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events: Move lockless timer calculation into helper function 

Take the timer calculation from perf_output_read and move it to a helper
function for any place that needs timer values but cannot take the ctx->lock.

Signed-off-by: Eric B Munson <emunson@mgebm.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1308861279-15216-2-git-send-email-emunson@mgebm.net
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Eric B Munson 2011-06-23 16:34:38 -04:00 committed by Ingo Molnar
parent b7526f0ca6
commit c479429591
1 changed files with 15 additions and 7 deletions
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22
kernel/events/core.c
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@ -3351,6 +3351,18 @@ static int perf_event_index(struct perf_event *event)
return event->hw.idx + 1 - PERF_EVENT_INDEX_OFFSET;
}
static void calc_timer_values(struct perf_event *event,
u64 *running,
u64 *enabled)
{
u64 now, ctx_time;
now = perf_clock();
ctx_time = event->shadow_ctx_time + now;
*enabled = ctx_time - event->tstamp_enabled;
*running = ctx_time - event->tstamp_running;
}
/*
* Callers need to ensure there can be no nesting of this function, otherwise
* the seqlock logic goes bad. We can not serialize this because the arch
@ -3816,7 +3828,7 @@ static void perf_output_read_group(struct perf_output_handle *handle,
static void perf_output_read(struct perf_output_handle *handle,
struct perf_event *event)
{
u64 enabled = 0, running = 0, now, ctx_time;
u64 enabled = 0, running = 0;
u64 read_format = event->attr.read_format;
/*
@ -3828,12 +3840,8 @@ static void perf_output_read(struct perf_output_handle *handle,
* because of locking issue as we are called in
* NMI context
*/
if (read_format & PERF_FORMAT_TOTAL_TIMES) {
now = perf_clock();
ctx_time = event->shadow_ctx_time + now;
enabled = ctx_time - event->tstamp_enabled;
running = ctx_time - event->tstamp_running;
}
if (read_format & PERF_FORMAT_TOTAL_TIMES)
calc_timer_values(event, &enabled, &running);
if (event->attr.read_format & PERF_FORMAT_GROUP)
perf_output_read_group(handle, event, enabled, running);