Re: emulating no-senders notifications in L4?

[Roland McGrath]

> nisse@lysator.liu.se (Niels Möller) writes:
> 
> > I believe this class of "simple" rpc:s is what matters for
> > performance.
> 
> I'm not so sure of that.  One critical cases are dir_lookup (which
> makes transfers of ports both ways).  But it's hard to say for sure
> without some instrumentation.

It's clear that the overhead of io_read and io_write is more critical
than that of dir_lookup, which always entails some overhead for
transferring ports.  I think that's the point Niels was making.