powerpc/oprofile: IBM CELL: add SPU event profiling support

This patch adds the SPU event based profiling funcitonality for the
IBM Cell processor.  Previously, the CELL OProfile kernel code supported
PPU event, PPU cycle profiling and SPU cycle profiling.   The addition of
SPU event profiling allows the users to identify where in their SPU code
various SPU evnets are occuring.  This should help users further identify
issues with their code.  Note, SPU profiling has some limitations due to HW
constraints.  Only one event at a time can be used for profiling and SPU event
profiling must be time sliced across all of the SPUs in a node.

The patch adds a new arch specific file to the OProfile file system. The
file has bit 0 set to indicate that the kernel supports SPU event profiling.
The user tool must check this file/bit to make sure the kernel supports
SPU event profiling before trying to do SPU event profiling.  The user tool
check is part of the user tool patch for SPU event profiling.

Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Robert Richter <robert.richter@amd.com>

1 files changed, 32 insertions, 2 deletions

diff --git a/arch/powerpc/oprofile/cell/spu_profiler.c b/arch/powerpc/oprofile/cell/spu_profiler.c
index 8b1b9cc..de170b7 100644
--- a/arch/powerpc/oprofile/cell/spu_profiler.c
+++ b/arch/powerpc/oprofile/cell/spu_profiler.c
@@ -18,11 +18,21 @@
 #include <asm/cell-pmu.h>
 #include "pr_util.h"
 
-#define TRACE_ARRAY_SIZE 1024
 #define SCALE_SHIFT 14
 
 static u32 *samples;
 
+/* spu_prof_running is a flag used to indicate if spu profiling is enabled
+ * or not.  It is set by the routines start_spu_profiling_cycles() and
+ * start_spu_profiling_events().  The flag is cleared by the routines
+ * stop_spu_profiling_cycles() and stop_spu_profiling_events().  These
+ * routines are called via global_start() and global_stop() which are called in
+ * op_powerpc_start() and op_powerpc_stop().  These routines are called once
+ * per system as a result of the user starting/stopping oprofile.  Hence, only
+ * one CPU per user at a time will be changing  the value of spu_prof_running.
+ * In general, OProfile does not protect against multiple users trying to run
+ * OProfile at a time.
+ */
 int spu_prof_running;
 static unsigned int profiling_interval;
 
@@ -31,7 +41,7 @@ static unsigned int profiling_interval;
 
 #define SPU_PC_MASK	     0xFFFF
 
-static DEFINE_SPINLOCK(oprof_spu_smpl_arry_lck);
+DEFINE_SPINLOCK(oprof_spu_smpl_arry_lck);
 unsigned long oprof_spu_smpl_arry_lck_flags;
 
 void set_spu_profiling_frequency(unsigned int freq_khz, unsigned int cycles_reset)
@@ -212,6 +222,21 @@ int start_spu_profiling_cycles(unsigned int cycles_reset)
 	return 0;
 }
 
+/*
+ * Entry point for SPU event profiling.
+ * NOTE:  SPU profiling is done system-wide, not per-CPU.
+ *
+ * cycles_reset is the count value specified by the user when
+ * setting up OProfile to count SPU_CYCLES.
+ */
+void start_spu_profiling_events(void)
+{
+	spu_prof_running = 1;
+	schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
+
+	return;
+}
+
 void stop_spu_profiling_cycles(void)
 {
 	spu_prof_running = 0;
@@ -219,3 +244,8 @@ void stop_spu_profiling_cycles(void)
 	kfree(samples);
 	pr_debug("SPU_PROF: stop_spu_profiling_cycles issued\n");
 }
+
+void stop_spu_profiling_events(void)
+{
+	spu_prof_running = 0;
+}