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SubjectRe: help needed pls. scheduler(kernel 2.6) + hyperthreaded related questions?
Arun Srinivas wrote:
> If the SMT (apart from SMP) support is enabled in the .config file,
> does the kernel recogonize the 2 logical processor as 2 logical or 2
> physical processors?

You shouldn't be able to select SMT if SMP is not enabled.
If SMT and SMP is selected, then the scheduler will recognise
the 2 processors as logical ones.

> Also, as the hyperthreaded processor may schedule 2 threads in the 2
> logical cpu's, and it may not necessarily be form the same process i.e.,
> the 2 thread it schedules may be from the same or from the different
> process.


> So, is there any way I can tell the scheduler (assuming I make the
> scheduler recogonize my 2 threads..i.e., it knows their pid) to schedule
> always my 2 threads @ the same time? How do I go abt it?

Use sched_setaffinity to force each thread onto the particular
CPU. Use sched_setscheduler to acquire a realtime scheduling
policy. Then use mutexes to synchronise your threads so they
run the desired code segment at the same time.

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