Re: Elisp native profiler

[Eli Zaretskii]

> Date: Mon, 01 Oct 2012 19:52:39 +0200
> From: Eli Zaretskii <address@hidden>
> Cc: address@hidden, address@hidden, address@hidden
> 
> > It's quite worrisome that a simple counting operation, done every 15 ms,
> > should nearly peg a core.  Something seems amiss.
> 
> I think this is because with the minimal sampling period I allow, the
> timer thread almost never sleeps, and I think the signal handler does
> quite a lot.

Actually, I take this back: I'm quite sure the problem is that the
handler is quite expensive.  The proof: when the user types 
"M-x profiler-stop RET", the timer thread does not exit, it continues
to run, sleeping 30 ms at a time, then awakens, sees that the timer is
disabled, and goes back to sleep.  So almost the whole thread loop is
executed, except suspending/resuming the main thread and calling the
handler.  The difference in terms of CPU usage is tremendous, though:
zero CPU usage.

So either suspending/resuming a thread takes a lot of time, or the
handler, or both.