Re: Elisp native profiler

[Stefan Monnier]

>> > In a nutshell, that thread sleeps until the timer expiration, then
>> > suspends the main thread, calls the SIGPROF handler, resumes the main
>> > thread, and goes back to sleep.  The deviation from the Posix
>> > semantics is that the handler runs in the context of a thread other
>> > than the main thread.
>> Isn't there another difference in that your code samples at a rate
>> determined by the wall-clock time rather than the cpu-time of the process?
> The timer thread is part of the process, so whenever it runs, the
> process runs.
> Or maybe I don't understand what you mean, exactly.

If your profiler is set to sample every 10ms and your Emacs process uses
50% of the CPU, how many samples will you get after 1s: 100 or 50?
And if Emacs is idle waiting for user input, after 1s will you get 100
samples or 0?
Under GNU/Linux (at least with the "old" setitimer code) you'd have
gotten 50 and 0 respectively.


        Stefan