When doing PVP (Physical to Virtual to Physical) testing, we measure a performance degradation when testpmd in guest is launched without the --legacy-mem parameter. P to V and V to P forwarding is done using OVS-DPDK on host side. Without the --legacy-mem option, we get ~23% of line rate at 10G. With the --legacy-mem option, we get ~29% of line rate at 10G. 1G hugepages are used both in host and guest. Testpmd command line used in guest: testpmd -c 7 -n 4 --socket-mem 2048 0 -w 0000:00:02.0 --legacy-mem -- --burst 64 -i --rxq=2 --txq=2 --rxd=4096 --txd=1024 --coremask=6 --auto-start --port-topology=chained --forward-mode=macswap testpmd -c 7 -n 4 --socket-mem 2048 0 -w 0000:00:02.0 -- --burst 64 -i --rxq=2 --txq=2 --rxd=4096 --txd=1024 --coremask=6 --auto-start --port-topology=chained --forward-mode=macswap
Note that the issue is seen starting v18.05, but is reproduced with DPDK v18.11 LTS.
Does it by any chance depend on IOVA contiguousness? And what is the IOVA mode when running these?
Maxime, IS this still an issue? If yes, can you respond to Anatoly's questions? Thanks