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SubjectRe: [PATCH RESEND V5 2/6] perf, amd: Generalize northbridge constraints code for family 15h
From
On Thu, Jan 10, 2013 at 8:50 PM, Jacob Shin <jacob.shin@amd.com> wrote:
> From: Robert Richter <rric@kernel.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@kernel.org>
> Signed-off-by: Jacob Shin <jacob.shin@amd.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.


> 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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