ixl 40G bad performance?

[Eggert, Lars]

Hi,

in order to eliminate network or hardware weirdness, I've rerun the test with Linux 4.3rc6, where I get 13.1 Gbits/sec throughput and 52 usec flood ping latency. Not great either, but in line with earlier experiments with Mellanox NICs and an untuned Linux system.

On 2015-10-19, at 17:11, Luigi Rizzo <rizzo at iet.unipi.it> wrote:
> I suspect it might not touch the c states, but better check. The safest is
> disable them in the bios.

I'll try that.

>> hw.ixl.dynamic_tx_itr: 0
>> hw.ixl.dynamic_rx_itr: 0
>> 
>> 
> There must be some other control for the actual (fixed, not dynamic)
> moderation.

The only other sysctls in ixl(4) that look relevant are:

     hw.ixl.rx_itr
             The RX interrupt rate value, set to 8K by default.

     hw.ixl.tx_itr
             The TX interrupt rate value, set to 4K by default.

I'll play with those.

>> Also no change with "hw.ixl.ringsz=256" in loader.conf.
> 
> Any better success with 2048 slots?
> 3.5 gbit  is what I used to see on the ixgbe with tso disabled, probably
> hitting a CPU bound.

Will try.

Thanks!

Lars
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