linux-kernel - [PATCH 3/9] oprofile: adding cpu_buffer

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Date:	Thu, 11 Dec 2008 17:41:57 +0100
From:	Robert Richter <robert.richter@....com>
To:	LKML <linux-kernel@...r.kernel.org>
CC:	oprofile-list <oprofile-list@...ts.sourceforge.net>,
	Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Robert Richter <robert.richter@....com>
Subject: [PATCH 3/9] oprofile: adding cpu_buffer_entries()

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

Signed-off-by: Robert Richter <robert.richter@....com>
---
 drivers/oprofile/buffer_sync.c |   31 ++-----------------------------
 drivers/oprofile/cpu_buffer.h  |   27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/drivers/oprofile/buffer_sync.c b/drivers/oprofile/buffer_sync.c
index 44f676c..aed286c 100644
--- a/drivers/oprofile/buffer_sync.c
+++ b/drivers/oprofile/buffer_sync.c
@@ -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);
 
diff --git a/drivers/oprofile/cpu_buffer.h b/drivers/oprofile/cpu_buffer.h
index e608976..6055b56 100644
--- a/drivers/oprofile/cpu_buffer.h
+++ b/drivers/oprofile/cpu_buffer.h
@@ -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
-- 
1.6.0.1


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