[TUHS] Code bloat (was: How Unix brings people together, or it's a small...)

Noel Chiappa jnc at mercury.lcs.mit.edu
Fri Feb 10 00:31:06 AEST 2017


    > From: Paul Ruizendaal

    > The best one seems to have been the 3Com stack, which puts IP in the
    > kernel and TCP in a daemon.

I've gotta get the MIT V6 one online.

Incoming demux is in the kernel; all of the TCP, and everything else, is in
processes along with the application - one process per application instance.
It sounds like it might be clunky, but it's not: there are a couple of
different TCP's (a small, low performance one for things like User TELNET,
timer servers, yadda-yadda; a bigger, higher-performance one for things like
FTP), and the application just calls them as subroutine libraries
(effectively). Since there's no IPC overhead, the performance is pretty good.

Unfortumately, a lot of the stuff never migrated from personal directories to
the system folder, so I have to go curate out the personal files (or, more
likely, move them all to a system folder) before I can release it all.


    > Perhaps economizing on fragmentation and and window management is
    > better.

Fragmentation, perhaps - but good window management is a must.

    > I wonder if just putting the code for this state in the kernel and
    > handling only the state changes and other states in a daemon is perhaps
    > the best split on constrained hardware.

I don't think that's a good idea; cutting the TCP in two parts, which have to
communicate over an interface is going to be _really_ ugly: do you have one
copy of the connection state data (in which case one them has to go through an
interface to get to it), or two (synchronization issues). If you want a small
kernel footprint, take the MIT approach.

       Noel


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