diff mbox series

[1/3] block/diskstats: accumulate all per-cpu counters in one pass

Message ID 155413438394.3201.15211440151043943989.stgit@buzz (mailing list archive)
State New, archived
Headers show
Series [1/3] block/diskstats: accumulate all per-cpu counters in one pass | expand

Commit Message

Konstantin Khlebnikov April 1, 2019, 3:59 p.m. UTC 
This is faster and makes code much smaller:

./scripts/bloat-o-meter vmlinux.before vmlinux.after
add/remove: 1/0 grow/shrink: 0/2 up/down: 176/-1348 (-1172)
Function                                     old     new   delta
part_stat_read_all                             -     176    +176
diskstats_show                              1190     569    -621
part_stat_show                              1064     337    -727
Total: Before=13762189, After=13761017, chg -0.01%

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 block/genhd.c             |   62 +++++++++++++++++++++++++++++++++++----------
 block/partition-generic.c |   31 ++++++++++++-----------
 include/linux/genhd.h     |    5 +---
 3 files changed, 67 insertions(+), 31 deletions(-)
diff mbox series

Patch

diff --git a/block/genhd.c b/block/genhd.c
index 703267865f14..2f986af81ba1 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -45,6 +45,34 @@  static void disk_add_events(struct gendisk *disk);
 static void disk_del_events(struct gendisk *disk);
 static void disk_release_events(struct gendisk *disk);
 
+#ifdef CONFIG_SMP
+void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
+{
+	int cpu;
+
+	memset(stat, 0, sizeof(struct disk_stats));
+	for_each_possible_cpu(cpu) {
+		struct disk_stats *ptr = per_cpu_ptr(part->dkstats, cpu);
+		int group;
+
+		for (group = 0; group < NR_STAT_GROUPS; group++) {
+			stat->nsecs[group] += ptr->nsecs[group];
+			stat->sectors[group] += ptr->sectors[group];
+			stat->ios[group] += ptr->ios[group];
+			stat->merges[group] += ptr->merges[group];
+		}
+
+		stat->io_ticks += ptr->io_ticks;
+		stat->time_in_queue += ptr->time_in_queue;
+	}
+}
+#else /* CONFIG_SMP */
+void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
+{
+	memcpy(stat, &part->dkstats, sizeof(struct disk_stats));
+}
+#endif /* CONFIG_SMP */
+
 void part_inc_in_flight(struct request_queue *q, struct hd_struct *part, int rw)
 {
 	if (queue_is_mq(q))
@@ -1341,6 +1369,7 @@  static int diskstats_show(struct seq_file *seqf, void *v)
 	struct hd_struct *hd;
 	char buf[BDEVNAME_SIZE];
 	unsigned int inflight;
+	struct disk_stats stat;
 
 	/*
 	if (&disk_to_dev(gp)->kobj.entry == block_class.devices.next)
@@ -1352,7 +1381,9 @@  static int diskstats_show(struct seq_file *seqf, void *v)
 
 	disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
 	while ((hd = disk_part_iter_next(&piter))) {
+		part_stat_read_all(hd, &stat);
 		inflight = part_in_flight(gp->queue, hd);
+
 		seq_printf(seqf, "%4d %7d %s "
 			   "%lu %lu %lu %u "
 			   "%lu %lu %lu %u "
@@ -1360,21 +1391,24 @@  static int diskstats_show(struct seq_file *seqf, void *v)
 			   "%lu %lu %lu %u\n",
 			   MAJOR(part_devt(hd)), MINOR(part_devt(hd)),
 			   disk_name(gp, hd->partno, buf),
-			   part_stat_read(hd, ios[STAT_READ]),
-			   part_stat_read(hd, merges[STAT_READ]),
-			   part_stat_read(hd, sectors[STAT_READ]),
-			   (unsigned int)part_stat_read_msecs(hd, STAT_READ),
-			   part_stat_read(hd, ios[STAT_WRITE]),
-			   part_stat_read(hd, merges[STAT_WRITE]),
-			   part_stat_read(hd, sectors[STAT_WRITE]),
-			   (unsigned int)part_stat_read_msecs(hd, STAT_WRITE),
+			   stat.ios[STAT_READ],
+			   stat.merges[STAT_READ],
+			   stat.sectors[STAT_READ],
+			   (unsigned int)div_u64(stat.nsecs[STAT_READ],
+							NSEC_PER_MSEC),
+			   stat.ios[STAT_WRITE],
+			   stat.merges[STAT_WRITE],
+			   stat.sectors[STAT_WRITE],
+			   (unsigned int)div_u64(stat.nsecs[STAT_WRITE],
+							NSEC_PER_MSEC),
 			   inflight,
-			   jiffies_to_msecs(part_stat_read(hd, io_ticks)),
-			   jiffies_to_msecs(part_stat_read(hd, time_in_queue)),
-			   part_stat_read(hd, ios[STAT_DISCARD]),
-			   part_stat_read(hd, merges[STAT_DISCARD]),
-			   part_stat_read(hd, sectors[STAT_DISCARD]),
-			   (unsigned int)part_stat_read_msecs(hd, STAT_DISCARD)
+			   jiffies_to_msecs(stat.io_ticks),
+			   jiffies_to_msecs(stat.time_in_queue),
+			   stat.ios[STAT_DISCARD],
+			   stat.merges[STAT_DISCARD],
+			   stat.sectors[STAT_DISCARD],
+			   (unsigned int)div_u64(stat.nsecs[STAT_DISCARD],
+							NSEC_PER_MSEC)
 			);
 	}
 	disk_part_iter_exit(&piter);
diff --git a/block/partition-generic.c b/block/partition-generic.c
index 8e596a8dff32..621e0d9f3c92 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -120,30 +120,33 @@  ssize_t part_stat_show(struct device *dev,
 {
 	struct hd_struct *p = dev_to_part(dev);
 	struct request_queue *q = part_to_disk(p)->queue;
+	struct disk_stats stat;
 	unsigned int inflight;
 
+	part_stat_read_all(p, &stat);
 	inflight = part_in_flight(q, p);
+
 	return sprintf(buf,
 		"%8lu %8lu %8llu %8u "
 		"%8lu %8lu %8llu %8u "
 		"%8u %8u %8u "
 		"%8lu %8lu %8llu %8u"
 		"\n",
-		part_stat_read(p, ios[STAT_READ]),
-		part_stat_read(p, merges[STAT_READ]),
-		(unsigned long long)part_stat_read(p, sectors[STAT_READ]),
-		(unsigned int)part_stat_read_msecs(p, STAT_READ),
-		part_stat_read(p, ios[STAT_WRITE]),
-		part_stat_read(p, merges[STAT_WRITE]),
-		(unsigned long long)part_stat_read(p, sectors[STAT_WRITE]),
-		(unsigned int)part_stat_read_msecs(p, STAT_WRITE),
+		stat.ios[STAT_READ],
+		stat.merges[STAT_READ],
+		(unsigned long long)stat.sectors[STAT_READ],
+		(unsigned int)div_u64(stat.nsecs[STAT_READ], NSEC_PER_MSEC),
+		stat.ios[STAT_WRITE],
+		stat.merges[STAT_WRITE],
+		(unsigned long long)stat.sectors[STAT_WRITE],
+		(unsigned int)div_u64(stat.nsecs[STAT_WRITE], NSEC_PER_MSEC),
 		inflight,
-		jiffies_to_msecs(part_stat_read(p, io_ticks)),
-		jiffies_to_msecs(part_stat_read(p, time_in_queue)),
-		part_stat_read(p, ios[STAT_DISCARD]),
-		part_stat_read(p, merges[STAT_DISCARD]),
-		(unsigned long long)part_stat_read(p, sectors[STAT_DISCARD]),
-		(unsigned int)part_stat_read_msecs(p, STAT_DISCARD));
+		jiffies_to_msecs(stat.io_ticks),
+		jiffies_to_msecs(stat.time_in_queue),
+		stat.ios[STAT_DISCARD],
+		stat.merges[STAT_DISCARD],
+		(unsigned long long)stat.sectors[STAT_DISCARD],
+		(unsigned int)div_u64(stat.nsecs[STAT_DISCARD], NSEC_PER_MSEC));
 }
 
 ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 06c0fd594097..7f981be190b4 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -357,9 +357,6 @@  static inline void free_part_stats(struct hd_struct *part)
 
 #endif /* CONFIG_SMP */
 
-#define part_stat_read_msecs(part, which)				\
-	div_u64(part_stat_read(part, nsecs[which]), NSEC_PER_MSEC)
-
 #define part_stat_read_accum(part, field)				\
 	(part_stat_read(part, field[STAT_READ]) +			\
 	 part_stat_read(part, field[STAT_WRITE]) +			\
@@ -391,6 +388,8 @@  static inline void free_part_stats(struct hd_struct *part)
 #define part_stat_local_read_cpu(gendiskp, field, cpu)			\
 	local_read(&(part_stat_get_cpu(gendiskp, field, cpu)))
 
+void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat);
+
 unsigned int part_in_flight(struct request_queue *q, struct hd_struct *part);
 void part_in_flight_rw(struct request_queue *q, struct hd_struct *part,
 		       unsigned int inflight[2]);