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-rw-r--r--lib/tools/doc/src/fprof.xml10
1 files changed, 8 insertions, 2 deletions
diff --git a/lib/tools/doc/src/fprof.xml b/lib/tools/doc/src/fprof.xml
index 4c9e48045e..72624bd33b 100644
--- a/lib/tools/doc/src/fprof.xml
+++ b/lib/tools/doc/src/fprof.xml
@@ -328,10 +328,16 @@
purposes. This option is only
allowed with the <c>start</c> option.</item>
<tag><c>cpu_time</c>| <c>{cpu_time, bool()}</c></tag>
- <item>The options <c>cpu_time</c> or <c>{cpu_time, true></c>
+ <item>The options <c>cpu_time</c> or <c>{cpu_time, true}</c>
makes the timestamps in the trace be in CPU time instead
of wallclock time which is the default. This option is
- only allowed with the <c>start</c> option.</item>
+ only allowed with the <c>start</c> option.
+ <warning><p>Getting correct values out of cpu_time can be difficult.
+ The best way to get correct values is to run using a single
+ scheduler and bind that scheduler to a specific CPU,
+ i.e. <c>erl +S 1 +sbt db</c>.</p>
+ </warning>
+ </item>
<tag><c>{procs, PidSpec}</c>| <c>{procs, [PidSpec]}</c></tag>
<item>Specifies which processes that shall be traced. If
this option is not given, the calling process is