Hi,
On Tue, Feb 13, 2024 at 01:04:17PM +0100, Marc Kleine-Budde wrote:
> On 13.02.2024 06:45:04, Dave Taht wrote:
> > while I am delighted to see this, what is the observed benefit?
>
> Let's add Markus (the author of this patch) and the linux-can Mailing
> list on Cc. I haven't implemented this feature, but Markus has.
>
> IIRC BQL is mandatory for xmit_more(). And xmit_more() is used to batch
> more then one transfer from the host to the CAN controller. This brings
> a performance improvement on for tcan4x5x, which is connected via SPI.
> And SPI is a quite slow bus with lots of overhead (at least on Linux).
Yes, exactly, it is in preparation of the next patch in this series
can: m_can: Implement transmit submission coalescing
In this patch I am using netdev_xmit_more() to see if we can batch a bit
another transmit before submitting all transmits. For tcan4x5x this
reduces the number of SPI transfers as the final submission of a
transmit is a separate SPI register write.
Best,
Markus
