 988006.465819
1478599902.292821: 957132.082257
1478599903.293822: 1017923.059018
1478599904.294820: 974373.575172
1478599905.295816: 947963.828027
1478599906.296817: 943062.993943
1478599907.297851: 885024.884270
1478599908.298818: 868948.726581
1478599909.299814: 945017.762309
1478599910.300846: 954253.210687
1478599911.301817: 936898.271778
1478599912.302818: 885917.196886

Even more bizarrely, the first time I ran this test it actually gave me
the expected 1.35 Mpps for the first ten seconds or so before
(gradually) dropping down to 1 Mpps or less.

More experimentation required - I'll do so with some reboots rather that
rmmod / insmod.

Ray







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