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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.
    >

    Yes.

    > 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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