Re: ld.so, threads

Gavin Nicol wrote:
>
> Andy, what is the general technique used fir the shared libraries? We
> don't need specifics, but I for one would like to know whether it's
> jump tables, PIC or something else.

I'd be interested in this one as judging from the debates raging in the
Linux world this could have an interesting effect on performance.

> Also, has anyone thought of writing some wrappers for VSTa threads to
> make them POSIX threads compatible? Is this worth it? I think that as
> everyone gets used to multithreaded programming, more and more of the
> servers will become multithreaded; MADO certainly will be. We also
> need more threadsafe library code; things like lists, queues, trees,
> semaphores...

I didn't think the POSIX spec had stabilised yet (or am I just
misinformed?). The biggest problem I've seen with implementing thread safe
libraries (eg libc) is that we're using kernel threads. We need a mechanism
that would allow any per-thread data used in the libraries to be changed
during a thread context-switch. This must have been solved before, but I
don't know how (the only solution I've thought of so far wasn't exactly
elegant).

I think that for any sort of async I/O multithreaded must be the way to go -
the biggest argument against this seems to be debug support (there seem to
be some good flame wars raging on this in some of the O/S newsgroups).
Having written MS-Windows apps in the past though I'm no fan of purely
event-driven apps.

> Finally, now that shared libraries look like they'll be coming along,
> I think we should probably start moving over toward unicode support. I
> have the beginnings of a wide string library done, but I stopped work
> on it partly because of the size of the table needed for things like
> ispunct() et al. Once I get a few hours, I'll dust off the code, and
> finish it off. I'll also hack on doprnt. I want MADO and bitblt to be
> able to handle Unicode...

Unicode would be really good generally - would we need to see about
supporting multibyte characters in gcc? (I seem to remember reading that
the Plan 9 folks had done that). As for bitblt, I don't doubt for a second
that we we'll have multibyte support :-) :-)

                Regards,
                 Dave
Received on Sun Sep 25 15:39:24 1994