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Re: pthread processor binding


I agree with what your saying Andrew. Perhaps if I
disable timeslicing I can ensure a thread will run
until completion (or until locality is no longer a
concern) before yielding the processor. I'd have to
make sure starvation doesn't occur though for some
threads.

This is possible though, right?

Ahmed

--- Andrew Lunn <andrew@lunn.ch> wrote:

> On Wed, Feb 14, 2007 at 04:07:56PM -0800, Ahmed
> Abdelkhalek wrote:
> > Hi everyone,
> > 
> > Some pthread implementations allow binding a
> thread
> > for execution on a particular processor or a set
> of
> > processors (google pthread_pset_bind_np). Are
> there
> > plans to include this in future ecos realeases?
> 
> Just thinking aloud here...
> 
> With an ROTS, which implements prioritized threads,
> the scheduler runs
> the highest priority runnable thread. With SMP, it
> runs the highest
> priority runnable threads, which could potentially
> be at different
> priorities, but i don't think that really matters.
> You probably get
> better performance if you have some level of
> processor affinity,
> i.e. if possible run a thread on the same CPU as it
> was run last time,
> with the hope it still has something useful in the
> cache. However a
> runnable thread should not be left runnable but not
> run because the
> last CPU it ran on is busy when another CPU is
> available. If you did
> leave the thread runnable, you have to either leave
> the CPU unused,
> which is probably wasteful or run a thread of lower
> priority. That
> goes against the principle of the highest priority
> runnable threads
> are the once that runs.
> 
> So to me, it seems like in an SMP RTOS, binding
> threads to processors
> to will actually hinder RT operation.
> 
>    Andrew
> 



 
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