Data transfer mechanisms

Lluís Vilanova vilanova at
Sun Aug 11 19:10:29 CEST 2013


I'd like to compare the performance of two different synchronous data transfer

* Copies
* Page maps / unmaps

For the second one, it looks like I can use the streammap example
(pkg/examples/libs/l4re/streammap), although I'm lacking a mechanism to unmap
the page before returning control to the client. It would also be nice to be
able to pass the server a read-only region.

For the first one, I've only found the use of multiple send/recv operations
through the limited amount of data available on the message registers. There is
a "Gen_string" class in the "ipc_stream" header, which looks like it could
support offline string transfers, but it's disabled at compile time and I could
not find the actual code in fiasco that handles these transfers.


 "And it's much the same thing with knowledge, for whenever you learn
 something new, the whole world becomes that much richer."
 -- The Princess of Pure Reason, as told by Norton Juster in The Phantom

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