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Commit 6de6a7b9 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
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perf_counter: add ioctl(PERF_COUNTER_IOC_RESET) 



Provide a way to reset an existing counter - this eases PAPI
libraries around perfcounters.

Similar to read() it doesn't collapse pending child counters.

[ Impact: new perfcounter fd ioctl method to reset counters ]

Suggested-by: default avatarCorey Ashford <cjashfor@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <20090505155437.022272933@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c66de4a5

include/linux/perf_counter.h

+1 −0
Original line number Diff line number Diff line
@@ -160,6 +160,7 @@ struct perf_counter_hw_event { 
#define PERF_COUNTER_IOC_ENABLE		_IO ('$', 0)

#define PERF_COUNTER_IOC_DISABLE	_IO ('$', 1)

#define PERF_COUNTER_IOC_REFRESH	_IOW('$', 2, u32)

#define PERF_COUNTER_IOC_RESET		_IO ('$', 3)



/*

 * Structure of the page that can be mapped via mmap

kernel/perf_counter.c

+8 −0
Original line number Diff line number Diff line
@@ -1288,6 +1288,11 @@ static unsigned int perf_poll(struct file *file, poll_table *wait) 
	return events;

}



static void perf_counter_reset(struct perf_counter *counter)

{

	atomic_set(&counter->count, 0);

}



static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

	struct perf_counter *counter = file->private_data;
@@ -1303,6 +1308,9 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
	case PERF_COUNTER_IOC_REFRESH:

		perf_counter_refresh(counter, arg);

		break;

	case PERF_COUNTER_IOC_RESET:

		perf_counter_reset(counter);

		break;

	default:

		err = -ENOTTY;

	}