samples: net: zperf: Optimize configuration for better performance #75281
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samples/net/zperf/prj.conf
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| CONFIG_NET_PKT_RX_COUNT=50 | ||
| CONFIG_NET_PKT_TX_COUNT=50 | ||
| CONFIG_NET_BUF_RX_COUNT=300 | ||
| CONFIG_NET_BUF_TX_COUNT=300 |
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Tried this with NXP imxrt1050-evkb board, and the Zephyr download throughput drops to 79.06 Mbps with this.
With slightly lower values
CONFIG_NET_PKT_RX_COUNT=40
CONFIG_NET_PKT_TX_COUNT=40
CONFIG_NET_BUF_RX_COUNT=160
CONFIG_NET_BUF_TX_COUNT=160
the throughput rises to 94.4 Mbits/sec
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I'll check this with my STM, I recall I couldn't reach maximum TCP download throughput with lower buffer count.
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Ok, both TCP TX and RX degraded a bit with those configs:
TCP TX RX
74.19 Mbps 85.51 Mbps
But they're still not bad so I guess it's fine?
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It is weird how the numbers change when having more buffers in NXP but with STM the results are more in line what to expect.
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@dleach02 any idea why increasing network buffers for NXP boards gives worse results than having a lower net buf count? We could discuss the zperf issues next week in network forum meeting. |
samples/net/zperf/README.rst
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| .. code-block:: cfg | ||
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| CONFIG_NET_PKT_RX_COUNT=50 |
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Ensure that these values match the prj.conf
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Interesting things are going on lately. What I do not understand is why the UDP TX performance of Zephyr is so bad in comparison. Also in the report that NXP released lately this was very clear. |
Increase the number of network packets and buffers for better TCP
performance in the sample out-of-the-box.
Decrease the network buffer data size for better buffer management in
the sample (less buffer space wasted for L2 header). The only drawback
of this is reduced TCP TX performance, but less than 2 Mbps in my case.
Finally, enable speed optimizations for another small performance boost.
As the RAM requirements of the sample now increase considerably in the
default configuration, add a note in the readme file about it, and how
to make it fit into smaller boards.
Tested on nucleo_h723zg:
Before (current defaults):
UDP TX RX
76.47 Mbps 93.48 Mbps
TCP TX RX
76.18 Mbps 67.75 Mbps
After (new defaults):
UDP TX RX
76.08 Mbps 93.62 Mbps
TCP TX RX
74.19 Mbps 85.51 Mbps
Signed-off-by: Robert Lubos <[email protected]>
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I just looked at the UDP TX path and recently had a mail conversation with @dleach02 on the performance. Is the fact that the transmitted packets always go through a separate thread a significant contributor to the lower (UDP) TX performance? A reasonable simple way to test is would be to see if playing with CONFIG_NET_TC_SKIP_FOR_HIGH_PRIO has a significant impact. Line 356 in 2e956c2 If this is of significant influence we might need to look if this can be implemented in a different way. |
Actually, when I was testing the impact of a separate TX thread in the past, I've observed quite a contrary, see the table in #23302 (comment). But that was because the driver I've used blocked the thread for the transmission (hence offloading it to a separate thread allowed the net stack to already prepare the next packet instead of waiting). |
In default settings, there is no separate TX thread in the system. If userspace is enabled, then there needs to be one TX thread. Line 200 in 1ed04e7 |
Increase the number of network packets and buffers for better TCP performance in the sample out-of-the-box.
Decrease the network buffer data size for better buffer management in the sample (less buffer space wasted for L2 header). The only drawback of this is reduced TCP TX performance, but less than 2 Mbps in my case.
Finally, enable speed optimizations for another small performance boost.
As the RAM requirements of the sample now increase considerably in the default configuration, add a note in the readme file about it, and how to make it fit into smaller boards.
Tested on nucleo_h723zg: