Recent changes (master)

[Jens Axboe <axboe@kernel.dk>]

The following changes since commit 2b00ac1c82d54795911343c9b3b3f4ef64c92d92:

  Merge branch 'fix-parse-sync-file-range' of https://github.com/oleglatin/fio (2021-11-24 10:27:20 -0700)

are available in the Git repository at:

  git://git.kernel.dk/fio.git master

for you to fetch changes up to ed7f3a07363d62c6d6147b0c568f87f079d241a8:

  stat: make add lat percentile functions inline (2021-11-25 09:03:10 -0700)

----------------------------------------------------------------
Niklas Cassel (6):
      docs: document quirky implementation of per priority stats reporting
      stat: add comments describing the quirky behavior of clat prio samples
      stat: rename add_lat_percentile_sample()
      stat: rename add_lat_percentile_sample_noprio()
      stat: simplify add_lat_percentile_prio_sample()
      stat: make add lat percentile functions inline

 HOWTO  |  6 +++++-
 fio.1  |  5 ++++-
 stat.c | 52 +++++++++++++++++++++++++++++++++++++++-------------
 3 files changed, 48 insertions(+), 15 deletions(-)

---

Diff of recent changes:

diff --git a/HOWTO b/HOWTO
index a3b3acfe..8c9e4135 100644
--- a/HOWTO
+++ b/HOWTO
@@ -2169,7 +2169,11 @@ with the caveat that when used on the command line, they must come after the
     Default: 0. A single value applies to reads and writes. Comma-separated
     values may be specified for reads and writes. For this option to be
     effective, NCQ priority must be supported and enabled, and `direct=1'
-    option must be used. fio must also be run as the root user.
+    option must be used. fio must also be run as the root user. Unlike
+    slat/clat/lat stats, which can be tracked and reported independently, per
+    priority stats only track and report a single type of latency. By default,
+    completion latency (clat) will be reported, if :option:`lat_percentiles` is
+    set, total latency (lat) will be reported.
 
 .. option:: cmdprio_class=int[,int] : [io_uring] [libaio]
 
diff --git a/fio.1 b/fio.1
index a6469541..a3ebb67d 100644
--- a/fio.1
+++ b/fio.1
@@ -1967,7 +1967,10 @@ Set the percentage of I/O that will be issued with the highest priority.
 Default: 0. A single value applies to reads and writes. Comma-separated
 values may be specified for reads and writes. For this option to be effective,
 NCQ priority must be supported and enabled, and `direct=1' option must be
-used. fio must also be run as the root user.
+used. fio must also be run as the root user. Unlike slat/clat/lat stats, which
+can be tracked and reported independently, per priority stats only track and
+report a single type of latency. By default, completion latency (clat) will be
+reported, if \fBlat_percentiles\fR is set, total latency (lat) will be reported.
 .TP
 .BI (io_uring,libaio)cmdprio_class \fR=\fPint[,int]
 Set the I/O priority class to use for I/Os that must be issued with a
diff --git a/stat.c b/stat.c
index e0dc99b6..7e84058d 100644
--- a/stat.c
+++ b/stat.c
@@ -3052,8 +3052,10 @@ void add_sync_clat_sample(struct thread_stat *ts, unsigned long long nsec)
 	add_stat_sample(&ts->sync_stat, nsec);
 }
 
-static void add_lat_percentile_sample_noprio(struct thread_stat *ts,
-				unsigned long long nsec, enum fio_ddir ddir, enum fio_lat lat)
+static inline void add_lat_percentile_sample(struct thread_stat *ts,
+					     unsigned long long nsec,
+					     enum fio_ddir ddir,
+					     enum fio_lat lat)
 {
 	unsigned int idx = plat_val_to_idx(nsec);
 	assert(idx < FIO_IO_U_PLAT_NR);
@@ -3061,14 +3063,13 @@ static void add_lat_percentile_sample_noprio(struct thread_stat *ts,
 	ts->io_u_plat[lat][ddir][idx]++;
 }
 
-static void add_lat_percentile_sample(struct thread_stat *ts,
-				unsigned long long nsec, enum fio_ddir ddir,
-				bool high_prio, enum fio_lat lat)
+static inline void add_lat_percentile_prio_sample(struct thread_stat *ts,
+						  unsigned long long nsec,
+						  enum fio_ddir ddir,
+						  bool high_prio)
 {
 	unsigned int idx = plat_val_to_idx(nsec);
 
-	add_lat_percentile_sample_noprio(ts, nsec, ddir, lat);
-
 	if (!high_prio)
 		ts->io_u_plat_low_prio[ddir][idx]++;
 	else
@@ -3089,6 +3090,15 @@ void add_clat_sample(struct thread_data *td, enum fio_ddir ddir,
 
 	add_stat_sample(&ts->clat_stat[ddir], nsec);
 
+	/*
+	 * When lat_percentiles=1 (default 0), the reported high/low priority
+	 * percentiles and stats are used for describing total latency values,
+	 * even though the variable names themselves start with clat_.
+	 *
+	 * Because of the above definition, add a prio stat sample only when
+	 * lat_percentiles=0. add_lat_sample() will add the prio stat sample
+	 * when lat_percentiles=1.
+	 */
 	if (!ts->lat_percentiles) {
 		if (high_prio)
 			add_stat_sample(&ts->clat_high_prio_stat[ddir], nsec);
@@ -3101,10 +3111,15 @@ void add_clat_sample(struct thread_data *td, enum fio_ddir ddir,
 			       offset, ioprio);
 
 	if (ts->clat_percentiles) {
-		if (ts->lat_percentiles)
-			add_lat_percentile_sample_noprio(ts, nsec, ddir, FIO_CLAT);
-		else
-			add_lat_percentile_sample(ts, nsec, ddir, high_prio, FIO_CLAT);
+		/*
+		 * Because of the above definition, add a prio lat percentile
+		 * sample only when lat_percentiles=0. add_lat_sample() will add
+		 * the prio lat percentile sample when lat_percentiles=1.
+		 */
+		add_lat_percentile_sample(ts, nsec, ddir, FIO_CLAT);
+		if (!ts->lat_percentiles)
+			add_lat_percentile_prio_sample(ts, nsec, ddir,
+						       high_prio);
 	}
 
 	if (iolog && iolog->hist_msec) {
@@ -3169,7 +3184,7 @@ void add_slat_sample(struct thread_data *td, enum fio_ddir ddir,
 			       offset, ioprio);
 
 	if (ts->slat_percentiles)
-		add_lat_percentile_sample_noprio(ts, nsec, ddir, FIO_SLAT);
+		add_lat_percentile_sample(ts, nsec, ddir, FIO_SLAT);
 
 	if (needs_lock)
 		__td_io_u_unlock(td);
@@ -3194,8 +3209,19 @@ void add_lat_sample(struct thread_data *td, enum fio_ddir ddir,
 		add_log_sample(td, td->lat_log, sample_val(nsec), ddir, bs,
 			       offset, ioprio);
 
+	/*
+	 * When lat_percentiles=1 (default 0), the reported high/low priority
+	 * percentiles and stats are used for describing total latency values,
+	 * even though the variable names themselves start with clat_.
+	 *
+	 * Because of the above definition, add a prio stat and prio lat
+	 * percentile sample only when lat_percentiles=1. add_clat_sample() will
+	 * add the prio stat and prio lat percentile sample when
+	 * lat_percentiles=0.
+	 */
 	if (ts->lat_percentiles) {
-		add_lat_percentile_sample(ts, nsec, ddir, high_prio, FIO_LAT);
+		add_lat_percentile_sample(ts, nsec, ddir, FIO_LAT);
+		add_lat_percentile_prio_sample(ts, nsec, ddir, high_prio);
 		if (high_prio)
 			add_stat_sample(&ts->clat_high_prio_stat[ddir], nsec);
 		else