Re: [RFA/commit] Add support for DEC threads on alpha-osf

Joel Brobecker
2008-10-07T15:02:33Z

Thanks for the quick feedback!

> Hmmm, procfs.c. It looks weird that LWP 3 and the main process are
> the same thing. If they are the same, and I haven't messed something up,
> you should only see one of them. IIRC, I don't get that on solaris.

How does it work (to determine whether the process and the LWP are
the same)? I could probably take a look. Not sure whether I could
help much, though.

> ... this is an M:N configuration? It looks like it, because threads
> 2,3,4 were added before the lwps 5,6,7, and the threads 2,3 show a
> different frame from lwps 5,6.

I am strongly suspecting that it is indeed an M:N configuration,
but I don't know that for sure. The LWPs look like kernel threads
(the pthreaddebug API mentions their existence).

> Or, are all user threads scheduled on the main process/lwp ? Then what
> the heck is thread 5 blocked on ? :-)

Very simple: I don't know :). The threads library is a black box
to me. Any other question?

> Anyway, these are all dumb question that came to mind, because
> I miss a description of DEC's thread model at the top of
> dec-thread.c. Something akin to sol-thread.c, but needn't
> be so extensive. :-)

Yes, I miss this description too :). I searched all the headers
as well as the web, and didn't find anything useful. So, my
conclusion at this point is that we can only go with the suspicion
that it is indeed and M:N model. There might be a bug (process
thread should not show up if identical to one of the LWPs),
but this is separate from my patch. I don't mind having a quick
look if it's not too time-consuming. What do you think?

--
Joel