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Commit 211117ff authored by Robert Richter's avatar Robert Richter
Browse files

oprofile: fix lost sample counter 



The number of lost samples could be greater than the number of
received samples. This patches fixes this. The implementation
introduces return values for add_sample() and add_code().

Signed-off-by: default avatarRobert Richter <robert.richter@amd.com>
parent 1d7503b5

drivers/oprofile/cpu_buffer.c

+53 −30
Original line number Diff line number Diff line
@@ -145,32 +145,31 @@ void end_cpu_work(void) 
	flush_scheduled_work();

}



static inline void

static inline int

add_sample(struct oprofile_cpu_buffer *cpu_buf,

	   unsigned long pc, unsigned long event)

{

	struct op_entry entry;

	int ret;



	if (cpu_buffer_write_entry(&entry))

		goto Error;

	ret = cpu_buffer_write_entry(&entry);

	if (ret)

		return ret;



	entry.sample->eip = pc;

	entry.sample->event = event;



	if (cpu_buffer_write_commit(&entry))

		goto Error;

	ret = cpu_buffer_write_commit(&entry);

	if (ret)

		return ret;



	return;



Error:

	cpu_buf->sample_lost_overflow++;

	return;

	return 0;

}



static inline void

static inline int

add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)

{

	add_sample(buffer, ESCAPE_CODE, value);

	return add_sample(buffer, ESCAPE_CODE, value);

}



/* This must be safe from any context. It's safe writing here
@@ -201,17 +200,25 @@ static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc, 
	/* notice a switch from user->kernel or vice versa */

	if (cpu_buf->last_is_kernel != is_kernel) {

		cpu_buf->last_is_kernel = is_kernel;

		add_code(cpu_buf, is_kernel);

		if (add_code(cpu_buf, is_kernel))

			goto fail;

	}



	/* notice a task switch */

	if (cpu_buf->last_task != task) {

		cpu_buf->last_task = task;

		add_code(cpu_buf, (unsigned long)task);

		if (add_code(cpu_buf, (unsigned long)task))

			goto fail;

	}



	add_sample(cpu_buf, pc, event);

	if (add_sample(cpu_buf, pc, event))

		goto fail;



	return 1;



fail:

	cpu_buf->sample_lost_overflow++;

	return 0;

}



static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
@@ -266,37 +273,49 @@ void oprofile_add_ibs_sample(struct pt_regs * const regs, 
	int is_kernel = !user_mode(regs);

	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

	struct task_struct *task;

	int fail = 0;



	cpu_buf->sample_received++;



	/* notice a switch from user->kernel or vice versa */

	if (cpu_buf->last_is_kernel != is_kernel) {

		if (add_code(cpu_buf, is_kernel))

			goto fail;

		cpu_buf->last_is_kernel = is_kernel;

		add_code(cpu_buf, is_kernel);

	}



	/* notice a task switch */

	if (!is_kernel) {

		task = current;

		if (cpu_buf->last_task != task) {

			if (add_code(cpu_buf, (unsigned long)task))

				goto fail;

			cpu_buf->last_task = task;

			add_code(cpu_buf, (unsigned long)task);

		}

	}



	add_code(cpu_buf, ibs_code);

	add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);

	add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);

	add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);

	fail = fail || add_code(cpu_buf, ibs_code);

	fail = fail || add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);

	fail = fail || add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);

	fail = fail || add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);



	if (ibs_code == IBS_OP_BEGIN) {

		add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);

		add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);

		add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);

		fail = fail || add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);

		fail = fail || add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);

		fail = fail || add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);

	}



	if (fail)

		goto fail;



	if (backtrace_depth)

		oprofile_ops.backtrace(regs, backtrace_depth);



	return;



fail:

	cpu_buf->sample_lost_overflow++;

	return;

}



#endif
@@ -318,15 +337,19 @@ void oprofile_add_trace(unsigned long pc) 
	 * broken frame can give an eip with the same value as an

	 * escape code, abort the trace if we get it

	 */

	if (pc == ESCAPE_CODE) {

	if (pc == ESCAPE_CODE)

		goto fail;



	if (add_sample(cpu_buf, pc, 0))

		goto fail;



	return;

fail:

	cpu_buf->tracing = 0;

	cpu_buf->backtrace_aborted++;

	return;

}



	add_sample(cpu_buf, pc, 0);

}



/*

 * This serves to avoid cpu buffer overflow, and makes sure

 * the task mortuary progresses