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Postings from January 2002
At 09:30 AM 1/1/2002 -0800, Benjamin Stuhl wrote:
>--- Dan Sugalski <dan@sidhe.org> wrote:
> > At 07:30 AM 12/30/2001 -1000, David & Lisa Jacobs wrote:
> >
> > >From: "Dan Sugalski" <dan@sidhe.org>
> > > > At 08:33 PM 12/29/2001 -1000, David & Lisa Jacobs
> > wrote:
> > > > GC will manage all the memory. Everything managed
> > should either be hung
> > >off
> > > > a PMC or an internal structure. (There are GC hooks
> > in the vtable for
> > > > complex things)
> > >
> > >So does that mean I can get rid of passing around the
> > interpreter?
> >
> > Sort of. Memory and structure (pmc header & string
> > header) allocation must
> > be from interpreter-local pools. There's a patch to use
> > TLS for the
> > interpreter pointer rather than passing it as an
> > argument--I've pretty much
> > decided it's The Way To Go, so I'm going to dig it out
> > and apply it.
> >
> > So you still need the interpreter pointer, you just don't
> > have to pass it.
>
>Are you really sure about this?
Yes.
>The reason perl5 threads
>are MULTIPLICITY-based (pass around an interpreter pointer)
>is that Sarathy got a noticeable speedup from not having to
>call pthread_getspecific() every time he needed to allocate
>memory or look up a symbol.
Perl 5 is hampered by its past in a lot of places. This would be one of
them. Sarathy's decision on how to go was constrained by perl's current
design. And personal preference, but that goes without saying for any
designer. Perl 5 called pthread_getspecific far too many times. I put in a
patch to use the unchecked version on VMS & Tru64 Unix and got an insane
speedup. (And we will use the same trick with parrot, 'cause I'm officially
Evil :) It was caused in part by perl's macro-itis. It was getting called
in a lot of places it didn't need to be.
Passing around extra parameters is costlier than you'd think. (Like ~5-10%
of function call time) Anyway, we'll benchmark things and see what's best.
Dan
--------------------------------------"it's like this"-------------------
Dan Sugalski even samurai
dan@sidhe.org have teddy bears and even
teddy bears get drunk
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