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Commit 8e3747c1 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: Change data head from u32 to u64 



Since some people worried that 4G might not be a large enough
as an mmap data window, extend it to 64 bit for capable
platforms.

Reported-by: default avatarStephane Eranian <eranian@googlemail.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e4abb5d4

include/linux/perf_counter.h

+4 −3
Original line number Original line Diff line number Diff line
@@ -212,7 +212,7 @@ struct perf_counter_mmap_page { 
	 * User-space reading this value should issue an rmb(), on SMP capable

	 * User-space reading this value should issue an rmb(), on SMP capable

	 * platforms, after reading this value -- see perf_counter_wakeup().

	 * platforms, after reading this value -- see perf_counter_wakeup().

	 */

	 */

	__u32   data_head;		/* head in the data section */

	__u64   data_head;		/* head in the data section */

};

};





#define PERF_EVENT_MISC_CPUMODE_MASK	(3 << 0)

#define PERF_EVENT_MISC_CPUMODE_MASK	(3 << 0)
@@ -397,10 +397,11 @@ struct perf_mmap_data { 
	int				nr_locked;	/* nr pages mlocked  */

	int				nr_locked;	/* nr pages mlocked  */





	atomic_t			poll;		/* POLL_ for wakeups */

	atomic_t			poll;		/* POLL_ for wakeups */

	atomic_t			head;		/* write position    */

	atomic_t			events;		/* event limit       */

	atomic_t			events;		/* event limit       */





	atomic_t			done_head;	/* completed head    */

	atomic_long_t			head;		/* write position    */

	atomic_long_t			done_head;	/* completed head    */



	atomic_t			lock;		/* concurrent writes */

	atomic_t			lock;		/* concurrent writes */





	atomic_t			wakeup;		/* needs a wakeup    */

	atomic_t			wakeup;		/* needs a wakeup    */

kernel/perf_counter.c

+8 −7
Original line number Original line Diff line number Diff line
@@ -2067,8 +2067,8 @@ __weak struct perf_callchain_entry *perf_callchain(struct pt_regs *regs) 
struct perf_output_handle {

struct perf_output_handle {

	struct perf_counter	*counter;

	struct perf_counter	*counter;

	struct perf_mmap_data	*data;

	struct perf_mmap_data	*data;

	unsigned int		offset;

	unsigned long		head;

	unsigned int		head;

	unsigned long		offset;

	int			nmi;

	int			nmi;

	int			overflow;

	int			overflow;

	int			locked;

	int			locked;
@@ -2122,7 +2122,8 @@ static void perf_output_lock(struct perf_output_handle *handle) 
static void perf_output_unlock(struct perf_output_handle *handle)

static void perf_output_unlock(struct perf_output_handle *handle)

{

{

	struct perf_mmap_data *data = handle->data;

	struct perf_mmap_data *data = handle->data;

	int head, cpu;

	unsigned long head;

	int cpu;





	data->done_head = data->head;

	data->done_head = data->head;
@@ -2135,7 +2136,7 @@ static void perf_output_unlock(struct perf_output_handle *handle) 
	 * before we publish the new head, matched by a rmb() in userspace when

	 * before we publish the new head, matched by a rmb() in userspace when

	 * reading this position.

	 * reading this position.

	 */

	 */

	while ((head = atomic_xchg(&data->done_head, 0)))

	while ((head = atomic_long_xchg(&data->done_head, 0)))

		data->user_page->data_head = head;

		data->user_page->data_head = head;





	/*

	/*
@@ -2148,7 +2149,7 @@ static void perf_output_unlock(struct perf_output_handle *handle) 
	/*

	/*

	 * Therefore we have to validate we did not indeed do so.

	 * Therefore we have to validate we did not indeed do so.

	 */

	 */

	if (unlikely(atomic_read(&data->done_head))) {

	if (unlikely(atomic_long_read(&data->done_head))) {

		/*

		/*

		 * Since we had it locked, we can lock it again.

		 * Since we had it locked, we can lock it again.

		 */

		 */
@@ -2195,7 +2196,7 @@ static int perf_output_begin(struct perf_output_handle *handle, 
	do {

	do {

		offset = head = atomic_read(&data->head);

		offset = head = atomic_read(&data->head);

		head += size;

		head += size;

	} while (atomic_cmpxchg(&data->head, offset, head) != offset);

	} while (atomic_long_cmpxchg(&data->head, offset, head) != offset);





	handle->offset	= offset;

	handle->offset	= offset;

	handle->head	= head;

	handle->head	= head;
@@ -2246,7 +2247,7 @@ static void perf_output_copy(struct perf_output_handle *handle, 
	 * Check we didn't copy past our reservation window, taking the

	 * Check we didn't copy past our reservation window, taking the

	 * possible unsigned int wrap into account.

	 * possible unsigned int wrap into account.

	 */

	 */

	WARN_ON_ONCE(((int)(handle->head - handle->offset)) < 0);

	WARN_ON_ONCE(((long)(handle->head - handle->offset)) < 0);

}

}





#define perf_output_put(handle, x) \

#define perf_output_put(handle, x) \