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Date: Fri, 25 Jan 2013 09:56:40 -0600
From: Jacob Shin <jacob.shin@....com>
To: Stephane Eranian <eranian@...gle.com>
CC: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>, x86 <x86@...nel.org>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Paul Mackerras <paulus@...ba.org>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
LKML <linux-kernel@...r.kernel.org>,
Robert Richter <rric@...nel.org>
Subject: Re: [PATCH RESEND V5 2/6] perf, amd: Generalize northbridge
constraints code for family 15h
On Fri, Jan 25, 2013 at 12:07:40PM +0100, Stephane Eranian wrote:
> On Thu, Jan 10, 2013 at 8:50 PM, Jacob Shin <jacob.shin@....com> wrote:
> > From: Robert Richter <rric@...nel.org>
> >
> > Generalize northbridge constraints code for family 10h so that later
> > we can reuse the same code path with other AMD processor families that
> > have the same northbridge event constraints.
> >
> > Signed-off-by: Robert Richter <rric@...nel.org>
> > Signed-off-by: Jacob Shin <jacob.shin@....com>
> > ---
> > arch/x86/kernel/cpu/perf_event_amd.c | 43 ++++++++++++++++++++--------------
> > 1 file changed, 25 insertions(+), 18 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
> > index e7963c7..9541fe5 100644
> > --- a/arch/x86/kernel/cpu/perf_event_amd.c
> > +++ b/arch/x86/kernel/cpu/perf_event_amd.c
> > @@ -188,20 +188,13 @@ static inline int amd_has_nb(struct cpu_hw_events *cpuc)
> > return nb && nb->nb_id != -1;
> > }
> >
> > -static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
> > - struct perf_event *event)
> > +static void __amd_put_nb_event_constraints(struct cpu_hw_events *cpuc,
> > + struct perf_event *event)
> > {
> > - struct hw_perf_event *hwc = &event->hw;
> > struct amd_nb *nb = cpuc->amd_nb;
> > int i;
> >
> > /*
> > - * only care about NB events
> > - */
> > - if (!(amd_has_nb(cpuc) && amd_is_nb_event(hwc)))
> > - return;
> > -
> > - /*
> > * need to scan whole list because event may not have
> > * been assigned during scheduling
> > *
> > @@ -247,12 +240,13 @@ static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
> > *
> > * Given that resources are allocated (cmpxchg), they must be
> > * eventually freed for others to use. This is accomplished by
> > - * calling amd_put_event_constraints().
> > + * calling __amd_put_nb_event_constraints()
> > *
> > * Non NB events are not impacted by this restriction.
> > */
> > static struct event_constraint *
> > -amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
> > +__amd_get_nb_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event,
> > + struct event_constraint *c)
> > {
> > struct hw_perf_event *hwc = &event->hw;
> > struct amd_nb *nb = cpuc->amd_nb;
> > @@ -260,12 +254,6 @@ amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
> > int idx, new = -1;
> >
> > /*
> > - * if not NB event or no NB, then no constraints
> > - */
> > - if (!(amd_has_nb(cpuc) && amd_is_nb_event(hwc)))
> > - return &unconstrained;
> > -
> > - /*
> > * detect if already present, if so reuse
> > *
> > * cannot merge with actual allocation
> > @@ -275,7 +263,7 @@ amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
> > * because of successive calls to x86_schedule_events() from
> > * hw_perf_group_sched_in() without hw_perf_enable()
> > */
> > - for (idx = 0; idx < x86_pmu.num_counters; idx++) {
> > + for_each_set_bit(idx, c->idxmsk, X86_PMC_IDX_MAX) {
>
> So here you're using X86_PMC_IDX_MAX but in
> __amd_put_nb_event_constraints() you're using
> x86_pmu.num_counters.
>
> There is implicit assumption in the AMD code the counters index
> namespace is contiguous. That
> means the uncore counters show up right after the core counters. On
> Fam15h, that would be NB
> counters start at index 6, on Fam10h at index 4. In that case, the
> constraint mask cannot have bits set
> beyond num_counters, so why not use that limit in
> amd_get_event_constraints()? It would significantly
> cut down on the number of iterations in the loop from 64 down to 10 on Fam15h.
Yes, you are right, I will change that in V6.
Thanks,
>
>
> > if (new == -1 || hwc->idx == idx)
> > /* assign free slot, prefer hwc->idx */
> > old = cmpxchg(nb->owners + idx, NULL, event);
> > @@ -391,6 +379,25 @@ static void amd_pmu_cpu_dead(int cpu)
> > }
> > }
> >
> > +static struct event_constraint *
> > +amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)
> > +{
> > + /*
> > + * if not NB event or no NB, then no constraints
> > + */
> > + if (!(amd_has_nb(cpuc) && amd_is_nb_event(&event->hw)))
> > + return &unconstrained;
> > +
> > + return __amd_get_nb_event_constraints(cpuc, event, &unconstrained);
> > +}
> > +
> > +static void amd_put_event_constraints(struct cpu_hw_events *cpuc,
> > + struct perf_event *event)
> > +{
> > + if (amd_has_nb(cpuc) && amd_is_nb_event(&event->hw))
> > + __amd_put_nb_event_constraints(cpuc, event);
> > +}
> > +
> > PMU_FORMAT_ATTR(event, "config:0-7,32-35");
> > PMU_FORMAT_ATTR(umask, "config:8-15" );
> > PMU_FORMAT_ATTR(edge, "config:18" );
> > --
> > 1.7.9.5
> >
> >
>
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