[PATCH 2/3] drm/amd/amdgpu: Define and implement a function that collects number of waves that are in flight.

* [PATCH 2/3] drm/amd/amdgpu: Define and implement a function that collects number of waves that are in flight.
@ 2020-09-17 17:10 Ramesh Errabolu
  0 siblings, 0 replies; 3+ messages in thread
From: Ramesh Errabolu @ 2020-09-17 17:10 UTC (permalink / raw)
  To: amd-gfx; +Cc: Ramesh Errabolu

[Why]
Allow user to know how many compute units (CU) are in use at any given
moment.

[How]
Read registers of SQ that give number of waves that are in flight
of various queues. Use this information to determine number of CU's
in use.

Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu@amd.com>
---
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c | 206 ++++++++++++++++++
 .../gpu/drm/amd/include/kgd_kfd_interface.h   |  11 +
 2 files changed, 217 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c
index e6aede725197..2f8c8140734e 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c
@@ -38,7 +38,9 @@
 #include "soc15d.h"
 #include "mmhub_v1_0.h"
 #include "gfxhub_v1_0.h"
+#include "gfx_v9_0.h"
 
+struct kfd_dev;
 
 enum hqd_dequeue_request_type {
 	NO_ACTION = 0,
@@ -706,6 +708,209 @@ void kgd_gfx_v9_set_vm_context_page_table_base(struct kgd_dev *kgd,
 	gfxhub_v1_0_setup_vm_pt_regs(adev, vmid, page_table_base);
 }
 
+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 particulare queue. The method also returns the VMID 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
+ *
+ * @wave_cnt: Output parameter updated with number of waves in flight
+ *
+ * @vmid: Output parameter updated with VMID of queue whose wave count
+ * is being collected
+ */
+static void get_wave_count(struct amdgpu_device *adev, int queue_idx,
+			   int *wave_cnt, int *vmid)
+{
+	int pipe_idx;
+	int queue_slot;
+	unsigned int reg_val;
+
+	/*
+	 * By policy queues at slots 0 and 1 are reserved for non-compute
+	 * queues i.e. those managed for graphic functions.
+	 */
+	if ((queue_idx % adev->gfx.mec.num_queue_per_pipe) < 2)
+		return;
+
+	/*
+	 * Queue belongs to a compute workload. Determine the PIPE index
+	 * associated wit queue and program GRBM accordingly:
+	 * MEID = 1, PIPEID = pipe_idx, QUEUEID = queue_idx, VMID = 0
+	 */
+	pipe_idx = queue_idx / adev->gfx.mec.num_queue_per_pipe;
+	queue_slot = queue_idx % adev->gfx.mec.num_queue_per_pipe;
+	soc15_grbm_select(adev, 1, pipe_idx, queue_slot, 0);
+
+	/*
+	 * Read from register number of waves in flight. If non-zero get the
+	 * VMID associated with queue
+	 */
+	reg_val = RREG32(SOC15_REG_OFFSET(GC, 0, mmSPI_CSQ_WF_ACTIVE_COUNT_0) +
+			 queue_slot);
+	*wave_cnt = reg_val & SPI_CSQ_WF_ACTIVE_COUNT_0__COUNT_MASK;
+	if (*wave_cnt != 0)
+		*vmid = (RREG32_SOC15(GC, 0, mmCP_HQD_VMID) &
+			 CP_HQD_VMID__VMID_MASK) >> CP_HQD_VMID__VMID__SHIFT;
+}
+
+/**
+ * @kgd_gfx_v9_get_cu_occupancy: Reads relevant registers associated with each
+ * shader engine and aggregates the number of waves that are in fight 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.
+ *
+ * @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 in accurate 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.
+ *
+ * @kgd: Handle of device from which to get number of waves in flight
+ *
+ * @pasid: Identifies the process for which this query call is invoked
+ *
+ * @wave_cnt: Output parameter updated with number of waves in flight that
+ * belong to process with given pasid
+ *
+ * The registers that provide the waves in flight are:
+ *
+ *  SPI_CSQ_WF_ACTIVE_STATUS - bit-map of queues per pipe. At any moment there
+ *  can be a max of 32 queues that could submit wave fronts to be run by compute
+ *  units. The bit is ON if a queue is slotted, OFF if there is no queue. The
+ *  process could have ZERO or more queues slotted and submitting waves to be
+ *  run 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 fligth, read CP_HQD_VMID register to obtain VMID
+ *    of the wave(s).
+ *
+ *    Determine if VMID from above step maps to pasid provided as parameter. If
+ *    it matches agrregate the wave count. That the VMID will not match pasid is
+ *    a normal condition i.e. a device is expected to support multiple queues
+ *    from multiple proceses.
+ *
+ *  @note: Reading the registers mentioned above requires programming GRBM
+ *  appropriately.
+ */
+static void kgd_gfx_v9_get_cu_occupancy(struct kgd_dev *kgd, int pasid,
+					int *pasid_wave_cnt)
+{
+	int qidx;
+	int vmid;
+	int se_idx;
+	int sh_idx;
+	int se_cnt;
+	int sh_cnt;
+	int wave_cnt;
+	int queue_map;
+	int pasid_tmp;
+	int vmid_wave_cnt = 0;
+	struct amdgpu_device *adev;
+	DECLARE_BITMAP(cp_queue_bitmap, KGD_MAX_QUEUES);
+
+	/*
+	 * Acquire  SRBM/GRBM locks before programming them to read registers.
+	 * By policy compute workloads are submitted on MEC1 (Micro-Engine)
+	 * Program GRBM to allow reading registers from MEC1. This constitutes
+	 * base programming. Programming of bit-fields for PIPE, QUEUE, etc will
+	 * be done later
+	 */
+	adev = get_amdgpu_device(kgd);
+	lock_spi_csq_mutexes(adev);
+	soc15_grbm_select(adev, 1, 0, 0, 0);
+
+	/*
+	 * Iterate through the shader engines and arrays of the device
+	 * to read registers that provide number of waves in flight
+	 */
+	bitmap_complement(cp_queue_bitmap, adev->gfx.mec.queue_bitmap,
+			  KGD_MAX_QUEUES);
+	sh_cnt = adev->gfx.config.max_sh_per_se;
+	se_cnt = adev->gfx.config.max_shader_engines;
+	for (se_idx = 0; se_idx < se_cnt; se_idx++) {
+		for (sh_idx = 0; sh_idx < sh_cnt; sh_idx++) {
+
+			/*
+			 * Program GRBM to read queue map register that is
+			 * associated with specified shader engine and array
+			 */
+			gfx_v9_0_select_se_sh(adev, se_idx, sh_idx, 0xffffffff);
+			queue_map = RREG32(SOC15_REG_OFFSET(GC, 0,
+					   mmSPI_CSQ_WF_ACTIVE_STATUS));
+
+			/*
+			 * Assumption: queue map encodes following schema: four
+			 * pipes per each micro-engine, with each pipe mapping
+			 * eight queues. This schema is true for GFX9 devices
+			 * and must be verified for newer device families
+			 */
+			for (qidx = 0; qidx < 32; qidx++) {
+				if (!test_bit(qidx, cp_queue_bitmap))
+					continue;
+				if (!(queue_map & (1 << qidx)))
+					continue;
+
+				/*
+				 * For the specified queue index read number of
+				 * waves in flight and the VMID of the waves
+				 */
+				vmid = 0xFF;
+				wave_cnt = 0;
+				get_wave_count(adev, qidx, &wave_cnt, &vmid);
+
+				/*
+				 * Get PASID that is associated with VMID and
+				 * update the waves-in-flight aggregate
+				 */
+				if (wave_cnt != 0) {
+					pasid_tmp =
+					  RREG32(SOC15_REG_OFFSET(OSSSYS, 0,
+						 mmIH_VMID_0_LUT) + vmid);
+					if (pasid_tmp == pasid)
+						vmid_wave_cnt += wave_cnt;
+				}
+			}
+		}
+	}
+
+	/*
+	 * Reset GRBM to default state before releasing locks
+	 * associated with GRBM/SRBM resources
+	 */
+	gfx_v9_0_select_se_sh(adev, 0xffffffff, 0xffffffff, 0xffffffff);
+	soc15_grbm_select(adev, 0, 0, 0, 0);
+	unlock_spi_csq_mutexes(adev);
+
+	/* Update the output parameter and return */
+	*pasid_wave_cnt = vmid_wave_cnt;
+}
+
 const struct kfd2kgd_calls gfx_v9_kfd2kgd = {
 	.program_sh_mem_settings = kgd_gfx_v9_program_sh_mem_settings,
 	.set_pasid_vmid_mapping = kgd_gfx_v9_set_pasid_vmid_mapping,
@@ -726,4 +931,5 @@ const struct kfd2kgd_calls gfx_v9_kfd2kgd = {
 	.get_atc_vmid_pasid_mapping_info =
 			kgd_gfx_v9_get_atc_vmid_pasid_mapping_info,
 	.set_vm_context_page_table_base = kgd_gfx_v9_set_vm_context_page_table_base,
+	.get_cu_occupancy = kgd_gfx_v9_get_cu_occupancy,
 };
diff --git a/drivers/gpu/drm/amd/include/kgd_kfd_interface.h b/drivers/gpu/drm/amd/include/kgd_kfd_interface.h
index fc592f60e6a0..19e885cd0853 100644
--- a/drivers/gpu/drm/amd/include/kgd_kfd_interface.h
+++ b/drivers/gpu/drm/amd/include/kgd_kfd_interface.h
@@ -212,6 +212,15 @@ struct tile_config {
  * IH ring entry. This function allows the KFD ISR to get the VMID
  * from the fault status register as early as possible.
  *
+ * @get_cu_occupancy: Function pointer that returns to caller the number
+ * of wave fronts that are in flight for all of the queues of a process
+ * as identified by its pasid. It is important to note that the value
+ * returned by this function is a snapshot of current moment and cannot
+ * guarantee any minimum for the number of waves in-flight. This function
+ * is defined for devices that belong to GFX9 and later GFX families. Care
+ * must be taken in calling this function as it is not defined for devices
+ * that belong to GFX8 and below GFX families.
+ *
  * This structure contains function pointers to services that the kgd driver
  * provides to amdkfd driver.
  *
@@ -286,6 +295,8 @@ struct kfd2kgd_calls {
 	void (*set_vm_context_page_table_base)(struct kgd_dev *kgd,
 			uint32_t vmid, uint64_t page_table_base);
 	uint32_t (*read_vmid_from_vmfault_reg)(struct kgd_dev *kgd);
+
+	void (*get_cu_occupancy)(struct kgd_dev *kgd, int pasid, int *wave_cnt);
 };
 
 #endif	/* KGD_KFD_INTERFACE_H_INCLUDED */
-- 
2.27.0

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