cvs commit: src/sys/libkern mcount.c

[Kip Macy]

- Original message -
No. It's unlikely that you even configure profiling.  Bruce


ROTFL. In that case what does 'config -pp' do? And why did it print
something to the effect of "profiling configured" on the console? And
why did the hang go away when I re-built without '-pp'?

Never mind. I'll just take the time to update the hwpmc support for my
hardware. "hwpmc" also doesn't cause a 50% slowdown when in use.


                 -Kip


On 6/13/07, Bruce Evans <brde at optusnet.com.au> wrote:
> On Tue, 12 Jun 2007, Kip Macy wrote:
>
> > On 6/12/07, Bruce Evans <bde at freebsd.org> wrote:
> >> bde         2007-06-13 06:17:48 UTC
> >>
> >>   FreeBSD src repository
> >>
> >>   Modified files:
> >>     sys/libkern          mcount.c
> >>   Log:
> >>   Unbreak high resolution profiling a little: use dummy asms to prevent
> >>   timing loops being optimized away.
> >>
> >>   Once apon a time, gcc promised not to optimize away timing loops, but
> >>   gcc started optimizing away the call to a null function in the timing
> >>   loop here some time between gcc-3.3.3 and gcc-3.4.6, and it started
> >>   optimizing away the timing loop itself some time between gcc-3.4.6
> >>   and gcc-4.2.
> >
> > Will this fix the hang on boot that I saw earlier today?
>
> No.  It's unlikely that you even configure profiling.
>
> Bruce
>