• Nicholas Piggin's avatar
    powerpc/pseries: lparcfg calculate PURR on demand · 3d3a6021
    Nicholas Piggin authored
    For SPLPAR, lparcfg provides a sum of PURR registers for all CPUs.
    Currently this is done by reading PURR in context switch and timer
    interrupt, and storing that into a per-CPU variable. These are summed
    to provide the value.
    
    This does not work with all timer schemes (e.g., NO_HZ_FULL), and it
    is sub-optimal for performance because it reads the PURR register on
    every context switch, although that's been difficult to distinguish
    from noise in the contxt_switch microbenchmark.
    
    This patch implements the sum by calling a function on each CPU, to
    read and add PURR values of each CPU.
    Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    3d3a6021
time.h 4.69 KB