Re: [RFC][PATCH 10/11] perf: Shrink hw_perf_event

Frederic Weisbecker
2010-06-29T15:06:28Z

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);
> }
>
>