Re: [PATCH] drm/xe/oa/uapi: Expose an unblock after N reports OA property

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

On Thu, Dec 12, 2024 at 02:49:03PM -0800, Ashutosh Dixit wrote:
>Expose an "unblock after N reports" OA property, to allow userspace threads
>to be woken up less frequently.
>
>Co-developed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
>---
> drivers/gpu/drm/xe/xe_oa.c       | 30 ++++++++++++++++++++++++++----
> drivers/gpu/drm/xe/xe_oa_types.h |  3 +++
> drivers/gpu/drm/xe/xe_query.c    |  2 +-
> include/uapi/drm/xe_drm.h        |  7 +++++++
> 4 files changed, 37 insertions(+), 5 deletions(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
>index ec88b18e9baa2..56bf375a9d4bc 100644
>--- a/drivers/gpu/drm/xe/xe_oa.c
>+++ b/drivers/gpu/drm/xe/xe_oa.c
>@@ -97,6 +97,7 @@ struct xe_oa_open_param {
> 	int num_syncs;
> 	struct xe_sync_entry *syncs;
> 	size_t oa_buffer_size;
>+	int wait_num_reports;
> };
>
> struct xe_oa_config_bo {
>@@ -241,11 +242,10 @@ static void oa_timestamp_clear(struct xe_oa_stream *stream, u32 *report)
> static bool xe_oa_buffer_check_unlocked(struct xe_oa_stream *stream)
> {
> 	u32 gtt_offset = xe_bo_ggtt_addr(stream->oa_buffer.bo);
>+	u32 tail, hw_tail, partial_report_size, available;
> 	int report_size = stream->oa_buffer.format->size;
>-	u32 tail, hw_tail;
> 	unsigned long flags;
> 	bool pollin;
>-	u32 partial_report_size;
>
> 	spin_lock_irqsave(&stream->oa_buffer.ptr_lock, flags);
>
>@@ -289,8 +289,8 @@ static bool xe_oa_buffer_check_unlocked(struct xe_oa_stream *stream)
>
> 	stream->oa_buffer.tail = tail;
>
>-	pollin = xe_oa_circ_diff(stream, stream->oa_buffer.tail,
>-				 stream->oa_buffer.head) >= report_size;
>+	available = xe_oa_circ_diff(stream, stream->oa_buffer.tail, stream->oa_buffer.head);
>+	pollin = available >= stream->wait_num_reports * report_size;
>
> 	spin_unlock_irqrestore(&stream->oa_buffer.ptr_lock, flags);
>
>@@ -1285,6 +1285,17 @@ static int xe_oa_set_prop_oa_buffer_size(struct xe_oa *oa, u64 value,
> 	return 0;
> }
>
>+static int xe_oa_set_prop_wait_num_reports(struct xe_oa *oa, u64 value,
>+					   struct xe_oa_open_param *param)
>+{
>+	if (!value) {
>+		drm_dbg(&oa->xe->drm, "wait_num_reports %llu\n", value);
>+		return -EINVAL;
>+	}
>+	param->wait_num_reports = value;
>+	return 0;
>+}
>+
> static int xe_oa_set_prop_ret_inval(struct xe_oa *oa, u64 value,
> 				    struct xe_oa_open_param *param)
> {
>@@ -1306,6 +1317,7 @@ static const xe_oa_set_property_fn xe_oa_set_property_funcs_open[] = {
> 	[DRM_XE_OA_PROPERTY_NUM_SYNCS] = xe_oa_set_prop_num_syncs,
> 	[DRM_XE_OA_PROPERTY_SYNCS] = xe_oa_set_prop_syncs_user,
> 	[DRM_XE_OA_PROPERTY_OA_BUFFER_SIZE] = xe_oa_set_prop_oa_buffer_size,
>+	[DRM_XE_OA_PROPERTY_WAIT_NUM_REPORTS] = xe_oa_set_prop_wait_num_reports,
> };
>
> static const xe_oa_set_property_fn xe_oa_set_property_funcs_config[] = {
>@@ -1321,6 +1333,7 @@ static const xe_oa_set_property_fn xe_oa_set_property_funcs_config[] = {
> 	[DRM_XE_OA_PROPERTY_NUM_SYNCS] = xe_oa_set_prop_num_syncs,
> 	[DRM_XE_OA_PROPERTY_SYNCS] = xe_oa_set_prop_syncs_user,
> 	[DRM_XE_OA_PROPERTY_OA_BUFFER_SIZE] = xe_oa_set_prop_ret_inval,
>+	[DRM_XE_OA_PROPERTY_WAIT_NUM_REPORTS] = xe_oa_set_prop_ret_inval,
> };
>
> static int xe_oa_user_ext_set_property(struct xe_oa *oa, enum xe_oa_user_extn_from from,
>@@ -1797,6 +1810,7 @@ static int xe_oa_stream_init(struct xe_oa_stream *stream,
> 	stream->periodic = param->period_exponent > 0;
> 	stream->period_exponent = param->period_exponent;
> 	stream->no_preempt = param->no_preempt;
>+	stream->wait_num_reports = param->wait_num_reports;
>
> 	stream->xef = xe_file_get(param->xef);
> 	stream->num_syncs = param->num_syncs;
>@@ -2156,6 +2170,14 @@ int xe_oa_stream_open_ioctl(struct drm_device *dev, u64 data, struct drm_file *f
> 	if (!param.oa_buffer_size)
> 		param.oa_buffer_size = DEFAULT_XE_OA_BUFFER_SIZE;
>
>+	if (!param.wait_num_reports)
>+		param.wait_num_reports = 1;
>+	if (param.wait_num_reports > param.oa_buffer_size / f->size) {
>+		drm_dbg(&oa->xe->drm, "wait_num_reports %d\n", param.wait_num_reports);
>+		ret = -EINVAL;
>+		goto err_exec_q;
>+	}

If possible, I think this check where wait_num_reports has an upper 
limit should be moved to xe_oa_set_prop_wait_num_reports().

With that, 

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

Thanks,
Umesh

>+
> 	ret = xe_oa_parse_syncs(oa, &param);
> 	if (ret)
> 		goto err_exec_q;
>diff --git a/drivers/gpu/drm/xe/xe_oa_types.h b/drivers/gpu/drm/xe/xe_oa_types.h
>index df77939156288..2dcd3b9562e97 100644
>--- a/drivers/gpu/drm/xe/xe_oa_types.h
>+++ b/drivers/gpu/drm/xe/xe_oa_types.h
>@@ -218,6 +218,9 @@ struct xe_oa_stream {
> 	/** @pollin: Whether there is data available to read */
> 	bool pollin;
>
>+	/** @wait_num_reports: Number of reports to wait for before signalling pollin */
>+	int wait_num_reports;
>+
> 	/** @periodic: Whether periodic sampling is currently enabled */
> 	bool periodic;
>
>diff --git a/drivers/gpu/drm/xe/xe_query.c b/drivers/gpu/drm/xe/xe_query.c
>index d2a816f71bf26..226b234d07110 100644
>--- a/drivers/gpu/drm/xe/xe_query.c
>+++ b/drivers/gpu/drm/xe/xe_query.c
>@@ -672,7 +672,7 @@ static int query_oa_units(struct xe_device *xe,
> 			du->oa_unit_type = u->type;
> 			du->oa_timestamp_freq = xe_oa_timestamp_frequency(gt);
> 			du->capabilities = DRM_XE_OA_CAPS_BASE | DRM_XE_OA_CAPS_SYNCS |
>-					   DRM_XE_OA_CAPS_OA_BUFFER_SIZE;
>+				DRM_XE_OA_CAPS_OA_BUFFER_SIZE | DRM_XE_OA_CAPS_WAIT_NUM_REPORTS;
>
> 			j = 0;
> 			for_each_hw_engine(hwe, gt, hwe_id) {
>diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
>index 0383b52cbd869..f62689ca861a4 100644
>--- a/include/uapi/drm/xe_drm.h
>+++ b/include/uapi/drm/xe_drm.h
>@@ -1487,6 +1487,7 @@ struct drm_xe_oa_unit {
> #define DRM_XE_OA_CAPS_BASE		(1 << 0)
> #define DRM_XE_OA_CAPS_SYNCS		(1 << 1)
> #define DRM_XE_OA_CAPS_OA_BUFFER_SIZE	(1 << 2)
>+#define DRM_XE_OA_CAPS_WAIT_NUM_REPORTS	(1 << 3)
>
> 	/** @oa_timestamp_freq: OA timestamp freq */
> 	__u64 oa_timestamp_freq;
>@@ -1660,6 +1661,12 @@ enum drm_xe_oa_property_id {
> 	 * buffer is allocated by default.
> 	 */
> 	DRM_XE_OA_PROPERTY_OA_BUFFER_SIZE,
>+
>+	/**
>+	 * @DRM_XE_OA_PROPERTY_WAIT_NUM_REPORTS: Number of reports to wait
>+	 * for before unblocking poll or read
>+	 */
>+	DRM_XE_OA_PROPERTY_WAIT_NUM_REPORTS,
> };
>
> /**
>-- 
>2.47.1
>