user-space threads

[Boehm, Hans]

> Are you guys aware of the NGPT project at IBM? It's an M:N threading
> library based on Ralf's pth project. It has many of the advantages of
> user space threads (ie: an abstraction over kernel threads) without
> requriing specific library support (it provides a modified pthreads
> library).
> 
I'm very aware of it.  The issue of porting the GC to it has come up, but AFAIK it hasn't happened.  Based on what I've seen, I prefer the NPTL approach.  (Details on request.)  More importantly, the glibc maintainer, Ulrich Drepper, is one of the people behind NPTL, a project that was apparently started in response to a push for NGPT support in glibc.

NPTL is a refinement of the 1:1 linuxthreads model, with better kernel support, and more attention to performance for thread creation, synchronization and per-thread data access.  NGPT implements basically the Solaris M:N model.  My understanding is that Sun is currently backing off that model, and they have not been using it for reported SPECjbb runs for quite a while.  There are some VERY limited performance comparisons for linuxthreads, NPT(L), and NGPT at https://listman.redhat.com/pipermail/phil-list/2002-September/000009.html .

Hans