Re: [PATCH 1/2] perf tools: add event modifier to request exclusive PMU access

[Jiri Olsa <jolsa@redhat.com>]

On Fri, Oct 19, 2012 at 05:47:11PM +0200, Stephane Eranian wrote:
> On Fri, Oct 19, 2012 at 5:23 PM, Jiri Olsa <jolsa@redhat.com> wrote:
> > On Fri, Oct 19, 2012 at 05:17:57PM +0200, Stephane Eranian wrote:
> >> On Fri, Oct 19, 2012 at 5:13 PM, Peter Zijlstra <peterz@infradead.org> wrote:
> >> > On Fri, 2012-10-19 at 16:52 +0200, Stephane Eranian wrote:
> >> >> -modifier_event [ukhpGH]{1,8}
> >> >> +modifier_event [ukhpGHx]{1,8}
> >> >
> >> > wouldn't the max modifier sting length grow by adding another possible
> >> > modifier?
> >>
> >> That's what I thought too, but then I don't understand why it was at
> >> eight before and not
> >> seven: One instance of each letter, + a second for pp (precise=2). Or
> >> am I missing
> >> something here?
> >
> > hm, I think I assumed for some reason that 'ppp' is valid as well
> >
> If that's the case, then yes, I need to bump that number to 9.

found my source ;)

include/linux/perf_event.h:
...

           /*
            * precise_ip:
            *
            *  0 - SAMPLE_IP can have arbitrary skid
            *  1 - SAMPLE_IP must have constant skid
            *  2 - SAMPLE_IP requested to have 0 skid
            *  3 - SAMPLE_IP must have 0 skid
            *
            *  See also PERF_RECORD_MISC_EXACT_IP
            */
           precise_ip     :  2, /* skid constraint       */
...


jirka