https://bugs.dpdk.org/show_bug.cgi?id=188
Bug ID: 188
Summary: significant multi-core performance degradation with
SR-IOV/macswap in some cases
Product: DPDK
Version: 19.02
Hardware: x86
OS: Linux
Status: CONFIRMED
Severity: critical
Priority: Normal
Component: testpmd
Assignee: dev@dpdk.org
Reporter: alia...@mellanox.com
Target Milestone: ---
Hi,
I'm seeing a performance degradation with testpmd running with multiple cores.
I saw the issue with ConnectX-3, ConnectX-4 Lx, and ConnectX-5.
### For ConnectX-3:
- With 2 Cores, I see a degradation from 19.2 mpps to 13.5 mpps.
testpmd command:
`MLX4_INLINE_RECV_SIZE=64 ./build/app/test-pmd/testpmd -c 0x7 -n 4 -w
0002:00:02.0 --vdev=net_vdev_netvsc,ignore=1 --socket-mem=2048 --
--port-numa-config=0,0 --socket-num=0 --burst=64 --txd=256 --rxd=256
--mbcache=512 --rxq=2 --txq=2 --nb-cores=2 -i -a --forward-mode=macswap`
- With 4 Cores, I see a degradation from 19.2 mpps - 13.9 mpps.
testpmd command:
`MLX4_INLINE_RECV_SIZE=64 ./build/app/test-pmd/testpmd -c 0x1f -n 4 -w
0002:00:02.0 --vdev=net_vdev_netvsc,ignore=1 --socket-mem=2048 --
--port-numa-config=0,0 --socket-num=0 --burst=64 --txd=256 --rxd=256
--mbcache=512 --rxq=2 --txq=2 --nb-cores=4 -i -a --forward-mode=macswap`
### For ConnectX-4 Lx:
- With 2 Cores, I see a degradation from 32.9 mpps to 26.8 mpps.
testpmd command:
`./build/app/test-pmd/testpmd -c 0x7 -n 4 -w 0003:00:02.0
--vdev="net_vdev_netvsc,ignore=1" -- --burst=64 --txd=1024 --rxd=256
--mbcache=512 --rxq=2 --txq=2 --nb-cores=2 --rss-udp --port-topology=chained
--forward-mode=macswap -i -a`
- With 4 Cores, I see a degradation from 34.8 mpps to 19 mpps.
testpmd command:
`./build/app/test-pmd/testpmd -c 0x1f -n 4 -w 0003:00:02.0
--vdev="net_vdev_netvsc,ignore=1" -- --burst=64 --txd=8192 --rxd=256
--mbcache=512 --rxq=4 --txq=4 --nb-cores=4 --rss-udp --port-topology=chained
--forward-mode=macswap -i -a`
Server specs:
OS: Ubuntu 16.04.2 LTS
Kernel: 4.15.0-rc3
I'm using IXIA as a traffic generator, and to get the forwarding performance.
DPDK version: master:a89fbda
The cause of the degradation is the patch:
```
commit 62b52877adbe8d3ad19615b0827e7725e51feadc
Author: Qi Zhang <qi.z.zh...@intel.com>
Date: Sun Dec 16 08:58:35 2018 +0800
app/testpmd: batch MAC swap for performance on x86
Do four packets macswap in same loop iterate to squeeze more
CPU cycles.
Signed-off-by: Qi Zhang <qi.z.zh...@intel.com>
Reviewed-by: Ferruh Yigit <ferruh.yi...@intel.com>
Acked-by: Bernard Iremonger <bernard.iremon...@intel.com>
```
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