man: update description of normal output latencies

1) Describe lat (min, max, avg, stddev) line
2) Use IO latencies description for lat (nsec/usec/msec) lines
3) Fix IO latency description

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fio.1 b/fio.1
index 74eae8ab33a301d3f30a2f801a5b852b0e20a4ec..31d0a3b22b91c54a41ccf4f44213a717c6266abd 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -2793,9 +2793,9 @@ group) the output looks like:
                     | 99.99th=[78119]
                   bw (  KiB/s): min=  532, max=  686, per=0.10%, avg=622.87, stdev=24.82, samples=  100
                   iops        : min=   76, max=   98, avg=88.98, stdev= 3.54, samples=  100
                     | 99.99th=[78119]
                   bw (  KiB/s): min=  532, max=  686, per=0.10%, avg=622.87, stdev=24.82, samples=  100
                   iops        : min=   76, max=   98, avg=88.98, stdev= 3.54, samples=  100

-                   lat (usec) : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
-                   lat (msec) : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
-                   lat (msec) : 100=0.65%
+                 lat (usec)   : 250=0.04%, 500=64.11%, 750=4.81%, 1000=2.79%
+                 lat (msec)   : 2=4.16%, 4=1.84%, 10=4.90%, 20=11.33%, 50=5.37%
+                 lat (msec)   : 100=0.65%

                  cpu          : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
                  IO depths    : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
                     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
                  cpu          : usr=0.27%, sys=0.18%, ctx=12072, majf=0, minf=21
                  IO depths    : 1=85.0%, 2=13.1%, 4=1.8%, 8=0.1%, 16=0.0%, 32=0.0%, >=64=0.0%
                     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%


@@ -2836,6 +2836,10 @@ usually be equal (or very close) to 0, as the time from submit to
 complete is basically just CPU time (I/O has already been done, see slat
 explanation).
 .TP
 complete is basically just CPU time (I/O has already been done, see slat
 explanation).
 .TP

+.B lat
+Total latency. Same names as slat and clat, this denotes the time from
+when fio created the I/O unit to completion of the I/O operation.
+.TP

 .B bw
 Bandwidth statistics based on samples. Same names as the xlat stats,
 but also includes the number of samples taken (\fIsamples\fR) and an
 .B bw
 Bandwidth statistics based on samples. Same names as the xlat stats,
 but also includes the number of samples taken (\fIsamples\fR) and an


@@ -2847,6 +2851,14 @@ are then competing for disk access.
 .B iops
 IOPS statistics based on samples. Same names as \fBbw\fR.
 .TP
 .B iops
 IOPS statistics based on samples. Same names as \fBbw\fR.
 .TP

+.B lat (nsec/usec/msec)
+The distribution of I/O completion latencies. This is the time from when
+I/O leaves fio and when it gets completed. Unlike the separate
+read/write/trim sections above, the data here and in the remaining
+sections apply to all I/Os for the reporting group. 250=0.04% means that
+0.04% of the I/Os completed in under 250us. 500=64.11% means that 64.11%
+of the I/Os required 250 to 499us for completion.
+.TP

 .B cpu
 CPU usage. User and system time, along with the number of context
 switches this thread went through, usage of system and user time, and
 .B cpu
 CPU usage. User and system time, along with the number of context
 switches this thread went through, usage of system and user time, and


@@ -2877,12 +2889,10 @@ Like the above \fBsubmit\fR number, but for completions instead.
 The number of \fBread/write/trim\fR requests issued, and how many of them were
 short or dropped.
 .TP
 The number of \fBread/write/trim\fR requests issued, and how many of them were
 short or dropped.
 .TP

-.B IO latencies
-The distribution of I/O completion latencies. This is the time from when
-I/O leaves fio and when it gets completed. The numbers follow the same
-pattern as the I/O \fBdepths\fR, meaning that 2=1.6% means that 1.6% of the
-I/O completed within 2 msecs, 20=12.8% means that 12.8% of the I/O took
-more than 10 msecs, but less than (or equal to) 20 msecs.
+.B IO latency
+These values are for \fBlatency-target\fR and related options. When
+these options are engaged, this section describes the I/O depth required
+to meet the specified latency target.

 .RE
 .P
 After each client has been listed, the group statistics are printed. They
 .RE
 .P
 After each client has been listed, the group statistics are printed. They