Merge tag 'perf-core-for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

 * Fix include order for bison/flex-generated C files, from Ben Hutchings

 * Build fixes and documentation corrections from David Ahern

 * Group parsing support, from Jiri Olsa

 * UI/gtk refactorings and improvements from Namhyung Kim

 * NULL deref fix for perf script, from Namhyung Kim

 * Assorted cleanups from Robert Richter

 * Let O= makes handle relative paths, from Steven Rostedt

 * perf script python fixes, from Feng Tang.

 * Improve 'perf lock' error message when the needed tracepoints
   are not present, from David Ahern.

 * Initial bash completion support, from Frederic Weisbecker

 * Allow building without libelf, from Namhyung Kim.

 * Support DWARF CFI based unwind to have callchains when %bp
   based unwinding is not possible, from Jiri Olsa.

 * Symbol resolution fixes, while fixing support PPC64 files with an .opt ELF
   section was the end goal, several fixes for code that handles all
   architectures and cleanups are included, from Cody Schafer.

 * Add a description for the JIT interface, from Andi Kleen.

 * Assorted fixes for Documentation and build in 32 bit, from Robert Richter

 * Add support for non-tracepoint events in perf script python, from Feng Tang

 * Cache the libtraceevent event_format associated to each evsel early, so that we
   avoid relookups, i.e. calling pevent_find_event repeatedly when processing
   tracepoint events.

   [ This is to reduce the surface contact with libtraceevents and make clear what
     is that the perf tools needs from that lib: so far parsing the common and per
     event fields. ]

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 66 insertions, 42 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 93d8d2f7108..5ad5ce23c1e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -34,6 +34,7 @@
 #include <linux/syscalls.h>
 #include <linux/buffer_head.h> /* __set_page_dirty_buffers */
 #include <linux/pagevec.h>
+#include <linux/timer.h>
 #include <trace/events/writeback.h>
 
 /*
@@ -135,7 +136,20 @@ unsigned long global_dirty_limit;
  * measured in page writeback completions.
  *
  */
-static struct prop_descriptor vm_completions;
+static struct fprop_global writeout_completions;
+
+static void writeout_period(unsigned long t);
+/* Timer for aging of writeout_completions */
+static struct timer_list writeout_period_timer =
+		TIMER_DEFERRED_INITIALIZER(writeout_period, 0, 0);
+static unsigned long writeout_period_time = 0;
+
+/*
+ * Length of period for aging writeout fractions of bdis. This is an
+ * arbitrarily chosen number. The longer the period, the slower fractions will
+ * reflect changes in current writeout rate.
+ */
+#define VM_COMPLETIONS_PERIOD_LEN (3*HZ)
 
 /*
  * Work out the current dirty-memory clamping and background writeout
@@ -322,34 +336,6 @@ bool zone_dirty_ok(struct zone *zone)
 	       zone_page_state(zone, NR_WRITEBACK) <= limit;
 }
 
-/*
- * couple the period to the dirty_ratio:
- *
- *   period/2 ~ roundup_pow_of_two(dirty limit)
- */
-static int calc_period_shift(void)
-{
-	unsigned long dirty_total;
-
-	if (vm_dirty_bytes)
-		dirty_total = vm_dirty_bytes / PAGE_SIZE;
-	else
-		dirty_total = (vm_dirty_ratio * global_dirtyable_memory()) /
-				100;
-	return 2 + ilog2(dirty_total - 1);
-}
-
-/*
- * update the period when the dirty threshold changes.
- */
-static void update_completion_period(void)
-{
-	int shift = calc_period_shift();
-	prop_change_shift(&vm_completions, shift);
-
-	writeback_set_ratelimit();
-}
-
 int dirty_background_ratio_handler(struct ctl_table *table, int write,
 		void __user *buffer, size_t *lenp,
 		loff_t *ppos)
@@ -383,7 +369,7 @@ int dirty_ratio_handler(struct ctl_table *table, int write,
 
 	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 	if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
-		update_completion_period();
+		writeback_set_ratelimit();
 		vm_dirty_bytes = 0;
 	}
 	return ret;
@@ -398,12 +384,21 @@ int dirty_bytes_handler(struct ctl_table *table, int write,
 
 	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 	if (ret == 0 && write && vm_dirty_bytes != old_bytes) {
-		update_completion_period();
+		writeback_set_ratelimit();
 		vm_dirty_ratio = 0;
 	}
 	return ret;
 }
 
+static unsigned long wp_next_time(unsigned long cur_time)
+{
+	cur_time += VM_COMPLETIONS_PERIOD_LEN;
+	/* 0 has a special meaning... */
+	if (!cur_time)
+		return 1;
+	return cur_time;
+}
+
 /*
  * Increment the BDI's writeout completion count and the global writeout
  * completion count. Called from test_clear_page_writeback().
@@ -411,8 +406,19 @@ int dirty_bytes_handler(struct ctl_table *table, int write,
 static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
 {
 	__inc_bdi_stat(bdi, BDI_WRITTEN);
-	__prop_inc_percpu_max(&vm_completions, &bdi->completions,
-			      bdi->max_prop_frac);
+	__fprop_inc_percpu_max(&writeout_completions, &bdi->completions,
+			       bdi->max_prop_frac);
+	/* First event after period switching was turned off? */
+	if (!unlikely(writeout_period_time)) {
+		/*
+		 * We can race with other __bdi_writeout_inc calls here but
+		 * it does not cause any harm since the resulting time when
+		 * timer will fire and what is in writeout_period_time will be
+		 * roughly the same.
+		 */
+		writeout_period_time = wp_next_time(jiffies);
+		mod_timer(&writeout_period_timer, writeout_period_time);
+	}
 }
 
 void bdi_writeout_inc(struct backing_dev_info *bdi)
@@ -431,11 +437,33 @@ EXPORT_SYMBOL_GPL(bdi_writeout_inc);
 static void bdi_writeout_fraction(struct backing_dev_info *bdi,
 		long *numerator, long *denominator)
 {
-	prop_fraction_percpu(&vm_completions, &bdi->completions,
+	fprop_fraction_percpu(&writeout_completions, &bdi->completions,
 				numerator, denominator);
 }
 
 /*
+ * On idle system, we can be called long after we scheduled because we use
+ * deferred timers so count with missed periods.
+ */
+static void writeout_period(unsigned long t)
+{
+	int miss_periods = (jiffies - writeout_period_time) /
+						 VM_COMPLETIONS_PERIOD_LEN;
+
+	if (fprop_new_period(&writeout_completions, miss_periods + 1)) {
+		writeout_period_time = wp_next_time(writeout_period_time +
+				miss_periods * VM_COMPLETIONS_PERIOD_LEN);
+		mod_timer(&writeout_period_timer, writeout_period_time);
+	} else {
+		/*
+		 * Aging has zeroed all fractions. Stop wasting CPU on period
+		 * updates.
+		 */
+		writeout_period_time = 0;
+	}
+}
+
+/*
  * bdi_min_ratio keeps the sum of the minimum dirty shares of all
  * registered backing devices, which, for obvious reasons, can not
  * exceed 100%.
@@ -475,7 +503,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
 		ret = -EINVAL;
 	} else {
 		bdi->max_ratio = max_ratio;
-		bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100;
+		bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100;
 	}
 	spin_unlock_bh(&bdi_lock);
 
@@ -918,7 +946,7 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
 	 *	bdi->dirty_ratelimit = balanced_dirty_ratelimit;
 	 *
 	 * However to get a more stable dirty_ratelimit, the below elaborated
-	 * code makes use of task_ratelimit to filter out sigular points and
+	 * code makes use of task_ratelimit to filter out singular points and
 	 * limit the step size.
 	 *
 	 * The below code essentially only uses the relative value of
@@ -941,7 +969,7 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
 	 * feel and care are stable dirty rate and small position error.
 	 *
 	 * |task_ratelimit - dirty_ratelimit| is used to limit the step size
-	 * and filter out the sigular points of balanced_dirty_ratelimit. Which
+	 * and filter out the singular points of balanced_dirty_ratelimit. Which
 	 * keeps jumping around randomly and can even leap far away at times
 	 * due to the small 200ms estimation period of dirty_rate (we want to
 	 * keep that period small to reduce time lags).
@@ -1504,7 +1532,6 @@ int dirty_writeback_centisecs_handler(ctl_table *table, int write,
 	void __user *buffer, size_t *length, loff_t *ppos)
 {
 	proc_dointvec(table, write, buffer, length, ppos);
-	bdi_arm_supers_timer();
 	return 0;
 }
 
@@ -1606,13 +1633,10 @@ static struct notifier_block __cpuinitdata ratelimit_nb = {
  */
 void __init page_writeback_init(void)
 {
-	int shift;
-
 	writeback_set_ratelimit();
 	register_cpu_notifier(&ratelimit_nb);
 
-	shift = calc_period_shift();
-	prop_descriptor_init(&vm_completions, shift);
+	fprop_global_init(&writeout_completions);
 }
 
 /**