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USB CDC ACM has low throughput #14288

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masz-nordic opened this issue Mar 12, 2019 · 4 comments
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USB CDC ACM has low throughput #14288

masz-nordic opened this issue Mar 12, 2019 · 4 comments
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@finikorg @pawelzadrozniak
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area: USB Universal Serial Bus Enhancement Changes/Updates/Additions to existing features

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@masz-nordic
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Is your enhancement proposal related to a problem? Please describe.
To reproduce:

  • Disable loopback in cdc_acm sample by commenting out write_data(dev, data_buf, *bytes_read);.
  • Build and flash cdc_acm sample.
  • pv --force -B 256 sample.txt 2>&1 > /dev/ttyACM1 where sample.txt is a big file.
  • Observe the throughput.

Results:

  • cdc_acm without loopback: 51 KB/s
  • as above, with disabled logs: 96 KB/s

Describe the solution you'd like
CDC ACM should reach throughput of at least 400 kB/s.

Additional context
Board: nrf52840_pca10056
OS: Ubuntu 16.04, 4.13.0
Zephyr: c78c5e6
@masz-nordic masz-nordic added Enhancement Changes/Updates/Additions to existing features area: USB Universal Serial Bus labels Mar 12, 2019
@masz-nordic
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The bottleneck seems to be located in this read.

@finikorg
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The bottleneck seems to be located in this read.

Since we do not have it for other classes, we can remove it. This should be handled in the dc code.

@carlescufi
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@finikorg can you send a PR to remove that read?

@finikorg
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@finikorg can you send a PR to remove that read?

PR #14677

@finikorg finikorg mentioned this issue Mar 20, 2019
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finikorg added a commit to finikorg/zephyr that referenced this issue Mar 22, 2019
@finikorg
usb: cdc_acm: Use ringbuf for RX path
da6c374 
Use ringbuf library for handling RX CDC ACM path. Remove old code
artifacts handling specific hardware.

Fixes zephyrproject-rtos#14288

Signed-off-by: Andrei Emeltchenko <[email protected]>
carlescufi pushed a commit that referenced this issue Mar 25, 2019
@finikorg @carlescufi
usb: cdc_acm: Use ringbuf for RX path
cd95560 
Use ringbuf library for handling RX CDC ACM path. Remove old code
artifacts handling specific hardware.

Fixes #14288

Signed-off-by: Andrei Emeltchenko <[email protected]>
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@finikorg @carlescufi @pawelzadrozniak @masz-nordic