GNU bug report logs - #18522
occasional slow performance in some Gnus code

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Message #132 received at 18522 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Peter Münster <pmlists <at> free.fr>
Cc: rudalics <at> gmx.at, larsi <at> gnus.org, 18522 <at> debbugs.gnu.org
Subject: Re: bug#18522: 24.4.50; mapcar is very slow
Date: Mon, 22 Feb 2016 22:56:43 +0200

> From: Peter Münster <pmlists <at> free.fr>
> Cc: rudalics <at> gmx.at,  larsi <at> gnus.org,  18522 <at> debbugs.gnu.org
> Date: Mon, 22 Feb 2016 21:41:11 +0100
> 
> On Mon, Feb 22 2016, Eli Zaretskii wrote:
> 
> > I think the next step is to profile the code below "let".  Can you try
> > using 'perf' for that purpose?
> 
> Slow emacs: almost all time is spent in Fset_default (96%)
> 
> Fast emacs:
>   25.36%  emacs         emacs                          [.] eval_sub
>   10.73%  emacs         emacs                          [.] Fset_default
>    9.63%  emacs         emacs                          [.] Flength
>    6.54%  emacs         emacs                          [.] unbind_to
>    5.44%  emacs         emacs                          [.] hash_lookup
>    4.53%  emacs         emacs                          [.] Flet

So now the question becomes: which part of Fset_default?  I thought it
was the loop over all the buffers, but your session seems to say it
couldn't be.  Then what is it?

> You can try it too on your running sessions: "perf record -p PID" and
> then "perf report". (just use something like "dotimes (i 1000000000)")

Alas, there's no 'perf' on MS-Windows (nor anything like it, AFAIK).

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