On Thu, Mar 30, 2006 at 01:16:08PM +0100, Claus Reinke wrote:
> >It is not like inserting yields needs to be done much at all since we have
> >progress guarentees, so we know the program is doing something and on
> >any blocking call that could potentially take a while, the library will
> >yield for you.
>
> where do we get the progress guarantees from? do we need a
> "yield-analysis"? something that will automatically insert yields
> in the code after every n atomic steps, and complain if it cannot
> infer that some piece of code is atomic, but cannot insert a yield
> either? how much of the burden do you want to shift from the
> implementer to the programmer?
no, because there are only certain defined actions that can switch a
thread's state from 'runnable' to 'not-runnable'. In order to
meet the progress guarentee you just need to make sure that when the
current thread switches from 'runnable' to 'not-runnable' that another
thread is chosen.
examples of these points would be:
- calling a foreign concurrent import
- waiting for input on a handle
- waiting for a UNIX signal
- changing thread priorities (possibly)
in any case, the compiler need do nothing special in general, it is
basically a library issue.
John
--
John Meacham - ⑆repetae.net⑆john⑈
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