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SubjectRe: Threading...
On Fri, 19 Jan 2007 19:55:41 +0100, Arjan van de Ven <> wrote:

> On Fri, 2007-01-19 at 10:43 -0800, Brian McGrew wrote:
> > I have a very interesting question about something that we're seeing
> > happening with threading between Fedora Core 3 and Fedora Core 5. Running
> > on Dell PowerEdge 1800 Hardware with a Xeon processor with hyper-threading
> > turned on. Both systems are using a kernel (MVP al la special).
> >
> > We have a multithreaded application that starts two worker threads. On
> > Fedora Core 3 both of these we use getpid() to get the PID of the thread and
> > then use set_afinity to assign each thread to it's own CPU. Both threads
> > run almost symmetrically even on their given CPU watching the system
> > monitor.
> this is odd; even in FC3 getpid() is supposed to return the process ID
> not the thread ID
> > What am I missing? What do I need to do in FC5 or the kernel or the
> > threading library to get my threads to run in symmetric parallel again???

One thing to try. In linux, pthread_setconcurrency never did nothing
(it _really_ did in IRIX...). Can you try that ? Perhaps FC5 has implemented
some kind of scheduling policy like that on irix (everything stays on the
same CPU until it starts to suck cycles, unless you use setconcurrency).

J.A. Magallon <jamagallon()ono!com> \ Software is like sex:
\ It's better when it's free
Mandriva Linux release 2007.1 (Cooker) for i586
Linux 2.6.19-jam04 (gcc 4.1.2 20061110 (prerelease) (4.1.2-0.20061110.2mdv2007.1)) #0 SMP PREEMPT
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