Re: proc fs and shared pids

Theodore Y. Ts'o (tytso@mit.edu)
Wed, 7 Aug 1996 20:45:04 -0400


From: peter@ifm.liu.se (Peter Eriksson)
Date: 7 Aug 1996 15:12:21 GMT

I see one problem with this 16bit "thread-ID" idea - it's not
impossible one would need more than 65536 concurrent threads,=20
and what would one do then? Let's try to avoid stepping into the
640KB-is-more-than-anyone-would-ever-need trap again...

I'm sure you can construct a proof-by-counter example that's it's
possible that a program could actually try to create 65536 concurrent
threads. I'd really like to see, however, an example of when you'd
actually really want to *use* 65336 threads. People have raised the
example of transputers where you have more than 64k computers ---
however, in these cases, you *won't* be sharing memory, so you wouldn't
be using separate threads anyway. (The thought of trying to do memory
cache coherency checking across 64k processor makes me shiver....)

I can think of bad design decisions that result in needing more than 64k
threads; what I'd like to see is a legitimate example which doesn't
involve a bad design decision. :-)

- Ted