Re: RasterMan on linux and threads

Brian Pomerantz (bapper@piratehaven.org)
Fri, 17 Dec 1999 16:15:37 -0800

On Fri, Dec 17, 1999 at 11:23:48PM -0500, Stephen Frost wrote:
> >
> > hmm - when did that change ? i thought that was the case and was baked
> > up on hat asumtion by someone else a few weeks ago (primarily the
> > reason being to make sure the threads share caches for speed reasons
> > and to make sure cache concurrency issues are moe easiyl dealt with...
> > well thats what i unerstood... i may be wrong (2.2 or 2.3 may have
> > changed that)
>
> No, pthreads changed that, from my understanding. linuxthreads did
> it all in one thing w/o ever actually calling the kernel 'clone'. pthreads
> properly calles 'clone' and therefore each thread gets it's own PID and as
> such can be scheduled on any CPU. (Well, that's not the direct reason, but
> you know what I mean).
>

Not quite. Linuxthreads has always used clone and is an attempt to
implement the POSIX threading spec. There has been a number of
pthread implementations over the years that were strictly user space.
I think there is a GNU threads or something like that which is still a
user-space pthread implementation.

>
> > hmmm - when did that change - i know solarids has them run on multiple
> > cpu's though...
>
> Solaris implemented it kernel-level to begin with. The first
> threading in Linux was done all in user-space, IIRC. Which meant that it
> couldn't because a single process (to the kernel) won't get multiple CPUs.
>

Solaris and True64 (AIX as well?) have both user-space thread control
as well as kernel threading which is taken care of by the kernel.
With these you can switch between being user-space and kernel threads,
though I don't see the wisdom in this. The philosophy of these other
platforms are much different than the Linux way of handling threads.

BAPper

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