Re: [patch] bug fix & TCP networking performance improvements

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

dyoung%pobox.com@localhost said:
> When a protocol-drain routines called in an interrupt context sleeps,
> the system deadlocks.

What do you mean exactly here? Sleeping in an interrupt context is
a hard error, not just a deadlock. Or is this about a deadlock
at a more functional level, where some memory might need to be
allocated short-term to be able to free a bigger chunk?
I don't mind the move from the "drain" entry to "fasttimo"
(ahthough it could have performance implications in cases
where the 1000 lingering connections are not needed) but
want to understand the issues. I think to get to better
MP concurrency it makes sense to get the drain/fast/slowtimo
entries out of KERNEL_LOCK, protocol by protocol which would
need some flag(s) in the protosw.

I can't comment on the VTW implementation itself, just some
comments on mostly formal things:

> lower MSLs by default: 2 seconds for loopback
This looks short. In particular with filesystem pressure my boxes
are often unresponsive for significantly longer. There is no
justification for the big difference to
> 10 seconds for local

Some "#ifdef INET6" and so seem to be missing to reduce bloat.

There is some change about permissions for raw sockets which
is not explained.

The netstat change is not documentsd.

And tlas as "vtw" are not in common use so I'd avoid that for
visible things like filenames.

best regards
Matthias



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