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authorJason Yeh <jason.yeh@amd.com>2009-07-08 15:49:38 +0400
committerRobert Richter <robert.richter@amd.com>2009-07-20 18:33:53 +0400
commit4d4036e0e7299c6cbb2d2421b4b30b7a409ce61a (patch)
treec9003cd927ed878412e89a59db0138b6b701b629 /drivers
parent6e63ea4b0b14ff5fb8a3ca704fcda7d28b95f079 (diff)
downloadlinux-4d4036e0e7299c6cbb2d2421b4b30b7a409ce61a.tar.xz
oprofile: Implement performance counter multiplexing
The number of hardware counters is limited. The multiplexing feature enables OProfile to gather more events than counters are provided by the hardware. This is realized by switching between events at an user specified time interval. A new file (/dev/oprofile/time_slice) is added for the user to specify the timer interval in ms. If the number of events to profile is higher than the number of hardware counters available, the patch will schedule a work queue that switches the event counter and re-writes the different sets of values into it. The switching mechanism needs to be implemented for each architecture to support multiplexing. This patch only implements AMD CPU support, but multiplexing can be easily extended for other models and architectures. There are follow-on patches that rework parts of this patch. Signed-off-by: Jason Yeh <jason.yeh@amd.com> Signed-off-by: Robert Richter <robert.richter@amd.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/oprofile/oprof.c78
-rw-r--r--drivers/oprofile/oprof.h2
-rw-r--r--drivers/oprofile/oprofile_files.c43
-rw-r--r--drivers/oprofile/oprofile_stats.c10
4 files changed, 133 insertions, 0 deletions
diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
index 3cffce90f82a..7bc64af7cf99 100644
--- a/drivers/oprofile/oprof.c
+++ b/drivers/oprofile/oprof.c
@@ -12,6 +12,8 @@
#include <linux/init.h>
#include <linux/oprofile.h>
#include <linux/moduleparam.h>
+#include <linux/workqueue.h>
+#include <linux/time.h>
#include <asm/mutex.h>
#include "oprof.h"
@@ -27,6 +29,15 @@ unsigned long oprofile_backtrace_depth;
static unsigned long is_setup;
static DEFINE_MUTEX(start_mutex);
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+
+static void switch_worker(struct work_struct *work);
+static DECLARE_DELAYED_WORK(switch_work, switch_worker);
+unsigned long timeout_jiffies;
+#define MULTIPLEXING_TIMER_DEFAULT 1
+
+#endif
+
/* timer
0 - use performance monitoring hardware if available
1 - use the timer int mechanism regardless
@@ -87,6 +98,20 @@ out:
return err;
}
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+
+static void start_switch_worker(void)
+{
+ schedule_delayed_work(&switch_work, timeout_jiffies);
+}
+
+static void switch_worker(struct work_struct *work)
+{
+ if (!oprofile_ops.switch_events())
+ start_switch_worker();
+}
+
+#endif
/* Actually start profiling (echo 1>/dev/oprofile/enable) */
int oprofile_start(void)
@@ -108,6 +133,11 @@ int oprofile_start(void)
if ((err = oprofile_ops.start()))
goto out;
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+ if (oprofile_ops.switch_events)
+ start_switch_worker();
+#endif
+
oprofile_started = 1;
out:
mutex_unlock(&start_mutex);
@@ -123,6 +153,11 @@ void oprofile_stop(void)
goto out;
oprofile_ops.stop();
oprofile_started = 0;
+
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+ cancel_delayed_work_sync(&switch_work);
+#endif
+
/* wake up the daemon to read what remains */
wake_up_buffer_waiter();
out:
@@ -155,6 +190,36 @@ post_sync:
mutex_unlock(&start_mutex);
}
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+
+/* User inputs in ms, converts to jiffies */
+int oprofile_set_timeout(unsigned long val_msec)
+{
+ int err = 0;
+
+ mutex_lock(&start_mutex);
+
+ if (oprofile_started) {
+ err = -EBUSY;
+ goto out;
+ }
+
+ if (!oprofile_ops.switch_events) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ timeout_jiffies = msecs_to_jiffies(val_msec);
+ if (timeout_jiffies == MAX_JIFFY_OFFSET)
+ timeout_jiffies = msecs_to_jiffies(MULTIPLEXING_TIMER_DEFAULT);
+
+out:
+ mutex_unlock(&start_mutex);
+ return err;
+
+}
+
+#endif
int oprofile_set_backtrace(unsigned long val)
{
@@ -179,10 +244,23 @@ out:
return err;
}
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+
+static void __init oprofile_multiplexing_init(void)
+{
+ timeout_jiffies = msecs_to_jiffies(MULTIPLEXING_TIMER_DEFAULT);
+}
+
+#endif
+
static int __init oprofile_init(void)
{
int err;
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+ oprofile_multiplexing_init();
+#endif
+
err = oprofile_arch_init(&oprofile_ops);
if (err < 0 || timer) {
diff --git a/drivers/oprofile/oprof.h b/drivers/oprofile/oprof.h
index c288d3c24b50..ee38abcc74f3 100644
--- a/drivers/oprofile/oprof.h
+++ b/drivers/oprofile/oprof.h
@@ -27,6 +27,7 @@ extern unsigned long oprofile_buffer_watershed;
extern struct oprofile_operations oprofile_ops;
extern unsigned long oprofile_started;
extern unsigned long oprofile_backtrace_depth;
+extern unsigned long timeout_jiffies;
struct super_block;
struct dentry;
@@ -35,5 +36,6 @@ void oprofile_create_files(struct super_block *sb, struct dentry *root);
void oprofile_timer_init(struct oprofile_operations *ops);
int oprofile_set_backtrace(unsigned long depth);
+int oprofile_set_timeout(unsigned long time);
#endif /* OPROF_H */
diff --git a/drivers/oprofile/oprofile_files.c b/drivers/oprofile/oprofile_files.c
index 5d36ffc30dd5..468ec3e4f856 100644
--- a/drivers/oprofile/oprofile_files.c
+++ b/drivers/oprofile/oprofile_files.c
@@ -9,6 +9,7 @@
#include <linux/fs.h>
#include <linux/oprofile.h>
+#include <linux/jiffies.h>
#include "event_buffer.h"
#include "oprofile_stats.h"
@@ -22,6 +23,45 @@ unsigned long oprofile_buffer_size;
unsigned long oprofile_cpu_buffer_size;
unsigned long oprofile_buffer_watershed;
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+
+static ssize_t timeout_read(struct file *file, char __user *buf,
+ size_t count, loff_t *offset)
+{
+ return oprofilefs_ulong_to_user(jiffies_to_msecs(timeout_jiffies),
+ buf, count, offset);
+}
+
+
+static ssize_t timeout_write(struct file *file, char const __user *buf,
+ size_t count, loff_t *offset)
+{
+ unsigned long val;
+ int retval;
+
+ if (*offset)
+ return -EINVAL;
+
+ retval = oprofilefs_ulong_from_user(&val, buf, count);
+ if (retval)
+ return retval;
+
+ retval = oprofile_set_timeout(val);
+
+ if (retval)
+ return retval;
+ return count;
+}
+
+
+static const struct file_operations timeout_fops = {
+ .read = timeout_read,
+ .write = timeout_write,
+};
+
+#endif
+
+
static ssize_t depth_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
return oprofilefs_ulong_to_user(oprofile_backtrace_depth, buf, count,
@@ -139,6 +179,9 @@ void oprofile_create_files(struct super_block *sb, struct dentry *root)
oprofilefs_create_file(sb, root, "cpu_type", &cpu_type_fops);
oprofilefs_create_file(sb, root, "backtrace_depth", &depth_fops);
oprofilefs_create_file(sb, root, "pointer_size", &pointer_size_fops);
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+ oprofilefs_create_file(sb, root, "time_slice", &timeout_fops);
+#endif
oprofile_create_stats_files(sb, root);
if (oprofile_ops.create_files)
oprofile_ops.create_files(sb, root);
diff --git a/drivers/oprofile/oprofile_stats.c b/drivers/oprofile/oprofile_stats.c
index 3c2270a8300c..77a57a6792f6 100644
--- a/drivers/oprofile/oprofile_stats.c
+++ b/drivers/oprofile/oprofile_stats.c
@@ -16,6 +16,9 @@
#include "cpu_buffer.h"
struct oprofile_stat_struct oprofile_stats;
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+atomic_t multiplex_counter;
+#endif
void oprofile_reset_stats(void)
{
@@ -34,6 +37,9 @@ void oprofile_reset_stats(void)
atomic_set(&oprofile_stats.sample_lost_no_mapping, 0);
atomic_set(&oprofile_stats.event_lost_overflow, 0);
atomic_set(&oprofile_stats.bt_lost_no_mapping, 0);
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+ atomic_set(&multiplex_counter, 0);
+#endif
}
@@ -76,4 +82,8 @@ void oprofile_create_stats_files(struct super_block *sb, struct dentry *root)
&oprofile_stats.event_lost_overflow);
oprofilefs_create_ro_atomic(sb, dir, "bt_lost_no_mapping",
&oprofile_stats.bt_lost_no_mapping);
+#ifdef CONFIG_OPROFILE_EVENT_MULTIPLEX
+ oprofilefs_create_ro_atomic(sb, dir, "multiplex_counter",
+ &multiplex_counter);
+#endif
}