Which platforms do/do not support cpu time profiling?

Which platforms do/do not support cpu time profiling?

[Glenn Morris]

etc/NEWS says:

  ** New sampling-based Elisp profiler.
  [...]
  The sampling rate can be based on CPU time (only supported on some
  systems)..


Which are the platforms which do/do not support this?


There is a configure option --enable-profiling which you might think has
something to do with this, but it doesn't. Is that option still useful,
and if so can someone come up with a more informative description for it
than "build emacs with profiling support"?

Re: Which platforms do/do not support cpu time profiling?

[Glenn Morris]

Glenn Morris wrote:

> There is a configure option --enable-profiling which you might think has
> something to do with this, but it doesn't. Is that option still useful,
> and if so can someone come up with a more informative description for it
> than "build emacs with profiling support"?

Apparently they conflict?

http://lists.gnu.org/archive/html/emacs-devel/2012-09/msg00816.html

So configuring with --enable-profiling will actually disable the feature
that is almost certainly just going to be referred to just as
"profiling"? That's rather confusing.

Now we have:
--enable-profiling
profiler.el
elp.el
benchmark.el

all undocumented in any manual.

Re: Which platforms do/do not support cpu time profiling?

[Eli Zaretskii]

> X-Spam-Status: No, score=-6.0 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_HI,
> 	RP_MATCHES_RCVD,UNRESOLVED_TEMPLATE autolearn=unavailable version=3.3.2
> From: Glenn Morris <rgm@gnu.org>
> Date: Mon, 19 Nov 2012 20:25:56 -0500
> 
> 
> etc/NEWS says:
> 
>   ** New sampling-based Elisp profiler.
>   [...]
>   The sampling rate can be based on CPU time (only supported on some
>   systems)..
> 
> 
> Which are the platforms which do/do not support this?

None.  Even MS-DOS supports this.

Re: Which platforms do/do not support cpu time profiling?

[Paul Eggert]

On 11/19/2012 05:25 PM, Glenn Morris wrote:
> Which are the platforms which do/do not support this?

It's pretty universal these days.  BeOS doesn't support it,
but that's the only platform I know offhand.

> There is a configure option --enable-profiling which you might think has
> something to do with this, but it doesn't. Is that option still useful,

Yes.  The terminology clash is unfortunate, but both things are
called "profiling" so we probably should apply an adjective to
the low-level profiling, e.g., "gprof style profiling", at least
in the help string and perhaps in the switch itself.

Re: Which platforms do/do not support cpu time profiling?

[Glenn Morris]

Paul Eggert wrote:

>> There is a configure option --enable-profiling which you might think has
>> something to do with this, but it doesn't. Is that option still useful,
>
> Yes.  The terminology clash is unfortunate, but both things are
> called "profiling" so we probably should apply an adjective to
> the low-level profiling, e.g., "gprof style profiling", at least
> in the help string and perhaps in the switch itself.

Why would I want to configure with --enable-profiling, and if I do, how
do I use it?

Re: Which platforms do/do not support cpu time profiling?

[Paul Eggert]

On 11/20/12 09:00, Glenn Morris wrote:
> Why would I want to configure with --enable-profiling, and if I do, how
> do I use it?

You'd do that if you want a low-level CPU profile, one that
maps instruction counts to C functions (or even to
machine instructions).  You run Emacs and it automatically
generates a file gmon.out when it exits.  You then run
the shell command 'gprof emacs gmon.out' to get a textual summary of the
CPU profile.

It's helpful sometimes, when debugging, to get a profile
at this low level rather than at the Lisp level, which
is what the Emacs profiler does.