On Fri, 30 Sep 2005, Young Koh wrote:
> > > it seems that sigsetjmp() has
> > > relatively large overhead, we could reduce some overhead by not
> > > calling it.
> >
> > How do you measure it? I'm curious myself - I know there's the possibility
> > to
> > use gprof, but I've never used that myself.
>
> i usually use pentium rdtsc(read time stamp counter) to measure the
> timing and latency. (sometimes by instrumenting kernel or sometimes by
> measuring test programs) i ran a test program and measured the
> overhead of sigsetjmp() and setjmp(). it showed sigsetjmp() uses
> around 1350 cycles (which is around 0.45 us in 3.0GHz machine), and
> setjmp() only 21 cycles (< 0.01us). maybe while sigsetjmp() is
> implemented as a system call to cope with signal blocking/unblocking,
> setjmp() is not a system call? (getpid() itself takes more than 1000
> cycles)
Indeed, setjmp() is not a system call. It just saves the registers to the
passed env structure.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [EMAIL PROTECTED]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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