On Tue, May 10, 2011 at 11:25:14AM -0400, Peter Zijlstra wrote:
> On Tue, 2011-05-10 at 17:08 +0200, Roedel, Joerg wrote:
> > On Tue, May 10, 2011 at 10:50:08AM -0400, Peter Zijlstra wrote:
> > > On Tue, 2011-05-10 at 16:35 +0200, Joerg Roedel wrote:
> > > > @@ -740,6 +740,12 @@ parse_event_modifier(const char **strp, struct perf_event_attr *attr)
> > > > if (!exclude)
> > > > exclude = eu = ek = eh = 1;
> > > > eh = 0;
> > > > + } else if (*str == 'G') {
> > > > + eg = 0;
> > > > + ehst = 1;
> > > > + } else if (*str == 'H') {
> > > > + eg = 1;
> > > > + ehst = 0;
> > >
> > > This doesn't match the existing exclude logic, also eH and eG come to
> > > mind.
> >
> > OK, eH and eG seems like a better choice. Regarding the logic I
> > explictly decided to do it this way. The reason is that guest/host
> > counting is orthogonal to user/kernel/hv counting. You can decide to
> > only count guest-kernel for example. And if a user just specifies
> > -e cycles:G this would automatically exlucde user and kernel counting.
> > This didn't make sense to me so I decided to keep the logic seperate for
> > guest/host exclusions.
>
> OK, so the changelog lacked that bit of information ;-)
Okay, so I add this information to the changelog.
> How about you do something like:
>
>
>
> + } else if (*str == 'G') {
> + if (!excl_GH)
> + excl_GH = eH = eG = 1;
> + eG = 0;
> + } else if (*str == 'H') {
> + if (!excl_GH)
> + excl_GH = eH = eG = 1;
> + eH = 0;
>
> Which mirrors the existing logic but keeps it orthogonal?
Right, it would better fit to the u/k/hv logic. It is not strictly
needed because there are only two excludes here but it makes the code
look more consistent. I'll change it.
> Hmm,. does this nicely integrate with exclude_hv? that seems to want to
> be grouped with G/H.
I intended to re-use the exlude_hv bit originally, but then I looked
into how this bit is used. On PPC it looks like this bit is set when
Linux itself runs as a guest to exclude the hypervisor code being
profiled. The meaning here is different (beacause Linux itself is the
hypervisor) and I wanted to avoid different semantics for this bit
across architectures. So I introduces seperate bits.
The exclude_hv bit can be used when we have some kind of perf-ctr
support for KVM guests.
Regards,
Joerg
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