[coyotos-dev] Need for revised invocation

Jonathan S. Shapiro shap at eros-os.org
Sun Feb 5 23:01:57 EST 2006


On Sun, 2006-02-05 at 17:21 -0800, Charles Landau wrote:

> >   1. TCP slow-timeout.
> >   2. The remaining 15% of bandwidth in the gigabit ethernet case.
> 
> There isn't enough information there for me to comment. Perhaps you 
> have time now to elaborate?

The TCP slow-timeout is a shared-memory variable that is used within the
TCP implementation to decide when to check for stalled packets on
queued. At various points the mainline code checks to see if this
variable has been set to 1. Setting a single word to 1 should not
require an entire process to accomplish.

The gigabit ethernet case could possible be solved with a kernel service
as you have suggested, but the expense of this is non-trivial. I'm not
entirely convinced that this design eliminates the extra context
switches or the scheduling issues that I raised in my earlier discussion
of the ethernet case, and it *definitely* does not provide any means to
effectively amortize I/O latencies.


shap



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