>>>> Hi Maxime, >>>> >>>> I did a little more macswap test and found out more stuff here: >>> Thanks for doing more tests. >>> >>>> >>>> 1. I did loopback test on another HSW machine with the same H/W, >>>> and indirect_desc on and off seems have close perf >>>> >>>> 2. So I checked the gcc version: >>>> >>>> * Previous: gcc version 6.2.1 20160916 (Fedora 24) >>>> >>>> * New: gcc version 5.4.0 20160609 (Ubuntu 16.04.1 LTS) >>> >>> On my side, I tested with RHEL7.3: >>> - gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11) >>> >>> It certainly contains some backports from newer GCC versions. >>> >>>> >>>> On previous one indirect_desc has 20% drop >>>> >>>> 3. Then I compiled binary on Ubuntu and scp to Fedora, and as >>>> expected I got the same perf as on Ubuntu, and the perf gap >>>> disappeared, so gcc is definitely one factor here >>>> >>>> 4. Then I use the Ubuntu binary on Fedora for PVP test, then the >>>> perf gap comes back again and the same with the Fedora binary >>>> results, indirect_desc causes about 20% drop >>> >>> Let me know if I understand correctly: > > Yes, and it's hard to breakdown further at this time. > > Also we may need to check whether it's caused by certain NIC > model. Unfortunately I don't have the right setup right now. > >>> Loopback test with macswap: >>> - gcc version 6.2.1 : 20% perf drop >>> - gcc version 5.4.0 : No drop >>> >>> PVP test with macswap: >>> - gcc version 6.2.1 : 20% perf drop >>> - gcc version 5.4.0 : 20% perf drop >> >> I forgot to ask, did you recompile only host, or both host and guest >> testmpd's in your test?
> Both. I recompiled testpmd on a Fedora 24 machine using GCC6: gcc (GCC) 6.1.1 20160621 (Red Hat 6.1.1-3) Testing loopback with macswap on my Haswell RHEL7.3 machine gives me the following results: - indirect on: 7.75Mpps - indirect off: 7.35Mpps Surprisingly, I get better results with indirect on my setup (I reproduced the tests multiple times). Do you have a document explaining the tuning/config you apply to both the host and the guest (isolation, HT, hugepage size, ...) in your setup? Regards, Maxime
