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Date: Fri, 7 Sep 2012 16:29:28 +0200
From: Stephane Eranian <eranian@...gle.com>
To: linux-kernel@...r.kernel.org
Cc: peterz@...radead.org, mingo@...e.hu, ak@...ux.intel.com,
zheng.z.yan@...el.com, robert.richter@....com
Subject: [PATCH 2/3] perf: add sysctl control to adjust multiplexing interval
add /proc/sys/kernel/perf_event_mux_interval_ms
entry to adjust the multiplexing period.
Unit is milliseconds.
Signed-off-by: Stephane Eranian <eranian@...gle.com>
---
include/linux/perf_event.h | 5 +++++
kernel/events/core.c | 43 ++++++++++++++++++++++++++++++++++++-------
kernel/sysctl.c | 8 ++++++++
3 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index cc5e2cd..21c3bb0 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1297,11 +1297,16 @@ static inline void perf_callchain_store(struct perf_callchain_entry *entry, u64
extern int sysctl_perf_event_paranoid;
extern int sysctl_perf_event_mlock;
extern int sysctl_perf_event_sample_rate;
+extern int sysctl_perf_event_mux_interval_ms;
extern int perf_proc_update_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp,
loff_t *ppos);
+extern int perf_proc_mux_interval_ms_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos);
+
static inline bool perf_paranoid_tracepoint_raw(void)
{
return sysctl_perf_event_paranoid > -1;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ab4ef10..fd53509 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -144,6 +144,13 @@ static atomic_t nr_mmap_events __read_mostly;
static atomic_t nr_comm_events __read_mostly;
static atomic_t nr_task_events __read_mostly;
+/*
+ * set default to be dependent on timer tick just
+ * like original code
+ */
+#define DEFAULT_MUX_INTERVAL_MS (1000 / HZ)
+static ktime_t perf_cpu_hrtimer_interval; /* mux interval in ktime_t */
+
static LIST_HEAD(pmus);
static DEFINE_MUTEX(pmus_lock);
static struct srcu_struct pmus_srcu;
@@ -174,6 +181,10 @@ int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free'
*/
#define DEFAULT_MAX_SAMPLE_RATE 100000
int sysctl_perf_event_sample_rate __read_mostly = DEFAULT_MAX_SAMPLE_RATE;
+int sysctl_perf_event_mux_interval_ms __read_mostly = DEFAULT_MUX_INTERVAL_MS;
+
+static DEFINE_PER_CPU(struct list_head, rotation_list);
+
static int max_samples_per_tick __read_mostly =
DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ);
@@ -193,6 +204,25 @@ int perf_proc_update_handler(struct ctl_table *table, int write,
return 0;
}
+int perf_proc_mux_interval_ms_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp,
+ loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_dointvec(table, write, buffer, lenp, ppos);
+ if (ret || !write)
+ return ret;
+
+ if (sysctl_perf_event_mux_interval_ms < 1)
+ return -EINVAL;
+
+ perf_cpu_hrtimer_interval =
+ ns_to_ktime(sysctl_perf_event_mux_interval_ms * NSEC_PER_MSEC);
+
+ return 0;
+}
+
static atomic64_t perf_event_id;
static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
@@ -636,11 +666,6 @@ perf_cgroup_mark_enabled(struct perf_event *event,
}
#endif
-/*
- * set default to be dependent on timer tick just
- * like original code
- */
-#define PERF_CPU_HRTIMER (1000 / HZ)
static enum hrtimer_restart perf_cpu_hrtimer_handler(struct hrtimer *hr)
{
struct perf_cpu_hrtimer *h = &__get_cpu_var(perf_cpu_hrtimer);
@@ -673,7 +698,7 @@ static enum hrtimer_restart perf_cpu_hrtimer_handler(struct hrtimer *hr)
* arm timer if needed
*/
if (rotations) {
- hrtimer_forward_now(hr, ns_to_ktime(PERF_CPU_HRTIMER));
+ hrtimer_forward_now(hr, perf_cpu_hrtimer_interval);
ret = HRTIMER_RESTART;
}
end:
@@ -721,7 +746,7 @@ static void perf_cpu_hrtimer_restart(void)
h->active = 1;
if (!hrtimer_callback_running(hr))
- __hrtimer_start_range_ns(hr, ns_to_ktime(PERF_CPU_HRTIMER),
+ __hrtimer_start_range_ns(hr, perf_cpu_hrtimer_interval,
0, HRTIMER_MODE_REL_PINNED, 0);
}
@@ -7517,6 +7542,10 @@ void __init perf_event_init(void)
/* do not patch jump label more than once per second */
jump_label_rate_limit(&perf_sched_events, HZ);
+ /* default multiplexing interval */
+ perf_cpu_hrtimer_interval =
+ ns_to_ktime(DEFAULT_MUX_INTERVAL_MS * NSEC_PER_MSEC);
+
/*
* Build time assertion that we keep the data_head at the intended
* location. IOW, validation we got the __reserved[] size right.
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 81c7b1a..0d7b2c8 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -981,6 +981,14 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = perf_proc_update_handler,
},
+ {
+ .procname = "perf_event_mux_interval_ms",
+ .data = &sysctl_perf_event_mux_interval_ms,
+ .maxlen = sizeof(sysctl_perf_event_mux_interval_ms),
+ .mode = 0644,
+ .proc_handler = perf_proc_mux_interval_ms_handler,
+ },
+
#endif
#ifdef CONFIG_KMEMCHECK
{
--
1.7.5.4
--
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