On 19.05.2022 17:52:36, Michael Anochin wrote:
> my application continuously sends 64 bytes CANFD packets with 1MBit/s at the
> 10ms interval. I use tcan4450 on the RPI4 with 5.10.103 Kernel and raspbian.
> No other significant processes load the CPU.
> 
> When I monitor the traffic with a PCAN adapter on a Windows PC, I notice
> that the packets sometimes arrive with a delay of 5-9ms. But the next
> following packet arrive faster as 10ms. My desired interval of 10ms is kept
> at the jitter of +/- 9ms.
> 
> Running the App on only one CPU core using tasksel improve the jitter
> somewhat.
> 
> Am I the only one who observes such large jitter or is the m_can
> implementation at Perepherie (spi) not so fast from the throughput and is
> completely normal.
> 
> Maybe I should switch to 5.17 kernel? On 5.17 there are bulk read/write
> function for spi regmap.

The tcan4x5x driver is not really optimized. Don't expect great
performance with it. At least the newer kernel have some kind of
optimization. There are a lot of further optimization opportunities
which are already implemented in the mcp251xfd driver.

regards,
Marc

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