Commit bf589e32 authored by Robert Richter's avatar Robert Richter
Browse files

oprofile: adding cpu_buffer_entries() 



This is in preparation for changes in the cpu buffer implementation.

Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
parent 229234ae

drivers/oprofile/buffer_sync.c

+2 −29
Original line number Diff line number Diff line
@@ -464,33 +464,6 @@ static inline int is_code(unsigned long val) 
}





/* "acquire" as many cpu buffer slots as we can */

static unsigned long get_slots(struct oprofile_cpu_buffer *b)

{

	unsigned long head = b->head_pos;

	unsigned long tail = b->tail_pos;



	/*

	 * Subtle. This resets the persistent last_task

	 * and in_kernel values used for switching notes.

	 * BUT, there is a small window between reading

	 * head_pos, and this call, that means samples

	 * can appear at the new head position, but not

	 * be prefixed with the notes for switching

	 * kernel mode or a task switch. This small hole

	 * can lead to mis-attribution or samples where

	 * we don't know if it's in the kernel or not,

	 * at the start of an event buffer.

	 */

	cpu_buffer_reset(b);



	if (head >= tail)

		return head - tail;



	return head + (b->buffer_size - tail);

}





/* Move tasks along towards death. Any tasks on dead_tasks

 * will definitely have no remaining references in any

 * CPU buffers at this point, because we use two lists,
@@ -576,11 +549,11 @@ void sync_buffer(int cpu) 
	/* Remember, only we can modify tail_pos */



#ifndef CONFIG_OPROFILE_IBS

	available = get_slots(cpu_buf);

	available = cpu_buffer_entries(cpu_buf);



	for (i = 0; i < available; ++i) {

#else

	while (get_slots(cpu_buf)) {

	while (cpu_buffer_entries(cpu_buf)) {

#endif

		struct op_sample *s = cpu_buffer_read_entry(cpu_buf);

drivers/oprofile/cpu_buffer.h

+27 −0
Original line number Diff line number Diff line
@@ -81,6 +81,33 @@ struct op_sample *cpu_buffer_read_entry(struct oprofile_cpu_buffer *cpu_buf) 
	return &cpu_buf->buffer[cpu_buf->tail_pos];

}



/* "acquire" as many cpu buffer slots as we can */

static inline

unsigned long cpu_buffer_entries(struct oprofile_cpu_buffer *b)

{

	unsigned long head = b->head_pos;

	unsigned long tail = b->tail_pos;



	/*

	 * Subtle. This resets the persistent last_task

	 * and in_kernel values used for switching notes.

	 * BUT, there is a small window between reading

	 * head_pos, and this call, that means samples

	 * can appear at the new head position, but not

	 * be prefixed with the notes for switching

	 * kernel mode or a task switch. This small hole

	 * can lead to mis-attribution or samples where

	 * we don't know if it's in the kernel or not,

	 * at the start of an event buffer.

	 */

	cpu_buffer_reset(b);



	if (head >= tail)

		return head - tail;



	return head + (b->buffer_size - tail);

}



/* transient events for the CPU buffer -> event buffer */

#define CPU_IS_KERNEL 1

#define CPU_TRACE_BEGIN 2