Smallrye, through the usage of OnOverflow annotation, allows configure the backpressure strategy of every Emitter. See this post for more info on that topic .
Right now, the only configurable setting is the default buffer size (default strategy is buffer) for all channels, though the usage of property

 mp.messaging.emitter.default-buffer-size 

It would be nice to have the possibility to change the default strategy and buffer size per each channel. The proposal is to add properties of the following form to Kogito:

kogito.addon.messaging.emitter.<channel_name>.overflow-strategy=BUFFER|NONE|UNBOUNDED|FAIL|DROP
kogito.addon.messaging.emitter.<channel_name>.buffer-size=size of the buffer

We should allow changing the strategy globally for all channels, with a property

kogito.addon.messaging.emitter.overflow-strategy=BUFFER|NORE|UNBOUNDED|FAIL|DROP