Call for performance evaluation: net.isr.direct (fwd)

[Garrett Wollman]

<<On Sun, 16 Oct 2005 14:06:32 +1000 (EST), Bruce Evans <bde at zeta.org.au> said:

> Probably the problem is largest for latency, especially in benchmarks.
> Latency benchmarks probably have to start cold, so they have no chance
> of queue lengths > 1, so there must be a context switch per packet and
> may be 2.

It has frequently been proposed that one of the deficiencies of the
sockets model is that too much work must take place in interrupt
context.  Several alternatives have been suggested, including
user-mode protocol processing (e.g., Exokernel) and event-driven
receive (can't think of an example here from the literature).  In an
alternate universe with truly pervasive threading, one might require
an application to "donate" a thread to protocol processing --
effectively combining the two approaches I mentioned -- which would be
the way to "win" such latency benchmarks.  (The application donating
the processing power is then also able to donate its memory.)

-GAWollman