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    SubjectRe: [PATCH] scripts/checksyscalls.sh: only whine perf_counter_open when supported
    On Fri, Jun 12, 2009 at 08:05, Ingo Molnar wrote:
    > * Mike Frysinger <vapier@gentoo.org> wrote:
    >> If the port does not support HAVE_PERF_COUNTERS, then they can't
    >> support the perf_counter_open syscall either.  Rather than forcing
    >> everyone to add an ignore (or suffer the warning until they get
    >> around to implementing support), only whine about the syscall when
    >> applicable.
    >
    > No, this patch is wrong - it's really easy to add support: just hook
    > up the syscall. This should happen for every architecture really, so
    > the warning is correct and it should not be patched out.
    >
    > PMU support is not required to get perfcounters support: if an
    > architecture hooks up the syscall it will get generic software
    > counters and the tools will work as well.
    >
    > Profiling falls back to a hrtimer-based sampling method - this is a
    > much better fallback than oprofile's fall-back to the timer tick.
    > This hrtimer based sampling is dynticks/nohz-correct and can go
    > beyond HZ if the architecture supports hrtimers.

    if there is generic support available, why must every arch select
    HAVE_PERF_COUNTERS in their Kconfig ?
    -mike
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