On Tue, Mar 29, 2005 at 10:26:04AM -0800, Tim Rowledge wrote:
> Ross Boylan <RossBoylan at stanfordalumni.org> wrote:
...
 
> > So John's  earlier statement that
> > > [P]rocessing switching can occur ....
> > > on a primitive call if  when the call takes > 1 or perhaps 17ms  
> > > depending on platform.
> > does not reflect current behavior?
> Yes and no :-) For quite a long time there was code in the prim calling
> routines that checked the time before calling a prim and after the
> prims and if the delta was high enough it would force a process
> > switch

There's the key I missed: if a primitive takes a long time there is a
yield opportunity *after* it returns.  I thought the statement meant
that if 1ms passed and the call had not returned, the VM would switch
to something else.

Thanks for the details on the 3.8 VM changes (snipped).