Re: [PATCH 1/2] drm/kfd: Add CU occupancy support to GFX11

On Mon, Aug 17, 2026 at 4:45 PM David Belanger <[email protected]> wrote:
>
> Port changes from GFX9 to GFX11 mostly as-is.
> Minor changes to register access code.

While you are at it, can you port this to gfx10 10 and 10.3 as well?

>
> Assisted-by: Claude:Sonnet 4.6
> Signed-off-by: David Belanger <[email protected]>
> ---
>  .../drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c    | 148 ++++++++++++++++++
>  1 file changed, 148 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c
> index 724beb96ed1aa..46042f72741b4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v11.c
> @@ -807,6 +807,153 @@ static uint32_t kgd_gfx_v11_hqd_sdma_get_doorbell(struct amdgpu_device *adev,
>         return 0;
>  }
>
> +static void lock_spi_csq_mutexes(struct amdgpu_device *adev)
> +{
> +       mutex_lock(&adev->srbm_mutex);
> +       mutex_lock(&adev->grbm_idx_mutex);
> +
> +}
> +
> +static void unlock_spi_csq_mutexes(struct amdgpu_device *adev)
> +{
> +       mutex_unlock(&adev->grbm_idx_mutex);
> +       mutex_unlock(&adev->srbm_mutex);
> +}
> +
> +/**
> + * get_wave_count: Read device registers to get number of waves in flight for
> + * a particular queue. The method also returns the doorbell offset associated
> + * with the queue.
> + *
> + * @adev: Handle of device whose registers are to be read
> + * @queue_idx: Index of queue in the queue-map bit-field
> + * @queue_cnt: Stores the wave count and doorbell offset for an active queue
> + * @inst: xcc's instance number on a multi-XCC setup
> + */
> +static void get_wave_count(struct amdgpu_device *adev, int queue_idx,
> +               struct kfd_cu_occupancy *queue_cnt, uint32_t inst)
> +{
> +       int pipe_idx;
> +       int queue_slot;
> +       unsigned int reg_val;
> +       unsigned int wave_cnt;
> +       /*
> +        * Program GRBM with appropriate MEID, PIPEID, QUEUEID and VMID
> +        * parameters to read out waves in flight. Get VMID if there are
> +        * non-zero waves in flight.
> +        */
> +       pipe_idx = queue_idx / adev->gfx.mec.num_queue_per_pipe;
> +       queue_slot = queue_idx % adev->gfx.mec.num_queue_per_pipe;
> +       soc21_grbm_select(adev, 1, pipe_idx, queue_slot, 0);
> +       reg_val = RREG32_SOC15_IP(GC, SOC15_REG_OFFSET(GC, 0,
> +                                 regSPI_CSQ_WF_ACTIVE_COUNT_0) + queue_slot);
> +       wave_cnt = reg_val & SPI_CSQ_WF_ACTIVE_COUNT_0__COUNT_MASK;
> +       if (wave_cnt != 0) {
> +               queue_cnt->wave_cnt += wave_cnt;
> +               queue_cnt->doorbell_off =
> +                       (RREG32_SOC15(GC, 0, regCP_HQD_PQ_DOORBELL_CONTROL) &
> +                        CP_HQD_PQ_DOORBELL_CONTROL__DOORBELL_OFFSET_MASK) >>
> +                        CP_HQD_PQ_DOORBELL_CONTROL__DOORBELL_OFFSET__SHIFT;
> +       }
> +}
> +
> +/**
> + * kgd_gfx_v11_get_cu_occupancy: Reads relevant registers associated with each
> + * shader engine and aggregates the number of waves that are in flight for the
> + * process whose pasid is provided as a parameter. The process could have ZERO
> + * or more queues running and submitting waves to compute units.
> + *
> + * @adev: Handle of device from which to get number of waves in flight
> + * @cu_occupancy: Array that gets filled with wave_cnt and doorbell offset
> + *               for comparison later.
> + * @max_waves_per_cu: Output parameter updated with maximum number of waves
> + *                    possible per Compute Unit
> + * @inst: xcc's instance number on a multi-XCC setup
> + *
> + * Note: It's possible that the device has too many queues (oversubscription)
> + * in which case a VMID could be remapped to a different PASID. This could lead
> + * to an inaccurate wave count. Following is a high-level sequence:
> + *    Time T1: vmid = getVmid(); vmid is associated with Pasid P1
> + *    Time T2: passId = getPasId(vmid); vmid is associated with Pasid P2
> + * In the sequence above wave count obtained from time T1 will be incorrectly
> + * lost or added to total wave count.
> + *
> + * The registers that provide the waves in flight are:
> + *
> + *  SPI_CSQ_WF_ACTIVE_STATUS - bit-map of queues per pipe. The bit is ON if a
> + *  queue is slotted, OFF if there is no queue. A process could have ZERO or
> + *  more queues slotted and submitting waves to be run on compute units. Even
> + *  when there is a queue it is possible there could be zero wave fronts, this
> + *  can happen when queue is waiting on top-of-pipe events - e.g. waitRegMem
> + *  command
> + *
> + *  For each bit that is ON from above:
> + *
> + *    Read (SPI_CSQ_WF_ACTIVE_COUNT_0 + queue_idx) register. It provides the
> + *    number of waves that are in flight for the queue at specified index. The
> + *    index ranges from 0 to 7.
> + *
> + *    If non-zero waves are in flight, store the corresponding doorbell offset
> + *    of the queue, along with the wave count.
> + *
> + *    Determine if the queue belongs to the process by comparing the doorbell
> + *    offset against the process's queues. If it matches, aggregate the wave
> + *    count for the process.
> + *
> + *  Reading registers referenced above involves programming GRBM appropriately
> + */
> +static void kgd_gfx_v11_get_cu_occupancy(struct amdgpu_device *adev,
> +                               struct kfd_cu_occupancy *cu_occupancy,
> +                               int *max_waves_per_cu, uint32_t inst)
> +{
> +       int qidx;
> +       int se_idx;
> +       int se_cnt;
> +       int queue_map;
> +       int max_queue_cnt;
> +       DECLARE_BITMAP(cp_queue_bitmap, AMDGPU_MAX_QUEUES);
> +
> +       lock_spi_csq_mutexes(adev);
> +       soc21_grbm_select(adev, 1, 0, 0, 0);
> +
> +       /*
> +        * Iterate through the shader engines and arrays of the device
> +        * to get number of waves in flight
> +        */
> +       bitmap_complement(cp_queue_bitmap, adev->gfx.mec_bitmap[0].queue_bitmap,
> +                         AMDGPU_MAX_QUEUES);
> +       max_queue_cnt = adev->gfx.mec.num_pipe_per_mec *
> +                       adev->gfx.mec.num_queue_per_pipe;
> +       se_cnt = adev->gfx.config.max_shader_engines;
> +       for (se_idx = 0; se_idx < se_cnt; se_idx++) {
> +               amdgpu_gfx_select_se_sh(adev, se_idx, 0, 0xffffffff, inst);
> +               queue_map = RREG32_SOC15(GC, 0,
> +                                        regSPI_CSQ_WF_ACTIVE_STATUS);
> +
> +               for (qidx = 0; qidx < max_queue_cnt; qidx++) {
> +                       /* Skip queues that are not associated with
> +                        * compute functions
> +                        */
> +                       if (!test_bit(qidx, cp_queue_bitmap))
> +                               continue;
> +
> +                       if (!(queue_map & (1 << qidx)))
> +                               continue;
> +
> +                       /* Get number of waves in flight and aggregate them */
> +                       get_wave_count(adev, qidx, &cu_occupancy[qidx], inst);
> +               }
> +       }
> +
> +       amdgpu_gfx_select_se_sh(adev, 0xffffffff, 0xffffffff, 0xffffffff, inst);
> +       soc21_grbm_select(adev, 0, 0, 0, 0);
> +       unlock_spi_csq_mutexes(adev);
> +

I think you need to disallow gfxoff around the MMIO accesses unless
that is already handled elsewhere.  Same comment on the gfx12
implementation.

Alex

> +       /* Update the output parameters and return */
> +       *max_waves_per_cu = adev->gfx.cu_info.simd_per_cu *
> +                               adev->gfx.cu_info.max_waves_per_simd;
> +}
> +
>  const struct kfd2kgd_calls gfx_v11_kfd2kgd = {
>         .program_sh_mem_settings = program_sh_mem_settings_v11,
>         .set_pasid_vmid_mapping = set_pasid_vmid_mapping_v11,
> @@ -832,5 +979,6 @@ const struct kfd2kgd_calls gfx_v11_kfd2kgd = {
>         .clear_address_watch = kgd_gfx_v11_clear_address_watch,
>         .hqd_get_pq_addr = kgd_gfx_v11_hqd_get_pq_addr,
>         .hqd_reset = kgd_gfx_v11_hqd_reset,
> +       .get_cu_occupancy = kgd_gfx_v11_get_cu_occupancy,
>         .hqd_sdma_get_doorbell = kgd_gfx_v11_hqd_sdma_get_doorbell
>  };
> --
> 2.51.1
>