On 4/1/24 6:39 PM, Hari Nagalla wrote:
On 3/25/24 12:20, Andrew Davis wrote:
The kernel FIFO queue has a couple issues. The biggest issue is that
it causes extra latency in a path that can be used in real-time tasks,
such as communication with real-time remote processors.
The whole FIFO idea itself looks to be a leftover from before the
unified mailbox framework. The current mailbox framework expects
mbox_chan_received_data() to be called with data immediately as it
arrives. Remove the FIFO and pass the messages to the mailbox
framework directly.
Yes, this would definitely speed up the message receive path. With RT linux, the irq runs in thread context, so that is Ok. But with non-RT the whole receive path runs in interrupt context. So, i think it would be appropriate to use a threaded_irq()?
I was thinking the same at first, but seems some mailbox drivers use threaded, others
use non-threaded context. Since all we do in the IRQ context anymore is call
mbox_chan_received_data(), which is supposed to be IRQ safe, then it should be fine
either way. So for now I just kept this using the regular IRQ context as before.
If that does turn out to be an issue then let's switch to threaded.
Andrew
