From f6f80750f75810bdaf56dd9362982055de1d7232 Mon Sep 17 00:00:00 2001 From: Vincent Fu Date: Wed, 10 May 2023 20:10:56 -0400 Subject: [PATCH] docs: expand description for interval-based bw and iops statistics Update HOWTO.rst and fio.1 to provide more details about the descriptive statistics interval-based bw and iops measurements. Signed-off-by: Vincent Fu --- HOWTO.rst | 22 +++++++++++++++------- fio.1 | 19 ++++++++++++------- 2 files changed, 27 insertions(+), 14 deletions(-) diff --git a/HOWTO.rst b/HOWTO.rst index 0a6e60c7..80c08f7e 100644 --- a/HOWTO.rst +++ b/HOWTO.rst @@ -4417,15 +4417,23 @@ writes in the example above). In the order listed, they denote: It is the sum of submission and completion latency. **bw** - Bandwidth statistics based on samples. Same names as the xlat stats, - but also includes the number of samples taken (**samples**) and an - approximate percentage of total aggregate bandwidth this thread - received in its group (**per**). This last value is only really - useful if the threads in this group are on the same disk, since they - are then competing for disk access. + Bandwidth statistics based on measurements from discrete + intervals. Fio continuously monitors bytes transferred and I/O + operations completed. By default fio calculates bandwidth in + each half-second interval (see :option:`bwavgtime`) and reports + descriptive statistics for the measurements here. Same names as + the xlat stats, but also includes the number of samples taken + (**samples**) and an approximate percentage of total aggregate + bandwidth this thread received in its group (**per**). This + last value is only really useful if the threads in this group + are on the same disk, since they are then competing for disk + access. **iops** - IOPS statistics based on samples. Same names as bw. + IOPS statistics based on measurements from discrete intervals. + For details see the description for bw above. See + :option:`iopsavgtime` to control the duration of the intervals. + Same values reported here as for bw except for percentage. **lat (nsec/usec/msec)** The distribution of I/O completion latencies. This is the time from when diff --git a/fio.1 b/fio.1 index 4207814b..e577e2e0 100644 --- a/fio.1 +++ b/fio.1 @@ -4073,15 +4073,20 @@ 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 -approximate percentage of total aggregate bandwidth this thread -received in its group (\fIper\fR). This last value is only really -useful if the threads in this group are on the same disk, since they -are then competing for disk access. +Bandwidth statistics based on measurements from discrete intervals. Fio +continuosly monitors bytes transferred and I/O operations completed. By default +fio calculates bandwidth in each half-second interval (see \fBbwavgtime\fR) +and reports descriptive statistics for the measurements here. Same names as the +xlat stats, but also includes the number of samples taken (\fIsamples\fR) and an +approximate percentage of total aggregate bandwidth this thread received in its +group (\fIper\fR). This last value is only really useful if the threads in this +group are on the same disk, since they are then competing for disk access. .TP .B iops -IOPS statistics based on samples. Same names as \fBbw\fR. +IOPS statistics based on measurements from discrete intervals. +For details see the description for \fBbw\fR above. See +\fBiopsavgtime\fR to control the duration of the intervals. +Same values reported here as for \fBbw\fR except for percentage. .TP .B lat (nsec/usec/msec) The distribution of I/O completion latencies. This is the time from when -- 2.25.1