Manual:$wgDebugFunctionEntry

Profiling: $wgDebugFunctionEntry
Whether to additionally output a debug message on every wfProfileIn() and wfProfileOut() call.
Introduced in version:1.1.0
Removed in version:1.25.0 (Gerrit change 183434; git #6d19ca42)
Allowed values:(boolean)
Default value:false (1.19-1.24)
0 (1.1-1.18)

Details

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Whether to additionally output a debug message on every wfProfileIn() and wfProfileOut() call.

You also need to use a non-stub profiler to get these messages, see Manual:Profiling for more information about this.