libkse -> libpthread

[Daniel Eischen]

On Mon, 21 Apr 2003, Terry Lambert wrote:

> Jeff Roberson wrote:
> > On Mon, 21 Apr 2003, Daniel Eischen wrote:
> > > Since libkse seems to be generally useful, anyone mind if I
> > > go back to installing it as libpthread?
> > 
> > There is some question over whether kse or thr will be the default
> > threading implementation for 5.1.  I think this should be discussed before
> > we decide on what lib uses libpthread.
> 
> Isn't libthr really just libkse with N = M?

Yes, I wasn't going to bring that up, though.

> These should behave exactly the same, right?  It should even be
> possible to drop the UTS out of the picture for everything but
> signal handling, I think (i.e. it would never get upcalled) in
> the 1:1 case, if this were done?

Libpthread can be made to behave the same as libthr just
by forcing every thread to be scope system.  Currently,
the implementation for scope system threads does have
a small amount of overhead in that they still get upcalls
after the thread blocks in the kernel (in this case
the KSE just reenters the kernel with kse_release()
and waits for the thread to become unblocked).  These
KSEs also require a small stack separate from the
thread's stack.  The code is in place (in the UTS) to
not require a separate stack and not get any upcalls
for these threads, but we just need a bit more
kernel work to optimize this overhead away.

I do have scope system threads running in a simple
test program.

-- 
Dan Eischen