Hey there, fn dev here. Cool to hear about folks testing the graal images! We have done some experimental work and made some discoveries in the container cold start time dept. which we've documented https://blogs.oracle.com/developers/building-a-container-run... (see: Fast Container Startup).
The main things are optimizations around pre-allocating network namespaces, we've built some experimental code to skirt around this https://github.com/fnproject/fn/blob/master/api/agent/driver... (which can be configured & tested) and we're testing approaches like this to attempt to get start times down to as low as we can. <100ms still seems like a lofty goal at this point, but this is becoming a pain point for various FaaS platforms that are container based and some optimization work should come out of all this. A few layers up, it's a little easier to speed things when throughput increases for a given function, but devs do seem to want the 0->1 case to be almost as fast as the 'hot' case so we FaaS people need to answer this better in general, it isn't something we want users to have to think about!
The main things are optimizations around pre-allocating network namespaces, we've built some experimental code to skirt around this https://github.com/fnproject/fn/blob/master/api/agent/driver... (which can be configured & tested) and we're testing approaches like this to attempt to get start times down to as low as we can. <100ms still seems like a lofty goal at this point, but this is becoming a pain point for various FaaS platforms that are container based and some optimization work should come out of all this. A few layers up, it's a little easier to speed things when throughput increases for a given function, but devs do seem to want the 0->1 case to be almost as fast as the 'hot' case so we FaaS people need to answer this better in general, it isn't something we want users to have to think about!