GNU bug report logs - #76609
31.0.50; The 0.1s repeat timer is very CPU-intensive; it might be a bug?

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From: Eval Exec <execvy <at> gmail.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 76609 <at> debbugs.gnu.org
Subject: bug#76609: 31.0.50; The 0.1s repeat timer is very CPU-intensive;  it might be a bug?
Date: Thu, 27 Feb 2025 22:34:44 +0800

45% CPU for a 0.1s repeating timer does seem surprisingly high. Is
there a way we can optimize this, given the frequent timer
invocations?

On Thu, Feb 27, 2025 at 10:27 PM Eli Zaretskii <eliz <at> gnu.org> wrote:
>
> > From: Eval Exec <execvy <at> gmail.com>
> > Date: Thu, 27 Feb 2025 21:55:40 +0800
> >
> > I a 0.1 s repeat timer in emacs -Q, then Emacs's the cpu usage is 30% ~
> > 70%.
> > I think it's a bug.
>
> I get around 45% with this, but why do you consider this a bug?  Your
> timer function perhaps does nothing, but the timer machinery is
> invoked every 100 msec, and it does consume CPU.
>
> in addition, when you have a high-frequency timer, the Emacs idle loop
> is much more expensive, because instead of waiting inside pselect, it
> runs all the loop code every 100 msec.
>
> Maybe I'm missing something, but I don't see a bug here.

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