• Paul Mackerras's avatar
    perf_counter: powerpc: Enable use of software counters on 32-bit powerpc · 105988c0
    Paul Mackerras authored
    This enables the perf_counter subsystem on 32-bit powerpc.  Since we
    don't have any support for hardware counters on 32-bit powerpc yet,
    only software counters can be used.
    
    Besides selecting HAVE_PERF_COUNTERS for 32-bit powerpc as well as
    64-bit, the main thing this does is add an implementation of
    set_perf_counter_pending().  This needs to arrange for
    perf_counter_do_pending() to be called when interrupts are enabled.
    Rather than add code to local_irq_restore as 64-bit does, the 32-bit
    set_perf_counter_pending() generates an interrupt by setting the
    decrementer to 1 so that a decrementer interrupt will become pending
    in 1 or 2 timebase ticks (if a decrementer interrupt isn't already
    pending).  When interrupts are enabled, timer_interrupt() will be
    called, and some new code in there calls perf_counter_do_pending().
    We use a per-cpu array of flags to indicate whether we need to call
    perf_counter_do_pending() or not.
    
    This introduces a couple of new Kconfig symbols: PPC_HAVE_PMU_SUPPORT,
    which is selected by processor families for which we have hardware PMU
    support (currently only PPC64), and PPC_PERF_CTRS, which enables the
    powerpc-specific perf_counter back-end.
    Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: linuxppc-dev@ozlabs.org
    Cc: benh@kernel.crashing.org
    LKML-Reference: <19000.55404.103840.393470@cargo.ozlabs.ibm.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    105988c0
Kconfig 23.6 KB