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    SubjectRe: [RFC][PATCH 10/11] perf: Shrink hw_perf_event
    On Thu, Jun 24, 2010 at 04:28:14PM +0200, Peter Zijlstra wrote:
    > Use hw_perf_event::period_left instead of hw_perf_event::remaning and
    > win back 8 bytes.
    >
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>


    Acked-by: Frederic Weisbecker <fweisbec@gmail.com>



    > ---
    > include/linux/perf_event.h | 1 -
    > kernel/perf_event.c | 13 ++++++-------
    > 2 files changed, 6 insertions(+), 8 deletions(-)
    >
    > Index: linux-2.6/include/linux/perf_event.h
    > ===================================================================
    > --- linux-2.6.orig/include/linux/perf_event.h
    > +++ linux-2.6/include/linux/perf_event.h
    > @@ -529,7 +529,6 @@ struct hw_perf_event {
    > int last_cpu;
    > };
    > struct { /* software */
    > - s64 remaining;
    > struct hrtimer hrtimer;
    > };
    > #ifdef CONFIG_HAVE_HW_BREAKPOINT
    > Index: linux-2.6/kernel/perf_event.c
    > ===================================================================
    > --- linux-2.6.orig/kernel/perf_event.c
    > +++ linux-2.6/kernel/perf_event.c
    > @@ -4590,14 +4590,13 @@ static void perf_swevent_start_hrtimer(s
    > hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    > hwc->hrtimer.function = perf_swevent_hrtimer;
    > if (hwc->sample_period) {
    > - u64 period;
    > + s64 period = local64_read(&hwc->period_left);
    >
    > - if (hwc->remaining) {
    > - if (hwc->remaining < 0)
    > + if (period) {
    > + if (period < 0)
    > period = 10000;
    > - else
    > - period = hwc->remaining;
    > - hwc->remaining = 0;
    > +
    > + local64_set(&hwc->period_left, 0);
    > } else {
    > period = max_t(u64, 10000, hwc->sample_period);
    > }
    > @@ -4613,7 +4612,7 @@ static void perf_swevent_cancel_hrtimer(
    >
    > if (hwc->sample_period) {
    > ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer);
    > - hwc->remaining = ktime_to_ns(remaining);
    > + local64_set(&hwc->period_left, ktime_to_ns(remaining));
    >
    > hrtimer_cancel(&hwc->hrtimer);
    > }
    >
    >



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