From: Vincent Fu <vincent.fu@xxxxxxx> 1) Describe lat (min, max, avg, stddev) line 2) Use IO latencies description for lat (nsec/usec/msec) lines 3) Fix IO latency description --- fio.1 | 28 +++++++++++++++++++--------- 1 file changed, 19 insertions(+), 9 deletions(-) diff --git a/fio.1 b/fio.1 index 74eae8a..31d0a3b 100644 --- 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 - 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% @@ -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 +.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 @@ -2847,6 +2851,14 @@ are then competing for disk access. .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 @@ -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 -.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 -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
