Systemtap perfmon support to access the processors perfmon hardware.

1 files changed, 135 insertions, 0 deletions

diff --git a/runtime/perf.c b/runtime/perf.c
new file mode 100644
index 00000000..0b812630
--- /dev/null
+++ b/runtime/perf.c
@@ -0,0 +1,135 @@
+/* -*- linux-c -*- 
+ * Perf Functions
+ * Copyright (C) 2006 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
+ * Public License (GPL); either version 2, or (at your option) any
+ * later version.
+ */
+
+#ifndef _PERF_C_
+#define _PERF_C_
+
+#include <linux/perfmon.h>
+
+#include "perf.h"
+
+/** @file perf.c
+ * @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
+ *
+ * Similarly need to stop and unload on each processor
+ */
+
+/* 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
+ */
+int _stp_perfmon_setup(void **desc,
+		       struct pfarg_ctx *context,
+		       struct pfarg_pmc pmc[], int pmc_count,
+		       struct pfarg_pmd pmd[], int pmd_count)
+{
+	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;
+	}
+	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
+ */
+int _stp_perfmon_shutdown(void *desc)
+{
+	int err=0;
+
+	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;
+}
+
+/** Reads the performance counter
+ * @param desc unique pointer to describe configuration
+ * @returns an int64, raw value of counter
+ */
+int64_t _stp_perfmon_read(void *desc, int counter)
+{
+	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");
+	}
+
+	return storage.reg_value;
+}
+
+#endif /* _PERF_C_ */
+