Commit 3bf09f2d authored by Brendan Gregg's avatar Brendan Gregg

wordwrap fix, and terminology adjustment

parent b0b3f01c
...@@ -5,14 +5,14 @@ offcputime \- Summarize off-CPU time by kernel stack trace. Uses Linux eBPF/bcc. ...@@ -5,14 +5,14 @@ offcputime \- Summarize off-CPU time by kernel stack trace. Uses Linux eBPF/bcc.
.B offcputime [\-h] [\-u] [\-p PID] [\-i INTERVAL] [\-T] [duration] .B offcputime [\-h] [\-u] [\-p PID] [\-i INTERVAL] [\-T] [duration]
.SH DESCRIPTION .SH DESCRIPTION
This program shows kernel stack traces and task names that were blocked and This program shows kernel stack traces and task names that were blocked and
"off-CPU", and the total duration they were blocked: their "off-CPU time". "off-CPU", and the total duration they were not running: their "off-CPU time".
It works by tracing when threads block and when they return to CPU, measuring It works by tracing when threads block and when they return to CPU, measuring
both the time they were blocked and the blocked kernel stack trace and the both the time they were off-CPU and the blocked kernel stack trace and the
task name. This data is summarized in the kernel using an eBPF map, and by task name. This data is summarized in the kernel using an eBPF map, and by
summing the blocked time by unique stack trace and task name. summing the off-CPU time by unique stack trace and task name.
The output summary will help you identify reasons why threads The output summary will help you identify reasons why threads
were blocking, and quantify the time they were blocked. This spans all types were blocking, and quantify the time they were off-CPU. This spans all types
of blocking activity: disk I/O, network I/O, locks, page faults, involuntary of blocking activity: disk I/O, network I/O, locks, page faults, involuntary
context switches, etc. context switches, etc.
...@@ -46,8 +46,7 @@ duration ...@@ -46,8 +46,7 @@ duration
Duration to trace, in seconds. Duration to trace, in seconds.
.SH EXAMPLES .SH EXAMPLES
.TP .TP
Trace all thread blocking events, and summarize (in-kernel) by kernel stack Trace all thread blocking events, and summarize (in-kernel) by kernel stack trace and total off-CPU time:
trace and total off-CPU time:
# #
.B offcputime .B offcputime
.TP .TP
...@@ -55,8 +54,7 @@ Trace for 5 seconds only: ...@@ -55,8 +54,7 @@ Trace for 5 seconds only:
# #
.B offcputime 5 .B offcputime 5
.TP .TP
Trace for 5 seconds, and emit output in folded stack format (suitable for Trace for 5 seconds, and emit output in folded stack format (suitable for flame graphs):
flame graphs):
# #
.B offcputime -f 5 .B offcputime -f 5
.TP .TP
......
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