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Commit 26b119bc authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: Log irq_period changes 



For the dynamic irq_period code, log whenever we change the period so that
analyzing code can normalize the event flow.

[ Impact: add new feature to allow more precise profiling ]

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090520102553.298769743@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d7b629a3

include/linux/perf_counter.h

+8 −0
Original line number Diff line number Diff line
@@ -257,6 +257,14 @@ enum perf_event_type { 
	 */

	PERF_EVENT_COMM			= 3,



	/*

	 * struct {

	 * 	struct perf_event_header	header;

	 * 	u64				irq_period;

	 * };

	 */

	PERF_EVENT_PERIOD		= 4,



	/*

	 * When header.misc & PERF_EVENT_MISC_OVERFLOW the event_type field

	 * will be PERF_RECORD_*

kernel/perf_counter.c

+39 −1
Original line number Diff line number Diff line
@@ -1046,7 +1046,9 @@ int perf_counter_task_enable(void) 
	return 0;

}



void perf_adjust_freq(struct perf_counter_context *ctx)

static void perf_log_period(struct perf_counter *counter, u64 period);



static void perf_adjust_freq(struct perf_counter_context *ctx)

{

	struct perf_counter *counter;

	u64 irq_period;
@@ -1072,6 +1074,8 @@ void perf_adjust_freq(struct perf_counter_context *ctx) 
		if (!irq_period)

			irq_period = 1;



		perf_log_period(counter, irq_period);



		counter->hw.irq_period = irq_period;

		counter->hw.interrupts = 0;

	}
@@ -2406,6 +2410,40 @@ void perf_counter_munmap(unsigned long addr, unsigned long len, 
	perf_counter_mmap_event(&mmap_event);

}



/*

 *

 */



static void perf_log_period(struct perf_counter *counter, u64 period)

{

	struct perf_output_handle handle;

	int ret;



	struct {

		struct perf_event_header	header;

		u64				time;

		u64				period;

	} freq_event = {

		.header = {

			.type = PERF_EVENT_PERIOD,

			.misc = 0,

			.size = sizeof(freq_event),

		},

		.time = sched_clock(),

		.period = period,

	};



	if (counter->hw.irq_period == period)

		return;



	ret = perf_output_begin(&handle, counter, sizeof(freq_event), 0, 0);

	if (ret)

		return;



	perf_output_put(&handle, freq_event);

	perf_output_end(&handle);

}



/*

 * Generic counter overflow handling.

 */