Re: [PATCH 08/10] perf_event: Optimize the constraint searching bits

[Stephane Eranian <eranian@google.com>]

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On Fri, Jan 22, 2010 at 4:50 PM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:> Instead of copying bitmasks around, pass pointers to the constraint structure.>The reason I changed that is because of the AMD situation where constraintsare dynamically generated. So we need to get some storage from somwhere.See my AMD NB patch,

> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>> LKML-Reference: <new-submission>> --->  arch/x86/kernel/cpu/perf_event.c |   81 ++++++++++++++++++--------------------->  1 file changed, 38 insertions(+), 43 deletions(-)>> Index: linux-2.6/arch/x86/kernel/cpu/perf_event.c> ===================================================================> --- linux-2.6.orig/arch/x86/kernel/cpu/perf_event.c> +++ linux-2.6/arch/x86/kernel/cpu/perf_event.c> @@ -135,12 +138,14 @@ struct x86_pmu {>        u64             intel_ctrl;>        void            (*enable_bts)(u64 config);>        void            (*disable_bts)(void);> -       void            (*get_event_constraints)(struct cpu_hw_events *cpuc,> -                                                struct perf_event *event,> -                                                unsigned long *idxmsk);> +> +       struct event_constraint *> +                       (*get_event_constraints)(struct cpu_hw_events *cpuc,> +                                                struct perf_event *event);> +>        void            (*put_event_constraints)(struct cpu_hw_events *cpuc,>                                                 struct perf_event *event);> -       const struct event_constraint *event_constraints;> +       struct event_constraint *event_constraints;>  };>>  static struct x86_pmu x86_pmu __read_mostly;> @@ -1244,18 +1249,16 @@ static inline int is_x86_event(struct pe>  static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)>  {>        int i, j , w, num;> -       int weight, wmax;> -       unsigned long *c;> -       unsigned long constraints[X86_PMC_IDX_MAX][BITS_TO_LONGS(X86_PMC_IDX_MAX)];> +       int weight, wmax;> +       struct event_constraint *c, *constraints[X86_PMC_IDX_MAX];>        unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)];>        struct hw_perf_event *hwc;>>        bitmap_zero(used_mask, X86_PMC_IDX_MAX);>>        for (i = 0; i < n; i++) {> -               x86_pmu.get_event_constraints(cpuc,> -                                             cpuc->event_list[i],> -                                             constraints[i]);> +               constraints[i] => +                 x86_pmu.get_event_constraints(cpuc, cpuc->event_list[i]);>        }>>        /*> @@ -1270,7 +1273,7 @@ static int x86_schedule_events(struct cp>                        break;>>                /* constraint still honored */> -               if (!test_bit(hwc->idx, c))> +               if (!test_bit(hwc->idx, c->idxmsk))>                        break;>>                /* not already used */> @@ -1323,11 +1326,11 @@ static int x86_schedule_events(struct cp>                        c = constraints[i];>                        hwc = &cpuc->event_list[i]->hw;>> -                       weight = bitmap_weight(c, X86_PMC_IDX_MAX);> +                       weight = bitmap_weight(c->idxmsk, X86_PMC_IDX_MAX);>                        if (weight != w)>                                continue;>> -                       for_each_bit(j, c, X86_PMC_IDX_MAX) {> +                       for_each_bit(j, c->idxmsk, X86_PMC_IDX_MAX) {>                                if (!test_bit(j, used_mask))>                                        break;>                        }> @@ -2165,11 +2167,13 @@ perf_event_nmi_handler(struct notifier_b>        return NOTIFY_STOP;>  }>> +static struct event_constraint unconstrained;> +>  static struct event_constraint bts_constraint =>        EVENT_CONSTRAINT(0, 1ULL << X86_PMC_IDX_FIXED_BTS, 0);>> -static int intel_special_constraints(struct perf_event *event,> -                                    unsigned long *idxmsk)> +static struct event_constraint *> +intel_special_constraints(struct perf_event *event)>  {>        unsigned int hw_event;>> @@ -2179,46 +2183,34 @@ static int intel_special_constraints(str>                      x86_pmu.event_map(PERF_COUNT_HW_BRANCH_INSTRUCTIONS)) &&>                     (event->hw.sample_period == 1))) {>> -               bitmap_copy((unsigned long *)idxmsk,> -                           (unsigned long *)bts_constraint.idxmsk,> -                           X86_PMC_IDX_MAX);> -               return 1;> +               return &bts_constraint;>        }> -       return 0;> +       return NULL;>  }>> -static void intel_get_event_constraints(struct cpu_hw_events *cpuc,> -                                       struct perf_event *event,> -                                       unsigned long *idxmsk)> +static struct event_constraint *> +intel_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)>  {> -       const struct event_constraint *c;> +       struct event_constraint *c;>> -       /*> -        * cleanup bitmask> -        */> -       bitmap_zero(idxmsk, X86_PMC_IDX_MAX);> -> -       if (intel_special_constraints(event, idxmsk))> -               return;> +       c = intel_special_constraints(event);> +       if (c)> +               return c;>>        if (x86_pmu.event_constraints) {>                for_each_event_constraint(c, x86_pmu.event_constraints) {> -                       if ((event->hw.config & c->cmask) == c->code) {> -                               bitmap_copy(idxmsk, c->idxmsk, X86_PMC_IDX_MAX);> -                               return;> -                       }> +                       if ((event->hw.config & c->cmask) == c->code)> +                               return c;>                }>        }> -       /* no constraints, means supports all generic counters */> -       bitmap_fill((unsigned long *)idxmsk, x86_pmu.num_events);> +> +       return &unconstrained;>  }>> -static void amd_get_event_constraints(struct cpu_hw_events *cpuc,> -                                     struct perf_event *event,> -                                     unsigned long *idxmsk)> +static struct event_constraint *> +amd_get_event_constraints(struct cpu_hw_events *cpuc, struct perf_event *event)>  {> -       /* no constraints, means supports all generic counters */> -       bitmap_fill(idxmsk, x86_pmu.num_events);> +       return &unconstrained;>  }>>  static int x86_event_sched_in(struct perf_event *event,> @@ -2586,6 +2578,9 @@ void __init init_hw_perf_events(void)>        perf_events_lapic_init();>        register_die_notifier(&perf_event_nmi_notifier);>> +       unconstrained = (struct event_constraint)> +               EVENT_CONSTRAINT(0, (1ULL << x86_pmu.num_events) - 1, 0);> +>        pr_info("... version:                %d\n",     x86_pmu.version);>        pr_info("... bit width:              %d\n",     x86_pmu.event_bits);>        pr_info("... generic registers:      %d\n",     x86_pmu.num_events);>> -->>


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