• Martin Schwidefsky's avatar
    s390: add SMT support · 10ad34bc
    Martin Schwidefsky authored
    The multi-threading facility is introduced with the z13 processor family.
    This patch adds code to detect the multi-threading facility. With the
    facility enabled each core will surface multiple hardware threads to the
    system. Each hardware threads looks like a normal CPU to the operating
    system with all its registers and properties.
    
    The SCLP interface reports the SMT topology indirectly via the maximum
    thread id. Each reported CPU in the result of a read-scp-information
    is a core representing a number of hardware threads.
    
    To reflect the reduced CPU capacity if two hardware threads run on a
    single core the MT utilization counter set is used to normalize the
    raw cputime obtained by the CPU timer deltas. This scaled cputime is
    reported via the taskstats interface. The normal /proc/stat numbers
    are based on the raw cputime and are not affected by the normalization.
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    10ad34bc
smp.h 2.01 KB