Re: [PATCH 3/8] drm/i915/pmu: Expose a PMU interface for perf queries

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Quoting Tvrtko Ursulin (2017-09-25 16:15:38)
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> 
> From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> From: Dmitry Rogozhkin <dmitry.v.rogozhkin@xxxxxxxxx>
> 
> The first goal is to be able to measure GPU (and invidual ring) busyness
> without having to poll registers from userspace. (Which not only incurs
> holding the forcewake lock indefinitely, perturbing the system, but also
> runs the risk of hanging the machine.) As an alternative we can use the
> perf event counter interface to sample the ring registers periodically
> and send those results to userspace.
> 
> Functionality we are exporting to userspace is via the existing perf PMU
> API and can be exercised via the existing tools. For example:
> 
>   perf stat -a -e i915/rcs0-busy/ -I 1000
> 
> Will print the render engine busynnes once per second. All the performance
> counters can be enumerated (perf list) and have their unit of measure
> correctly reported in sysfs.
> 
> v1-v2 (Chris Wilson):
> 
> v2: Use a common timer for the ring sampling.
> 
> v3: (Tvrtko Ursulin)
>  * Decouple uAPI from i915 engine ids.
>  * Complete uAPI defines.
>  * Refactor some code to helpers for clarity.
>  * Skip sampling disabled engines.
>  * Expose counters in sysfs.
>  * Pass in fake regs to avoid null ptr deref in perf core.
>  * Convert to class/instance uAPI.
>  * Use shared driver code for rc6 residency, power and frequency.
> 
> v4: (Dmitry Rogozhkin)
>  * Register PMU with .task_ctx_nr=perf_invalid_context
>  * Expose cpumask for the PMU with the single CPU in the mask
>  * Properly support pmu->stop(): it should call pmu->read()
>  * Properly support pmu->del(): it should call stop(event, PERF_EF_UPDATE)
>  * Introduce refcounting of event subscriptions.
>  * Make pmu.busy_stats a refcounter to avoid busy stats going away
>    with some deleted event.
>  * Expose cpumask for i915 PMU to avoid multiple events creation of
>    the same type followed by counter aggregation by perf-stat.
>  * Track CPUs getting online/offline to migrate perf context. If (likely)
>    cpumask will initially set CPU0, CONFIG_BOOTPARAM_HOTPLUG_CPU0 will be
>    needed to see effect of CPU status tracking.
>  * End result is that only global events are supported and perf stat
>    works correctly.
>  * Deny perf driver level sampling - it is prohibited for uncore PMU.
> 
> v5: (Tvrtko Ursulin)
> 
>  * Don't hardcode number of engine samplers.
>  * Rewrite event ref-counting for correctness and simplicity.
>  * Store initial counter value when starting already enabled events
>    to correctly report values to all listeners.
>  * Fix RC6 residency readout.
>  * Comments, GPL header.
> 
> v6:
>  * Add missing entry to v4 changelog.
>  * Fix accounting in CPU hotplug case by copying the approach from
>    arch/x86/events/intel/cstate.c. (Dmitry Rogozhkin)
> 
> v7:
>  * Log failure message only on failure.
>  * Remove CPU hotplug notification state on unregister.
> 
> v8:
>  * Fix error unwind on failed registration.
>  * Checkpatch cleanup.
> 
> v9:
>  * Drop the energy metric, it is available via intel_rapl_perf.
>    (Ville Syrjälä)
>  * Use HAS_RC6(p). (Chris Wilson)
>  * Handle unsupported non-engine events. (Dmitry Rogozhkin)
>  * Rebase for intel_rc6_residency_ns needing caller managed
>    runtime pm.
>  * Drop HAS_RC6 checks from the read callback since creating those
>    events will be rejected at init time already.
>  * Add counter units to sysfs so perf stat output is nicer.
>  * Cleanup the attribute tables for brevity and readability.
> 
> v10:
>  * Fixed queued accounting.
> 
> v11:
>  * Move intel_engine_lookup_user to intel_engine_cs.c
>  * Commit update. (Joonas Lahtinen)
> 
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Signed-off-by: Dmitry Rogozhkin <dmitry.v.rogozhkin@xxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Dmitry Rogozhkin <dmitry.v.rogozhkin@xxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/i915/Makefile           |   1 +
>  drivers/gpu/drm/i915/i915_drv.c         |   2 +
>  drivers/gpu/drm/i915/i915_drv.h         |  78 ++++
>  drivers/gpu/drm/i915/i915_pmu.c         | 707 ++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/i915_reg.h         |   3 +
>  drivers/gpu/drm/i915/intel_engine_cs.c  |  35 ++
>  drivers/gpu/drm/i915/intel_ringbuffer.h |  25 ++
>  include/uapi/drm/i915_drm.h             |  57 +++
>  8 files changed, 908 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/i915_pmu.c
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 5182e3d5557d..5c6013961b3b 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -26,6 +26,7 @@ i915-y := i915_drv.o \
>  
>  i915-$(CONFIG_COMPAT)   += i915_ioc32.o
>  i915-$(CONFIG_DEBUG_FS) += i915_debugfs.o intel_pipe_crc.o
> +i915-$(CONFIG_PERF_EVENTS) += i915_pmu.o
>  
>  # GEM code
>  i915-y += i915_cmd_parser.o \
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 7056bb299dc6..03bbe23e4df8 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1200,6 +1200,7 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
>         struct drm_device *dev = &dev_priv->drm;
>  
>         i915_gem_shrinker_init(dev_priv);
> +       i915_pmu_register(dev_priv);
>  
>         /*
>          * Notify a valid surface after modesetting,
> @@ -1254,6 +1255,7 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
>         intel_opregion_unregister(dev_priv);
>  
>         i915_perf_unregister(dev_priv);
> +       i915_pmu_unregister(dev_priv);
>  
>         i915_teardown_sysfs(dev_priv);
>         i915_guc_log_unregister(dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 6143a709c605..a40c314eed5f 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -40,6 +40,7 @@
>  #include <linux/hash.h>
>  #include <linux/intel-iommu.h>
>  #include <linux/kref.h>
> +#include <linux/perf_event.h>
>  #include <linux/pm_qos.h>
>  #include <linux/reservation.h>
>  #include <linux/shmem_fs.h>
> @@ -2198,6 +2199,70 @@ struct intel_cdclk_state {
>         unsigned int cdclk, vco, ref;
>  };
>  
> +enum {
> +       __I915_SAMPLE_FREQ_ACT = 0,
> +       __I915_SAMPLE_FREQ_REQ,
> +       __I915_NUM_PMU_SAMPLERS
> +};
> +
> +/**
> + * How many different events we track in the global PMU mask.
> + *
> + * It is also used to know to needed number of event reference counters.
> + */
> +#define I915_PMU_MASK_BITS \
> +       ((1 << I915_PMU_SAMPLE_BITS) + \
> +        (I915_PMU_LAST + 1 - __I915_PMU_OTHER(0)))
> +
> +struct i915_pmu {
> +       /**
> +        * @node: List node for CPU hotplug handling.
> +        */
> +       struct hlist_node node;
> +       /**
> +        * @base: PMU base.
> +        */
> +       struct pmu base;
> +       /**
> +        * @lock: Lock protecting enable mask and ref count handling.
> +        */
> +       spinlock_t lock;
> +       /**
> +        * @timer: Timer for internal i915 PMU sampling.
> +        */
> +       struct hrtimer timer;
> +       /**
> +        * @enable: Bitmask of all currently enabled events.
> +        *
> +        * Bits are derived from uAPI event numbers in a way that low 16 bits
> +        * correspond to engine event _sample_ _type_ (I915_SAMPLE_QUEUED is
> +        * bit 0), and higher bits correspond to other events (for instance
> +        * I915_PMU_ACTUAL_FREQUENCY is bit 16 etc).
> +        *
> +        * In other words, low 16 bits are not per engine but per engine
> +        * sampler type, while the upper bits are directly mapped to other
> +        * event types.
> +        */
> +       u64 enable;
> +       /**
> +        * @enable_count: Reference counts for the enabled events.
> +        *
> +        * Array indices are mapped in the same way as bits in the @enable field
> +        * and they are used to control sampling on/off when multiple clients
> +        * are using the PMU API.
> +        */
> +       unsigned int enable_count[I915_PMU_MASK_BITS];
> +       /**
> +        * @sample: Current counter value for i915 events which need sampling.
> +        *
> +        * These counters are updated from the i915 PMU sampling timer.
> +        *
> +        * Only global counters are held here, while the per-engine ones are in
> +        * struct intel_engine_cs.
> +        */
> +       u64 sample[__I915_NUM_PMU_SAMPLERS];
> +};
> +
>  struct drm_i915_private {
>         struct drm_device drm;
>  
> @@ -2246,6 +2311,8 @@ struct drm_i915_private {
>         struct pci_dev *bridge_dev;
>         struct i915_gem_context *kernel_context;
>         struct intel_engine_cs *engine[I915_NUM_ENGINES];
> +       struct intel_engine_cs *engine_class[MAX_ENGINE_CLASS + 1]
> +                                           [MAX_ENGINE_INSTANCE + 1];
>         struct i915_vma *semaphore;
>  
>         struct drm_dma_handle *status_page_dmah;
> @@ -2708,6 +2775,8 @@ struct drm_i915_private {
>                 int     irq;
>         } lpe_audio;
>  
> +       struct i915_pmu pmu;
> +
>         /*
>          * NOTE: This is the dri1/ums dungeon, don't add stuff here. Your patch
>          * will be rejected. Instead look for a better place.
> @@ -3932,6 +4001,15 @@ extern void i915_perf_fini(struct drm_i915_private *dev_priv);
>  extern void i915_perf_register(struct drm_i915_private *dev_priv);
>  extern void i915_perf_unregister(struct drm_i915_private *dev_priv);
>  
> +/* i915_pmu.c */
> +#ifdef CONFIG_PERF_EVENTS
> +void i915_pmu_register(struct drm_i915_private *i915);
> +void i915_pmu_unregister(struct drm_i915_private *i915);
> +#else
> +static inline void i915_pmu_register(struct drm_i915_private *i915) {}
> +static inline void i915_pmu_unregister(struct drm_i915_private *i915) {}
> +#endif
> +
>  /* i915_suspend.c */
>  extern int i915_save_state(struct drm_i915_private *dev_priv);
>  extern int i915_restore_state(struct drm_i915_private *dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> new file mode 100644
> index 000000000000..cf1406fbc215
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -0,0 +1,707 @@
> +/*
> + * Copyright © 2017 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + */
> +
> +#include <linux/perf_event.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "i915_drv.h"
> +#include "intel_ringbuffer.h"
> +
> +/* Frequency for the sampling timer for events which need it. */
> +#define FREQUENCY 200
> +#define PERIOD max_t(u64, 10000, NSEC_PER_SEC / FREQUENCY)
> +
> +#define ENGINE_SAMPLE_MASK \
> +       (BIT(I915_SAMPLE_QUEUED) | \
> +        BIT(I915_SAMPLE_BUSY) | \
> +        BIT(I915_SAMPLE_WAIT) | \
> +        BIT(I915_SAMPLE_SEMA))
> +
> +#define ENGINE_SAMPLE_BITS (1 << I915_PMU_SAMPLE_BITS)
> +
> +static cpumask_t i915_pmu_cpumask = CPU_MASK_NONE;
> +
> +static u8 engine_config_sample(u64 config)
> +{
> +       return config & I915_PMU_SAMPLE_MASK;
> +}
> +
> +static u8 engine_event_sample(struct perf_event *event)
> +{
> +       return engine_config_sample(event->attr.config);
> +}
> +
> +static u8 engine_event_class(struct perf_event *event)
> +{
> +       return (event->attr.config >> I915_PMU_CLASS_SHIFT) & 0xff;
> +}
> +
> +static u8 engine_event_instance(struct perf_event *event)
> +{
> +       return (event->attr.config >> I915_PMU_SAMPLE_BITS) & 0xff;
> +}
> +
> +static bool is_engine_config(u64 config)
> +{
> +       return config < __I915_PMU_OTHER(0);
> +}
> +
> +static unsigned int config_enabled_bit(u64 config)
> +{
> +       if (is_engine_config(config))
> +               return engine_config_sample(config);
> +       else
> +               return ENGINE_SAMPLE_BITS + (config - __I915_PMU_OTHER(0));
> +}
> +
> +static u64 config_enabled_mask(u64 config)
> +{
> +       return BIT_ULL(config_enabled_bit(config));
> +}
> +
> +static bool is_engine_event(struct perf_event *event)
> +{
> +       return is_engine_config(event->attr.config);
> +}
> +
> +static unsigned int event_enabled_bit(struct perf_event *event)
> +{
> +       return config_enabled_bit(event->attr.config);
> +}
> +
> +static bool grab_forcewake(struct drm_i915_private *i915, bool fw)
> +{
> +       if (!fw)
> +               intel_uncore_forcewake_get(i915, FORCEWAKE_ALL);
> +
> +       return true;
> +}
> +
> +static void engines_sample(struct drm_i915_private *dev_priv)
> +{
> +       struct intel_engine_cs *engine;
> +       enum intel_engine_id id;
> +       bool fw = false;
> +
> +       if ((dev_priv->pmu.enable & ENGINE_SAMPLE_MASK) == 0)
> +               return;
> +
> +       if (!dev_priv->gt.awake)
> +               return;
> +
> +       if (!intel_runtime_pm_get_if_in_use(dev_priv))
> +               return;
> +
> +       for_each_engine(engine, dev_priv, id) {
> +               u32 current_seqno = intel_engine_get_seqno(engine);
> +               u32 last_seqno = intel_engine_last_submit(engine);
> +               u32 enable = engine->pmu.enable;
> +
> +               if (i915_seqno_passed(current_seqno, last_seqno))
> +                       continue;
> +
> +               if ((enable & BIT(I915_SAMPLE_QUEUED)) &&
> +                   (last_seqno - 1 > current_seqno))

Hmm, this isn't queued. This is more than one rq submitted to hw.

Do you want total inflight (including waiting-for-fences)? That would be
engine->timeline->inflight_seqnos (additional problem in its laziness).

Hard to distinguish all other cases, but last - current is susceptible
to not treating all ready requests as being queued. And miscounts on
legacy across semaphores (which you've excluded for execlists).

Aiui you want

diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
index 4eb1a76731b2..19b8b31afbbc 100644
--- a/drivers/gpu/drm/i915/i915_gem_request.c
+++ b/drivers/gpu/drm/i915/i915_gem_request.c
@@ -477,6 +477,7 @@ void __i915_gem_request_submit(struct drm_i915_gem_request *request)
        engine->emit_breadcrumb(request,
                                request->ring->vaddr + request->postfix);
 
+       atomic_dec(&request->engine->queued);
        spin_lock(&request->timeline->lock);
        list_move_tail(&request->link, &timeline->requests);
        spin_unlock(&request->timeline->lock);
@@ -525,6 +526,7 @@ void __i915_gem_request_unsubmit(struct drm_i915_gem_request *request)
        spin_lock(&timeline->lock);
        list_move(&request->link, &timeline->requests);
        spin_unlock(&timeline->lock);
+       atomic_inc(&request->engine->queued);
 
        /* We don't need to wake_up any waiters on request->execute, they
         * will get woken by any other event or us re-adding this request
@@ -556,6 +558,7 @@ submit_notify(struct i915_sw_fence *fence, enum i915_sw_fence_notify state)
        switch (state) {
        case FENCE_COMPLETE:
                trace_i915_gem_request_submit(request);
+               atomic_inc(&request->engine->queued);
                request->engine->submit_request(request);
                break;
 

That excludes the requests actually in the hw queue, just those in the sw
queue. Or both.


> +                       engine->pmu.sample[I915_SAMPLE_QUEUED] += PERIOD;
> +
> +               if (enable & BIT(I915_SAMPLE_BUSY)) {
> +                       u32 val;
> +
> +                       fw = grab_forcewake(dev_priv, fw);
> +                       val = I915_READ_FW(RING_MI_MODE(engine->mmio_base));
> +                       if (!(val & MODE_IDLE))
> +                               engine->pmu.sample[I915_SAMPLE_BUSY] += PERIOD;
> +               }
> +
> +               if (enable & (BIT(I915_SAMPLE_WAIT) | BIT(I915_SAMPLE_SEMA))) {
> +                       u32 val;
> +
> +                       fw = grab_forcewake(dev_priv, fw);
> +                       val = I915_READ_FW(RING_CTL(engine->mmio_base));
> +                       if ((enable & BIT(I915_SAMPLE_WAIT)) &&
> +                           (val & RING_WAIT))
> +                               engine->pmu.sample[I915_SAMPLE_WAIT] += PERIOD;
> +                       if ((enable & BIT(I915_SAMPLE_SEMA)) &&
> +                           (val & RING_WAIT_SEMAPHORE))
> +                               engine->pmu.sample[I915_SAMPLE_SEMA] += PERIOD;
> +               }
> +       }
> +
> +       if (fw)
> +               intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
> +       intel_runtime_pm_put(dev_priv);
> +}
> +
> +static void frequency_sample(struct drm_i915_private *dev_priv)
> +{
> +       if (dev_priv->pmu.enable &
> +           config_enabled_mask(I915_PMU_ACTUAL_FREQUENCY)) {
> +               u64 val;
> +
> +               val = dev_priv->rps.cur_freq;
> +               if (dev_priv->gt.awake &&
> +                   intel_runtime_pm_get_if_in_use(dev_priv)) {
> +                       val = intel_get_cagf(dev_priv,
> +                                            I915_READ_NOTRACE(GEN6_RPSTAT1));
> +                       intel_runtime_pm_put(dev_priv);
> +               }
> +               val = intel_gpu_freq(dev_priv, val);
> +               dev_priv->pmu.sample[__I915_SAMPLE_FREQ_ACT] += val * PERIOD;
> +       }
> +
> +       if (dev_priv->pmu.enable &
> +           config_enabled_mask(I915_PMU_REQUESTED_FREQUENCY)) {
> +               u64 val = intel_gpu_freq(dev_priv, dev_priv->rps.cur_freq);
> +
> +               dev_priv->pmu.sample[__I915_SAMPLE_FREQ_REQ] += val * PERIOD;
> +       }

Ok. Do we need a comment to explain the importance of averaging here?
Should we be doing trapezium integration?

> +}
> +
> +static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
> +{
> +       struct drm_i915_private *i915 =
> +               container_of(hrtimer, struct drm_i915_private, pmu.timer);
> +
> +       if (i915->pmu.enable == 0)
> +               return HRTIMER_NORESTART;
> +
> +       engines_sample(i915);
> +       frequency_sample(i915);
> +
> +       hrtimer_forward_now(hrtimer, ns_to_ktime(PERIOD));
> +       return HRTIMER_RESTART;
> +}
> +
> +static u64 count_interrupts(struct drm_i915_private *i915)
> +{
> +       /* open-coded kstat_irqs() */
> +       struct irq_desc *desc = irq_to_desc(i915->drm.pdev->irq);
> +       u64 sum = 0;
> +       int cpu;
> +
> +       if (!desc || !desc->kstat_irqs)
> +               return 0;
> +
> +       for_each_possible_cpu(cpu)
> +               sum += *per_cpu_ptr(desc->kstat_irqs, cpu);
> +
> +       return sum;
> +}
> +
> +static void i915_pmu_event_destroy(struct perf_event *event)
> +{
> +       WARN_ON(event->parent);
> +}
> +
> +static int engine_event_init(struct perf_event *event)
> +{
> +       struct drm_i915_private *i915 =
> +               container_of(event->pmu, typeof(*i915), pmu.base);
> +
> +       if (!intel_engine_lookup_user(i915, engine_event_class(event),
> +                                     engine_event_instance(event)))
> +               return -ENODEV;
> +
> +       switch (engine_event_sample(event)) {
> +       case I915_SAMPLE_QUEUED:
> +       case I915_SAMPLE_BUSY:
> +       case I915_SAMPLE_WAIT:
> +               break;
> +       case I915_SAMPLE_SEMA:
> +               if (INTEL_GEN(i915) < 6)
> +                       return -ENODEV;
> +               break;
> +       default:
> +               return -ENOENT;
> +       }
> +
> +       return 0;
> +}
> +
> +static int i915_pmu_event_init(struct perf_event *event)
> +{
> +       struct drm_i915_private *i915 =
> +               container_of(event->pmu, typeof(*i915), pmu.base);
> +       int cpu, ret;
> +
> +       if (event->attr.type != event->pmu->type)
> +               return -ENOENT;
> +
> +       /* unsupported modes and filters */
> +       if (event->attr.sample_period) /* no sampling */
> +               return -EINVAL;
> +
> +       if (has_branch_stack(event))
> +               return -EOPNOTSUPP;
> +
> +       if (event->cpu < 0)
> +               return -EINVAL;
> +
> +       cpu = cpumask_any_and(&i915_pmu_cpumask,
> +                             topology_sibling_cpumask(event->cpu));
> +       if (cpu >= nr_cpu_ids)
> +               return -ENODEV;
> +
> +       if (is_engine_event(event)) {
> +               ret = engine_event_init(event);
> +       } else {
> +               ret = 0;
> +               switch (event->attr.config) {
> +               case I915_PMU_INTERRUPTS:
> +                       break;
> +               case I915_PMU_ACTUAL_FREQUENCY:
> +                       if (IS_VALLEYVIEW(i915) || IS_CHERRYVIEW(i915))
> +                                /* Requires a mutex for sampling! */
> +                               ret = -ENODEV;
> +               case I915_PMU_REQUESTED_FREQUENCY:
> +                       if (INTEL_GEN(i915) < 6)
> +                               ret = -ENODEV;
> +                       break;
> +               case I915_PMU_RC6_RESIDENCY:
> +                       if (!HAS_RC6(i915))
> +                               ret = -ENODEV;
> +                       break;
> +               case I915_PMU_RC6p_RESIDENCY:
> +               case I915_PMU_RC6pp_RESIDENCY:
> +                       if (!HAS_RC6p(i915))
> +                               ret = -ENODEV;

Must introduced you to my HAS_RC6pp() patch.

> +                       break;
> +               default:
> +                       ret = -ENOENT;
> +                       break;
> +               }
> +       }
> +       if (ret)
> +               return ret;
> +
> +       event->cpu = cpu;
> +       if (!event->parent)
> +               event->destroy = i915_pmu_event_destroy;
> +
> +       return 0;
> +}
> +
> +static u64 __i915_pmu_event_read(struct perf_event *event)
> +{
> +       struct drm_i915_private *i915 =
> +               container_of(event->pmu, typeof(*i915), pmu.base);
> +       u64 val = 0;
> +
> +       if (is_engine_event(event)) {
> +               u8 sample = engine_event_sample(event);
> +               struct intel_engine_cs *engine;
> +
> +               engine = intel_engine_lookup_user(i915,
> +                                                 engine_event_class(event),
> +                                                 engine_event_instance(event));
> +
> +               if (WARN_ON_ONCE(!engine)) {
> +                       /* Do nothing */
> +               } else {
> +                       val = engine->pmu.sample[sample];
> +               }
> +       } else {
> +               switch (event->attr.config) {
> +               case I915_PMU_ACTUAL_FREQUENCY:
> +                       val = i915->pmu.sample[__I915_SAMPLE_FREQ_ACT];
> +                       break;
> +               case I915_PMU_REQUESTED_FREQUENCY:
> +                       val = i915->pmu.sample[__I915_SAMPLE_FREQ_REQ];
> +                       break;
> +               case I915_PMU_INTERRUPTS:
> +                       val = count_interrupts(i915);
> +                       break;
> +               case I915_PMU_RC6_RESIDENCY:
> +                       intel_runtime_pm_get(i915);
> +                       val = intel_rc6_residency_ns(i915,
> +                                                    IS_VALLEYVIEW(i915) ?
> +                                                    VLV_GT_RENDER_RC6 :
> +                                                    GEN6_GT_GFX_RC6);
> +                       intel_runtime_pm_put(i915);
> +                       break;
> +               case I915_PMU_RC6p_RESIDENCY:
> +                       intel_runtime_pm_get(i915);
> +                       val = intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6p);
> +                       intel_runtime_pm_put(i915);
> +                       break;
> +               case I915_PMU_RC6pp_RESIDENCY:
> +                       intel_runtime_pm_get(i915);
> +                       val = intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6pp);
> +                       intel_runtime_pm_put(i915);
> +                       break;
> +               }
> +       }

Ok.

> +
> +       return val;
> +}
> +
> +static void i915_pmu_event_read(struct perf_event *event)
> +{
> +       struct hw_perf_event *hwc = &event->hw;
> +       u64 prev, new;
> +
> +again:
> +       prev = local64_read(&hwc->prev_count);
> +       new = __i915_pmu_event_read(event);
> +
> +       if (local64_cmpxchg(&hwc->prev_count, prev, new) != prev)
> +               goto again;
> +
> +       local64_add(new - prev, &event->count);
> +}
> +
> +static void i915_pmu_enable(struct perf_event *event)
> +{
> +       struct drm_i915_private *i915 =
> +               container_of(event->pmu, typeof(*i915), pmu.base);
> +       unsigned int bit = event_enabled_bit(event);
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&i915->pmu.lock, flags);
> +
> +       /*
> +        * Start the sampling timer when enabling the first event.
> +        */
> +       if (i915->pmu.enable == 0)
> +               hrtimer_start_range_ns(&i915->pmu.timer,
> +                                      ns_to_ktime(PERIOD), 0,
> +                                      HRTIMER_MODE_REL_PINNED);
> +
> +       /*
> +        * Update the bitmask of enabled events and increment
> +        * the event reference counter.
> +        */
> +       GEM_BUG_ON(bit >= I915_PMU_MASK_BITS);
> +       GEM_BUG_ON(i915->pmu.enable_count[bit] == ~0);
> +       i915->pmu.enable |= BIT_ULL(bit);
> +       i915->pmu.enable_count[bit]++;
> +
> +       /*
> +        * For per-engine events the bitmask and reference counting
> +        * is stored per engine.
> +        */
> +       if (is_engine_event(event)) {
> +               u8 sample = engine_event_sample(event);
> +               struct intel_engine_cs *engine;
> +
> +               engine = intel_engine_lookup_user(i915,
> +                                                 engine_event_class(event),
> +                                                 engine_event_instance(event));
> +               GEM_BUG_ON(!engine);
> +               engine->pmu.enable |= BIT(sample);
> +
> +               GEM_BUG_ON(sample >= I915_PMU_SAMPLE_BITS);
> +               GEM_BUG_ON(engine->pmu.enable_count[sample] == ~0);
> +               engine->pmu.enable_count[sample]++;
> +       }
> +
> +       /*
> +        * Store the current counter value so we can report the correct delta
> +        * for all listeners. Even when the event was already enabled and has
> +        * an existing non-zero value.
> +        */
> +       local64_set(&event->hw.prev_count, __i915_pmu_event_read(event));
> +
> +       spin_unlock_irqrestore(&i915->pmu.lock, flags);
> +}
> +
> +static void i915_pmu_disable(struct perf_event *event)
> +{
> +       struct drm_i915_private *i915 =
> +               container_of(event->pmu, typeof(*i915), pmu.base);
> +       unsigned int bit = event_enabled_bit(event);
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&i915->pmu.lock, flags);
> +
> +       if (is_engine_event(event)) {
> +               u8 sample = engine_event_sample(event);
> +               struct intel_engine_cs *engine;
> +
> +               engine = intel_engine_lookup_user(i915,
> +                                                 engine_event_class(event),
> +                                                 engine_event_instance(event));
> +               GEM_BUG_ON(!engine);
> +               GEM_BUG_ON(sample >= I915_PMU_SAMPLE_BITS);
> +               GEM_BUG_ON(engine->pmu.enable_count[sample] == 0);
> +               /*
> +                * Decrement the reference count and clear the enabled
> +                * bitmask when the last listener on an event goes away.
> +                */
> +               if (--engine->pmu.enable_count[sample] == 0)
> +                       engine->pmu.enable &= ~BIT(sample);
> +       }
> +
> +       GEM_BUG_ON(bit >= I915_PMU_MASK_BITS);
> +       GEM_BUG_ON(i915->pmu.enable_count[bit] == 0);
> +       /*
> +        * Decrement the reference count and clear the enabled
> +        * bitmask when the last listener on an event goes away.
> +        */
> +       if (--i915->pmu.enable_count[bit] == 0)
> +               i915->pmu.enable &= ~BIT_ULL(bit);
> +
> +       spin_unlock_irqrestore(&i915->pmu.lock, flags);

Ok.
> +}
> +
> +static void i915_pmu_event_start(struct perf_event *event, int flags)
> +{
> +       i915_pmu_enable(event);
> +       event->hw.state = 0;
> +}
> +
> +static void i915_pmu_event_stop(struct perf_event *event, int flags)
> +{
> +       if (flags & PERF_EF_UPDATE)
> +               i915_pmu_event_read(event);
> +       i915_pmu_disable(event);
> +       event->hw.state = PERF_HES_STOPPED;

Never did understand the differences in perf start/stop, enable/disable,
add/del :)

> +}
> +
> +static int i915_pmu_event_add(struct perf_event *event, int flags)
> +{
> +       if (flags & PERF_EF_START)
> +               i915_pmu_event_start(event, flags);
> +
> +       return 0;
> +}
> +
> +static void i915_pmu_event_del(struct perf_event *event, int flags)
> +{
> +       i915_pmu_event_stop(event, PERF_EF_UPDATE);
> +}
> +
> +static int i915_pmu_event_event_idx(struct perf_event *event)
> +{
> +       return 0;
> +}
> +
> +static ssize_t i915_pmu_format_show(struct device *dev,
> +                                   struct device_attribute *attr, char *buf)
> +{
> +       struct dev_ext_attribute *eattr;
> +
> +       eattr = container_of(attr, struct dev_ext_attribute, attr);
> +       return sprintf(buf, "%s\n", (char *)eattr->var);
> +}
> +
> +#define I915_PMU_FORMAT_ATTR(_name, _config) \
> +       (&((struct dev_ext_attribute[]) { \
> +               { .attr = __ATTR(_name, 0444, i915_pmu_format_show, NULL), \
> +                 .var = (void *)_config, } \
> +       })[0].attr.attr)
> +
> +static struct attribute *i915_pmu_format_attrs[] = {
> +       I915_PMU_FORMAT_ATTR(i915_eventid, "config:0-42"),
> +       NULL,
> +};
> +
> +static const struct attribute_group i915_pmu_format_attr_group = {
> +       .name = "format",
> +       .attrs = i915_pmu_format_attrs,
> +};
> +
> +static ssize_t i915_pmu_event_show(struct device *dev,
> +                                  struct device_attribute *attr, char *buf)
> +{
> +       struct dev_ext_attribute *eattr;
> +
> +       eattr = container_of(attr, struct dev_ext_attribute, attr);
> +       return sprintf(buf, "config=0x%lx\n", (unsigned long)eattr->var);
> +}
> +
> +#define I915_EVENT_ATTR(_name, _config) \
> +       (&((struct dev_ext_attribute[]) { \
> +               { .attr = __ATTR(_name, 0444, i915_pmu_event_show, NULL), \
> +                 .var = (void *)_config, } \
> +       })[0].attr.attr)
> +
> +#define I915_EVENT_STR(_name, _str) \
> +       (&((struct perf_pmu_events_attr[]) { \
> +               { .attr      = __ATTR(_name, 0444, perf_event_sysfs_show, NULL), \
> +                 .id        = 0, \
> +                 .event_str = _str, } \
> +       })[0].attr.attr)
> +
> +#define I915_EVENT(_name, _config, _unit) \
> +       I915_EVENT_ATTR(_name, _config), \
> +       I915_EVENT_STR(_name.unit, _unit)
> +
> +#define I915_ENGINE_EVENT(_name, _class, _instance, _sample) \
> +       I915_EVENT_ATTR(_name, __I915_PMU_ENGINE(_class, _instance, _sample)), \
> +       I915_EVENT_STR(_name.unit, "ns")
> +
> +#define I915_ENGINE_EVENTS(_name, _class, _instance) \
> +       I915_ENGINE_EVENT(_name##_instance-queued, _class, _instance, I915_SAMPLE_QUEUED), \
> +       I915_ENGINE_EVENT(_name##_instance-busy, _class, _instance, I915_SAMPLE_BUSY), \
> +       I915_ENGINE_EVENT(_name##_instance-sema, _class, _instance, I915_SAMPLE_SEMA), \
> +       I915_ENGINE_EVENT(_name##_instance-wait, _class, _instance, I915_SAMPLE_WAIT)
> +
> +static struct attribute *i915_pmu_events_attrs[] = {
> +       I915_ENGINE_EVENTS(rcs, I915_ENGINE_CLASS_RENDER, 0),
> +       I915_ENGINE_EVENTS(bcs, I915_ENGINE_CLASS_COPY, 0),
> +       I915_ENGINE_EVENTS(vcs, I915_ENGINE_CLASS_VIDEO, 0),
> +       I915_ENGINE_EVENTS(vcs, I915_ENGINE_CLASS_VIDEO, 1),
> +       I915_ENGINE_EVENTS(vecs, I915_ENGINE_CLASS_VIDEO_ENHANCE, 0),

Please add a crossref to intel_engine_cs to remind ourselves to add the
extra perf counters if we add a new engine.

> +
> +       I915_EVENT(actual-frequency,    I915_PMU_ACTUAL_FREQUENCY,    "Hz"),
> +       I915_EVENT(requested-frequency, I915_PMU_REQUESTED_FREQUENCY, "Hz"),
> +
> +       I915_EVENT_ATTR(interrupts, I915_PMU_INTERRUPTS),
> +
> +       I915_EVENT(rc6-residency,   I915_PMU_RC6_RESIDENCY,   "ns"),
> +       I915_EVENT(rc6p-residency,  I915_PMU_RC6p_RESIDENCY,  "ns"),
> +       I915_EVENT(rc6pp-residency, I915_PMU_RC6pp_RESIDENCY, "ns"),
> +
> +       NULL,
> +};
> +
> +static const struct attribute_group i915_pmu_events_attr_group = {
> +       .name = "events",
> +       .attrs = i915_pmu_events_attrs,
> +};
> +
> +static ssize_t
> +i915_pmu_get_attr_cpumask(struct device *dev,
> +                         struct device_attribute *attr,
> +                         char *buf)
> +{
> +       return cpumap_print_to_pagebuf(true, buf, &i915_pmu_cpumask);
> +}
> +
> +static DEVICE_ATTR(cpumask, 0444, i915_pmu_get_attr_cpumask, NULL);
> +
> +static struct attribute *i915_cpumask_attrs[] = {
> +       &dev_attr_cpumask.attr,
> +       NULL,
> +};
> +
> +static struct attribute_group i915_pmu_cpumask_attr_group = {
> +       .attrs = i915_cpumask_attrs,
> +};
> +
> +static const struct attribute_group *i915_pmu_attr_groups[] = {
> +       &i915_pmu_format_attr_group,
> +       &i915_pmu_events_attr_group,
> +       &i915_pmu_cpumask_attr_group,
> +       NULL
> +};
> +
> +static int i915_pmu_cpu_online(unsigned int cpu, struct hlist_node *node)
> +{
> +       unsigned int target;
> +
> +       target = cpumask_any_and(&i915_pmu_cpumask, &i915_pmu_cpumask);
> +       /* Select the first online CPU as a designated reader. */
> +       if (target >= nr_cpu_ids)
> +               cpumask_set_cpu(cpu, &i915_pmu_cpumask);
> +
> +       return 0;
> +}
> +
> +static int i915_pmu_cpu_offline(unsigned int cpu, struct hlist_node *node)
> +{
> +       struct i915_pmu *pmu = hlist_entry_safe(node, typeof(*pmu), node);
> +       unsigned int target;
> +
> +       if (cpumask_test_and_clear_cpu(cpu, &i915_pmu_cpumask)) {
> +               target = cpumask_any_but(topology_sibling_cpumask(cpu), cpu);
> +               /* Migrate events if there is a valid target */
> +               if (target < nr_cpu_ids) {
> +                       cpumask_set_cpu(target, &i915_pmu_cpumask);
> +                       perf_pmu_migrate_context(&pmu->base, cpu, target);
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +void i915_pmu_register(struct drm_i915_private *i915)
> +{
> +       int ret;
> +
> +       if (INTEL_GEN(i915) <= 2) {
> +               DRM_INFO("PMU not supported for this GPU.");
> +               return;
> +       }
> +
> +       ret = cpuhp_setup_state_multi(CPUHP_AP_PERF_X86_UNCORE_ONLINE,
> +                                     "perf/x86/intel/i915:online",
> +                                     i915_pmu_cpu_online,
> +                                     i915_pmu_cpu_offline);
> +       if (ret)
> +               goto err_hp_state;
> +
> +       ret = cpuhp_state_add_instance(CPUHP_AP_PERF_X86_UNCORE_ONLINE,
> +                                      &i915->pmu.node);
> +       if (ret)
> +               goto err_hp_instance;
> +
> +       i915->pmu.base.attr_groups      = i915_pmu_attr_groups;
> +       i915->pmu.base.task_ctx_nr      = perf_invalid_context;
> +       i915->pmu.base.event_init       = i915_pmu_event_init;
> +       i915->pmu.base.add              = i915_pmu_event_add;
> +       i915->pmu.base.del              = i915_pmu_event_del;
> +       i915->pmu.base.start            = i915_pmu_event_start;
> +       i915->pmu.base.stop             = i915_pmu_event_stop;
> +       i915->pmu.base.read             = i915_pmu_event_read;
> +       i915->pmu.base.event_idx        = i915_pmu_event_event_idx;
> +
> +       spin_lock_init(&i915->pmu.lock);
> +       hrtimer_init(&i915->pmu.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +       i915->pmu.timer.function = i915_sample;
> +       i915->pmu.enable = 0;
> +
> +       ret = perf_pmu_register(&i915->pmu.base, "i915", -1);
> +       if (ret == 0)
> +               return;
> +
> +       i915->pmu.base.event_init = NULL;
> +
> +       WARN_ON(cpuhp_state_remove_instance(CPUHP_AP_PERF_X86_UNCORE_ONLINE,
> +                                           &i915->pmu.node));
> +
> +err_hp_instance:
> +       cpuhp_remove_multi_state(CPUHP_AP_PERF_X86_UNCORE_ONLINE);
> +
> +err_hp_state:
> +       DRM_NOTE("Failed to register PMU! (err=%d)\n", ret);

Fair enough, not fatal, the driver will continue; just some user
functionality will be lost. No data loss or anything else meriting a
warning.

> +}
> +
> +void i915_pmu_unregister(struct drm_i915_private *i915)
> +{
> +       if (!i915->pmu.base.event_init)
> +               return;
> +
> +       WARN_ON(cpuhp_state_remove_instance(CPUHP_AP_PERF_X86_UNCORE_ONLINE,
> +                                           &i915->pmu.node));
> +       cpuhp_remove_multi_state(CPUHP_AP_PERF_X86_UNCORE_ONLINE);
> +
> +       i915->pmu.enable = 0;
> +
> +       hrtimer_cancel(&i915->pmu.timer);
> +
> +       perf_pmu_unregister(&i915->pmu.base);
> +       i915->pmu.base.event_init = NULL;
> +}
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 82f36dd0cd94..16e36b2eef87 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -186,6 +186,9 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
>  #define VIDEO_ENHANCEMENT_CLASS        2
>  #define COPY_ENGINE_CLASS      3
>  #define OTHER_CLASS            4
> +#define MAX_ENGINE_CLASS       4
> +
> +#define MAX_ENGINE_INSTANCE    1
>  
>  /* PCI config space */
>  
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index a28e2a864cf1..35c117c3fa0d 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -200,6 +200,15 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
>         GEM_BUG_ON(info->class >= ARRAY_SIZE(intel_engine_classes));
>         class_info = &intel_engine_classes[info->class];
>  
> +       if (GEM_WARN_ON(info->class > MAX_ENGINE_CLASS))
> +               return -EINVAL;
> +
> +       if (GEM_WARN_ON(info->instance > MAX_ENGINE_INSTANCE))
> +               return -EINVAL;
> +
> +       if (GEM_WARN_ON(dev_priv->engine_class[info->class][info->instance]))
> +               return -EINVAL;
> +
>         GEM_BUG_ON(dev_priv->engine[id]);
>         engine = kzalloc(sizeof(*engine), GFP_KERNEL);
>         if (!engine)
> @@ -227,6 +236,7 @@ intel_engine_setup(struct drm_i915_private *dev_priv,
>  
>         ATOMIC_INIT_NOTIFIER_HEAD(&engine->context_status_notifier);
>  
> +       dev_priv->engine_class[info->class][info->instance] = engine;
>         dev_priv->engine[id] = engine;
>         return 0;
>  }
> @@ -1578,6 +1588,31 @@ bool intel_engine_can_store_dword(struct intel_engine_cs *engine)
>         }
>  }
>  
> +static u8 user_class_map[I915_ENGINE_CLASS_MAX] = {
> +       [I915_ENGINE_CLASS_OTHER] = OTHER_CLASS,
> +       [I915_ENGINE_CLASS_RENDER] = RENDER_CLASS,
> +       [I915_ENGINE_CLASS_COPY] = COPY_ENGINE_CLASS,
> +       [I915_ENGINE_CLASS_VIDEO] = VIDEO_DECODE_CLASS,
> +       [I915_ENGINE_CLASS_VIDEO_ENHANCE] = VIDEO_ENHANCEMENT_CLASS,
> +};
> +
> +struct intel_engine_cs *
> +intel_engine_lookup_user(struct drm_i915_private *i915, u8 class, u8 instance)
> +{
> +       if (class >= ARRAY_SIZE(user_class_map))
> +               return NULL;
> +
> +       class = user_class_map[class];
> +
> +       if (WARN_ON_ONCE(class > MAX_ENGINE_CLASS))
> +               return NULL;
> +
> +       if (instance > MAX_ENGINE_INSTANCE)
> +               return NULL;
> +
> +       return i915->engine_class[class][instance];
> +}
> +
>  #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>  #include "selftests/mock_engine.c"
>  #endif
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index 56d7ae9f298b..7a901e766d03 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -330,6 +330,28 @@ struct intel_engine_cs {
>                 I915_SELFTEST_DECLARE(bool mock : 1);
>         } breadcrumbs;
>  
> +       struct {
> +               /**
> +                * @enable: Bitmask of enable sample events on this engine.
> +                *
> +                * Bits correspond to sample event types, for instance
> +                * I915_SAMPLE_QUEUED is bit 0 etc.
> +                */
> +               u32 enable;
> +               /**
> +                * @enable_count: Reference count for the enabled samplers.
> +                *
> +                * Index number corresponds to the bit number from @enable.
> +                */
> +               unsigned int enable_count[I915_PMU_SAMPLE_BITS];
> +               /**
> +                * @sample: Counter value for sampling events.
> +                *
> +                * Our internal timer stores the current counter in this field.
> +                */
> +               u64 sample[I915_ENGINE_SAMPLE_MAX];
> +       } pmu;
> +
>         /*
>          * A pool of objects to use as shadow copies of client batch buffers
>          * when the command parser is enabled. Prevents the client from
> @@ -834,4 +856,7 @@ void intel_engines_reset_default_submission(struct drm_i915_private *i915);
>  
>  bool intel_engine_can_store_dword(struct intel_engine_cs *engine);
>  
> +struct intel_engine_cs *
> +intel_engine_lookup_user(struct drm_i915_private *i915, u8 class, u8 instance);
> +
>  #endif /* _INTEL_RINGBUFFER_H_ */
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index fe25a01c81f2..682abafecc8c 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -86,6 +86,63 @@ enum i915_mocs_table_index {
>         I915_MOCS_CACHED,
>  };

Hmm, how about uapi/drm/i915_perf.h? (Or i915_pmu.h)
We are not adding traditional drm-ioctl functionality (except for some
common enums). But I guess it is not huge, so no big concern. Just
thinking that we essentially copy this into igt, so we should really
make it a copy!

> +enum drm_i915_gem_engine_class {
> +       I915_ENGINE_CLASS_OTHER = 0,
> +       I915_ENGINE_CLASS_RENDER = 1,
> +       I915_ENGINE_CLASS_COPY = 2,
> +       I915_ENGINE_CLASS_VIDEO = 3,
> +       I915_ENGINE_CLASS_VIDEO_ENHANCE = 4,
> +       I915_ENGINE_CLASS_MAX /* non-ABI */
> +};
> +
> +/**
> + * DOC: perf_events exposed by i915 through /sys/bus/event_sources/drivers/i915
> + *
> + */
> +
> +enum drm_i915_pmu_engine_sample {
> +       I915_SAMPLE_QUEUED = 0,
> +       I915_SAMPLE_BUSY = 1,
> +       I915_SAMPLE_WAIT = 2,
> +       I915_SAMPLE_SEMA = 3,
> +       I915_ENGINE_SAMPLE_MAX /* non-ABI */
> +};
> +
> +#define I915_PMU_SAMPLE_BITS (4)
> +#define I915_PMU_SAMPLE_MASK (0xf)
> +#define I915_PMU_SAMPLE_INSTANCE_BITS (8)
> +#define I915_PMU_CLASS_SHIFT \
> +       (I915_PMU_SAMPLE_BITS + I915_PMU_SAMPLE_INSTANCE_BITS)
> +
> +#define __I915_PMU_ENGINE(class, instance, sample) \
> +       ((class) << I915_PMU_CLASS_SHIFT | \
> +       (instance) << I915_PMU_SAMPLE_BITS | \
> +       (sample))
> +
> +#define I915_PMU_ENGINE_QUEUED(class, instance) \
> +       __I915_PMU_ENGINE(class, instance, I915_SAMPLE_QUEUED)
> +
> +#define I915_PMU_ENGINE_BUSY(class, instance) \
> +       __I915_PMU_ENGINE(class, instance, I915_SAMPLE_BUSY)
> +
> +#define I915_PMU_ENGINE_WAIT(class, instance) \
> +       __I915_PMU_ENGINE(class, instance, I915_SAMPLE_WAIT)
> +
> +#define I915_PMU_ENGINE_SEMA(class, instance) \
> +       __I915_PMU_ENGINE(class, instance, I915_SAMPLE_SEMA)
> +
> +#define __I915_PMU_OTHER(x) (__I915_PMU_ENGINE(0xff, 0xff, 0xf) + 1 + (x))
> +
> +#define I915_PMU_ACTUAL_FREQUENCY      __I915_PMU_OTHER(0)
> +#define I915_PMU_REQUESTED_FREQUENCY   __I915_PMU_OTHER(1)
> +#define I915_PMU_INTERRUPTS            __I915_PMU_OTHER(2)
> +
> +#define I915_PMU_RC6_RESIDENCY         __I915_PMU_OTHER(3)
> +#define I915_PMU_RC6p_RESIDENCY                __I915_PMU_OTHER(4)
> +#define I915_PMU_RC6pp_RESIDENCY       __I915_PMU_OTHER(5)
> +
> +#define I915_PMU_LAST I915_PMU_RC6pp_RESIDENCY
> +
>  /* Each region is a minimum of 16k, and there are at most 255 of them.
>   */
>  #define I915_NR_TEX_REGIONS 255        /* table size 2k - maximum due to use
> -- 
> 2.9.5
> 
> 
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