Re: [PATCH v3 06/11] drm/xe/multi_queue: Add helpers to access CS QUEUE TIMESTAMP from lrc

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

On Tue, May 05, 2026 at 04:44:15PM -0700, Umesh Nerlige Ramappa wrote:
>In secondary queue LRCs, the QUEUE TIMESTAMP register is saved and
>restored allowing us to view the individual queue run times. Add helpers
>to read this value from the LRC.
>
>BSpec: 73988
>
>Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>---
>v2: (Matt)
>- Add BSpec reference
>- Make queue_timestamp snapshot 64 bit
>- Add a snapshot of queue timestamp in ms
>
>v3:
>- Replace xe_lrc_is_multi_queue check in lrc init (Niranajana)
>- Use assert instead of check in xe_lrc_queue_timestamp
>---
> drivers/gpu/drm/xe/regs/xe_lrc_layout.h |  3 ++
> drivers/gpu/drm/xe/xe_lrc.c             | 46 +++++++++++++++++++++++++
> drivers/gpu/drm/xe/xe_lrc.h             |  2 ++
> drivers/gpu/drm/xe/xe_lrc_types.h       |  3 ++
> 4 files changed, 54 insertions(+)
>
>diff --git a/drivers/gpu/drm/xe/regs/xe_lrc_layout.h b/drivers/gpu/drm/xe/regs/xe_lrc_layout.h
>index b5eff383902c..4ab86fc369fd 100644
>--- a/drivers/gpu/drm/xe/regs/xe_lrc_layout.h
>+++ b/drivers/gpu/drm/xe/regs/xe_lrc_layout.h
>@@ -34,6 +34,9 @@
> #define CTX_CS_INT_VEC_REG		0x5a
> #define CTX_CS_INT_VEC_DATA		(CTX_CS_INT_VEC_REG + 1)
>
>+#define CTX_QUEUE_TIMESTAMP		(0xd0 + 1)
>+#define CTX_QUEUE_TIMESTAMP_UDW		(0xd2 + 1)
>+
> #define INDIRECT_CTX_RING_HEAD		(0x02 + 1)
> #define INDIRECT_CTX_RING_TAIL		(0x04 + 1)
> #define INDIRECT_CTX_RING_START		(0x06 + 1)
>diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
>index 3b6990d68a5a..127a2ebc3679 100644
>--- a/drivers/gpu/drm/xe/xe_lrc.c
>+++ b/drivers/gpu/drm/xe/xe_lrc.c
>@@ -777,6 +777,16 @@ static u32 __xe_lrc_ctx_timestamp_udw_offset(struct xe_lrc *lrc)
> 	return __xe_lrc_regs_offset(lrc) + CTX_TIMESTAMP_UDW * sizeof(u32);
> }
>
>+static u32 __xe_lrc_queue_timestamp_offset(struct xe_lrc *lrc)
>+{
>+	return __xe_lrc_regs_offset(lrc) + CTX_QUEUE_TIMESTAMP * sizeof(u32);
>+}
>+
>+static u32 __xe_lrc_queue_timestamp_udw_offset(struct xe_lrc *lrc)
>+{
>+	return __xe_lrc_regs_offset(lrc) + CTX_QUEUE_TIMESTAMP_UDW * sizeof(u32);
>+}
>+
> static inline u32 __xe_lrc_indirect_ring_offset(struct xe_lrc *lrc)
> {
> 	u32 offset = xe_bo_size(lrc->bo) - LRC_WA_BB_SIZE -
>@@ -826,6 +836,8 @@ DECL_MAP_ADDR_HELPERS(ctx_timestamp_udw, lrc->bo)
> DECL_MAP_ADDR_HELPERS(parallel, lrc->bo)
> DECL_MAP_ADDR_HELPERS(indirect_ring, lrc->bo)
> DECL_MAP_ADDR_HELPERS(engine_id, lrc->bo)
>+DECL_MAP_ADDR_HELPERS(queue_timestamp, lrc->bo)
>+DECL_MAP_ADDR_HELPERS(queue_timestamp_udw, lrc->bo)
>
> #undef DECL_MAP_ADDR_HELPERS
>
>@@ -874,6 +886,29 @@ static u64 xe_lrc_ctx_timestamp(struct xe_lrc *lrc)
> 	return (u64)udw << 32 | ldw;
> }
>
>+/**
>+ * xe_lrc_queue_timestamp() - Read queue timestamp value
>+ * @lrc: Pointer to the lrc.
>+ *
>+ * Returns: queue timestamp value
>+ */
>+static u64 xe_lrc_queue_timestamp(struct xe_lrc *lrc)
>+{
>+	struct xe_device *xe = lrc_to_xe(lrc);
>+	struct iosys_map map;
>+	u32 ldw, udw = 0;
>+
>+	xe_assert(xe, xe_lrc_is_multi_queue(lrc));
>+
>+	map = __xe_lrc_queue_timestamp_map(lrc);
>+	ldw = xe_map_read32(xe, &map);
>+
>+	map = __xe_lrc_queue_timestamp_udw_map(lrc);
>+	udw = xe_map_read32(xe, &map);
>+
>+	return (u64)udw << 32 | ldw;
>+}
>+
> /**
>  * xe_lrc_ctx_job_timestamp_ggtt_addr() - Get ctx job timestamp GGTT address
>  * @lrc: Pointer to the lrc.
>@@ -1538,6 +1573,12 @@ static int xe_lrc_ctx_init(struct xe_lrc *lrc, struct xe_hw_engine *hwe, struct
> 	if (lrc_to_xe(lrc)->info.has_64bit_timestamp)
> 		xe_lrc_write_ctx_reg(lrc, CTX_TIMESTAMP_UDW, 0);
>
>+	if (xe_gt_hwe_class_supports_multi_queue(gt, hwe->class)) {
>+		lrc->queue_timestamp = 0;
>+		xe_lrc_write_ctx_reg(lrc, CTX_QUEUE_TIMESTAMP, 0);
>+		xe_lrc_write_ctx_reg(lrc, CTX_QUEUE_TIMESTAMP_UDW, 0);
>+	}

xe_gt_hwe_class_supports_multi_queue() doesn't mean given 'lrc' is multi-queue.
The 'lrc' is multi-queue only if xe_gt_hwe_class_supports_multi_queue() is true
and user has opened that exec queue as a multi-queue.

But yah, we don't know whether the given 'lrc' is a multi-queue lrc here.
Perhaps, it is ok to keep this code as is, as it doesn't hurt. May be add
a comment above explaining it.

>+
> 	if (xe->info.has_asid && vm)
> 		xe_lrc_write_ctx_reg(lrc, CTX_ASID, vm->usm.asid);
>
>@@ -2466,6 +2507,9 @@ struct xe_lrc_snapshot *xe_lrc_snapshot_capture(struct xe_lrc *lrc)
> 	snapshot->ctx_timestamp = xe_lrc_ctx_timestamp(lrc);
> 	snapshot->ctx_timestamp_ms =
> 		xe_gt_clock_interval_to_ms(lrc->gt, xe_lrc_ctx_timestamp(lrc));
>+	snapshot->queue_timestamp = xe_lrc_queue_timestamp(lrc);
>+	snapshot->queue_timestamp_ms =
>+		xe_gt_clock_interval_to_ms(lrc->gt, xe_lrc_queue_timestamp(lrc));

queue_timestamp is only supported if lrc is multi-queue.
As we are calling this for all cases here, xe_lrc_queue_timestamp() will assert.

I think we should do,
if (xe_lrc_is_multi_queue(lrc)) {
    snapshot->queue_timestamp = ...;
    snapshot->queue_timestamp_ms = ...;
} else {
    snapshot->queue_timestamp = 0
    snapshot->queue_timestamp_ms = 0
}

Niranjana

> 	snapshot->ctx_job_timestamp = xe_lrc_ctx_job_timestamp(lrc);
> 	return snapshot;
> }
>@@ -2520,6 +2564,8 @@ void xe_lrc_snapshot_print(struct xe_lrc_snapshot *snapshot, struct drm_printer
> 	drm_printf(p, "\tSeqno: (memory) %d\n", snapshot->seqno);
> 	drm_printf(p, "\tTimestamp: 0x%016llx\n", snapshot->ctx_timestamp);
> 	drm_printf(p, "\tTimestamp ms: %llu\n", snapshot->ctx_timestamp_ms);
>+	drm_printf(p, "\tQueue Timestamp: 0x%016llx\n", snapshot->queue_timestamp);
>+	drm_printf(p, "\tQueue Timestamp ms: %llu\n", snapshot->queue_timestamp_ms);
> 	drm_printf(p, "\tJob Timestamp: 0x%08x\n", snapshot->ctx_job_timestamp);
>
> 	if (!snapshot->lrc_snapshot)
>diff --git a/drivers/gpu/drm/xe/xe_lrc.h b/drivers/gpu/drm/xe/xe_lrc.h
>index 557dce004d48..0a3a611391ee 100644
>--- a/drivers/gpu/drm/xe/xe_lrc.h
>+++ b/drivers/gpu/drm/xe/xe_lrc.h
>@@ -39,6 +39,8 @@ struct xe_lrc_snapshot {
> 	u32 seqno;
> 	u64 ctx_timestamp;
> 	u64 ctx_timestamp_ms;
>+	u64 queue_timestamp;
>+	u64 queue_timestamp_ms;
> 	u32 ctx_job_timestamp;
> };
>
>diff --git a/drivers/gpu/drm/xe/xe_lrc_types.h b/drivers/gpu/drm/xe/xe_lrc_types.h
>index 0a5c13ec2ad7..53ef48feebfc 100644
>--- a/drivers/gpu/drm/xe/xe_lrc_types.h
>+++ b/drivers/gpu/drm/xe/xe_lrc_types.h
>@@ -64,6 +64,9 @@ struct xe_lrc {
> 	/** @ctx_timestamp: readout value of CTX_TIMESTAMP on last update */
> 	u64 ctx_timestamp;
>
>+	/** @queue_timestamp: value of QUEUE_TIMESTAMP on last update */
>+	u64 queue_timestamp;
>+
> 	/** @multi_queue: Multi queue LRC related information */
> 	struct {
> 		/** @multi_queue.primary_lrc: Primary lrc of this multi-queue group*/
>-- 
>2.51.0
>