PR909: Runtime for Performance Event Sampling

Implements a very simple sampling runtime to using the performance
events kernel API. An perf event attribute describing the setup and a
function to handle the counter overflows are passed into
_stp_perf_init(). This function sets up the event on each processor.
If successfully initialized, a pointer data structure is
returned. When the sampling is no longer needed _stp_perf_del() is
called to shutdown the sampling.

 * runtime/perf.h: Add declarations for data structures and functions
 * runtime/perf.c: Remove old perfmon runtime runtime.
   		   Add  _stp_perf_init() and _stp_perf_del() functions.

2 files changed, 69 insertions, 108 deletions

diff --git a/runtime/perf.c b/runtime/perf.c
index 9ac8b481..06ed551a 100644
--- a/runtime/perf.c
+++ b/runtime/perf.c
@@ -1,6 +1,7 @@
 /* -*- linux-c -*- 
  * Perf Functions
  * Copyright (C) 2006 Red Hat Inc.
+ * Copyright (C) 2010 Red Hat Inc.
  *
  * This file is part of systemtap, and is free software.  You can
  * redistribute it and/or modify it under the terms of the GNU General
@@ -11,7 +12,7 @@
 #ifndef _PERF_C_
 #define _PERF_C_
 
-#include <linux/perfmon.h>
+#include <linux/perf_event.h>
 
 #include "perf.h"
 
@@ -19,117 +20,72 @@
  * @brief Implements performance monitoring hardware support
  */
 
-/* TODO fix so this works on SMP machines
- * Need to do context load, register setup, and start on each processor
+/** Initialize performance sampling
+ * Call this during probe initialization to set up performance event sampling
  *
- * Similarly need to stop and unload on each processor
+ * @param attr description of event to sample
+ * @param callback function to call when perf event overflows
  */
-
-/* TODO make this work with sampling. There needs to be a help thread
- * handling the sampling. */
-
-
-static int _stp_pfm_register_setup(void *desc,
-		       struct pfarg_pmc pmc[], int pmc_count,
-		       struct pfarg_pmd pmd[], int pmd_count)
-{
-	int err = 0;
-
-	if (desc == 0) return -EINVAL;
-	err = pfmk_write_pmcs(desc, pmc, pmc_count);
-	if (err) return err;
-	
-	err = pfmk_write_pmds(desc, pmd, pmd_count);
-	return err;
-}
-
-static struct completion c;
-static struct pfarg_load load_args;
-static struct pfarg_start start_args;
-
-/** Sets up the performance monitoring hardware.
- * The locations desc and context point to are modified as
- * side-effects of the setup. desc is a unique pointer used
- * by the various routines.
- * @param desc pointer to void *, handle to describe perfmon config
- * @param context pointer to context information
- * @param pmc, pointer to array describing control register setup
- * @param pmc_count, number of entries in pmc
- * @param pmd, pointer to array describing data register setup
- * @param pmd_count, number of entries in pmd
- * @returns an int, 0 if no errors encountered during setup
- */
-static int _stp_perfmon_setup(void **desc,
-		       struct pfarg_ctx *context,
-		       struct pfarg_pmc pmc[], int pmc_count,
-		       struct pfarg_pmd pmd[], int pmd_count)
+static Perf _stp_perf_init (struct perf_event_attr *attr,
+			    perf_overflow_handler_t callback)
 {
-	int err = 0;
-
-	/* create a context */
-	err = pfmk_create_context(context, NULL, 0, &c, desc, NULL);
-	if (err) goto cleanup;
-
-	/* set up the counters */
-	err = _stp_pfm_register_setup(*desc, pmc, pmc_count, pmd, pmd_count);
-	if (err) goto cleanup2;
-
-	/* start measuring */
-	err = pfmk_load_context(*desc, &load_args);
-	if (err) {
-		printk("pfmk_load_context error\n");
-		goto cleanup2;
+	int cpu;
+	Perf pe;
+
+	pe = (Perf) _stp_kmalloc (sizeof(struct _Perf));
+	if (pe == NULL)
+		return NULL;
+	pe->callback = callback;
+
+	/* allocate space for the event descriptor for each cpu */
+	pe->pd = (struct perf_event **)
+		_stp_alloc_percpu (sizeof(struct perf_event *));
+	if (pe->pd == NULL)
+		goto exit1;
+
+	/* initialize event on each processor */
+	stp_for_each_cpu(cpu) {
+		struct perf_event **event = per_cpu_ptr (pe->pd, cpu);
+		*event = perf_event_create_kernel_counter(attr, cpu, -1,
+							  callback);
+
+		if (IS_ERR(*event)) {
+			*event = NULL;
+			goto exit2;
+		}
 	}
-	err = pfmk_start(*desc, &start_args);
-	if (err) {
-		printk("pfmk_start error\n");
-		goto cleanup3;
-	}
-
-	return err;
-
-cleanup3: pfmk_unload_context(*desc);
-cleanup2: pfmk_close(*desc);
-cleanup: *desc=NULL; 
-	return err;
-}
-
-/** Shuts down the performance monitoring hardware.
- * @param desc unique pointer to describe configuration
- * @returns an int, 0 if no errors encountered during shutdown
- */
-static int _stp_perfmon_shutdown(void *desc)
-{
-	int err=0;
+	return pe;
 
-	if (desc == 0) return -EINVAL;
-	/* stop the counters */
-	err=pfmk_stop(desc);
-	if (err) return err;
-	err=pfmk_unload_context(desc);
-	if (err) return err;
-	err=pfmk_close(desc);
-	return err;
+exit2:
+	stp_for_each_cpu(cpu) {
+		struct perf_event **event = per_cpu_ptr (pe->pd, cpu);
+		if (*event) perf_event_release_kernel(*event);
+	}
+	_stp_free_percpu(pe->pd);
+exit1:
+	_stp_kfree(pe);
+	return NULL;
 }
 
-/** Reads the performance counter
- * @param desc unique pointer to describe configuration
- * @returns an int64, raw value of counter
+/** Delete performance event.
+ * Call this to shutdown performance event sampling
+ *
+ * @param pe
  */
-static int64_t _stp_perfmon_read(void *desc, int counter)
+static void _stp_perf_del (Perf pe)
 {
-	struct pfarg_pmd storage;
-	
-	storage.reg_set = 0;
-	storage.reg_num = counter;
-
-	if ( desc != NULL) {
-		if (pfmk_read_pmds(desc, &storage, 1))
-			printk( "pfm_read_pmds error\n");
+	if (pe) {
+		int cpu;
+		/* shut down performance event sampling */
+		stp_for_each_cpu(cpu) {
+			struct perf_event **event = per_cpu_ptr (pe->pd, cpu);
+			if (*event) {
+				perf_event_release_kernel(*event);
+			}
+		}
+		_stp_free_percpu (pe->pd);
+		_stp_kfree (pe);
 	}
-
-	return storage.reg_value;
 }
 
 #endif /* _PERF_C_ */
-
diff --git a/runtime/perf.h b/runtime/perf.h
index 6a87bff0..32383665 100644
--- a/runtime/perf.h
+++ b/runtime/perf.h
@@ -1,6 +1,7 @@
 /* -*- linux-c -*- 
  * Perf Header File
  * Copyright (C) 2006 Red Hat Inc.
+ * Copyright (C) 2010 Red Hat Inc.
  *
  * This file is part of systemtap, and is free software.  You can
  * redistribute it and/or modify it under the terms of the GNU General
@@ -15,13 +16,17 @@
  * @brief Header file for performance monitoring hardware support
  */
 
-static int _stp_perfmon_setup(void **desc,
-		       struct pfarg_ctx *context,
-		       struct pfarg_pmc pmc[], int pmc_count,
-		       struct pfarg_pmd pmd[], int pmd_count);
+struct _Perf {
+	/* per-cpu data. allocated with _stp_alloc_percpu() */
+	struct perf_event **pd;
+        perf_overflow_handler_t callback;
+};
 
-static int _stp_perfmon_shutdown(void *desc);
+typedef struct _Perf *Perf;
 
-static int64_t _stp_perfmon_read(void *desc, int counter);
+static Perf _stp_perf_init (struct perf_event_attr *attr,
+			    perf_overflow_handler_t callback);
+
+static void _stp_perf_del (Perf pe);
 
 #endif /* _PERF_H_ */