On 18 Nov 2021, at 08:24, Gerwin Klein firstname.lastname@example.org wrote:
The page reports the 0-length numbers. The idea is that IPC should fit into registers, the 10 case is the one that make it spill into memory deliberately. That number is good to know for development, but should not be the main performance characteristic.
Note that whether data is transferred solely in registers or using a memory buffer does not make a big difference on contemporary hardware. However, our present implementation reverts to the slow path as soon as the message size overflows the physical message registers, which will make the PIC much slower.
This is something that could be fixed by widening the fastpath conditions without much complications. However, we haven’t yet come across an important use case where this matters, so there isn’t much motivation for investing time in it.