Re: [PATCH 3/3] drm/xe/oa: Allow preemption to be disabled on the stream exec queue

[Matthew Brost <matthew.brost@intel.com>]

On Tue, Jun 25, 2024 at 02:55:20PM -0700, Umesh Nerlige Ramappa wrote:
> On Tue, Jun 25, 2024 at 01:15:18PM -0700, Ashutosh Dixit wrote:
> > Mesa VK_KHR_performance_query use case requires preemption to be disabled
> > for the stream exec queue. Implement this functionality here based on the
> > new set_no_preempt and clear_no_preempt exec queue ops.
> > 
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> 
> lgtm
> 
> Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> 

This patch should be adjusted based Umesh's and my feedback in patch #2.

Matt

> > ---
> > drivers/gpu/drm/xe/xe_oa.c       | 33 +++++++++++++++++++++++++++++++-
> > drivers/gpu/drm/xe/xe_oa_types.h |  3 +++
> > include/uapi/drm/xe_drm.h        |  6 ++++++
> > 3 files changed, 41 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
> > index a68659fd5386..6453c36c4539 100644
> > --- a/drivers/gpu/drm/xe/xe_oa.c
> > +++ b/drivers/gpu/drm/xe/xe_oa.c
> > @@ -80,6 +80,7 @@ struct xe_oa_open_param {
> > 	int engine_instance;
> > 	struct xe_exec_queue *exec_q;
> > 	struct xe_hw_engine *hwe;
> > +	bool no_preempt;
> > };
> > 
> > struct xe_oa_config_bo {
> > @@ -1018,6 +1019,13 @@ static int xe_oa_enable_locked(struct xe_oa_stream *stream)
> > 	if (stream->enabled)
> > 		return 0;
> > 
> > +	if (stream->no_preempt) {
> > +		int ret = stream->exec_q->ops->set_no_preempt(stream->exec_q);
> > +
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > 	xe_oa_stream_enable(stream);
> > 
> > 	stream->enabled = true;
> > @@ -1026,13 +1034,18 @@ static int xe_oa_enable_locked(struct xe_oa_stream *stream)
> > 
> > static int xe_oa_disable_locked(struct xe_oa_stream *stream)
> > {
> > +	int ret = 0;
> > +
> > 	if (!stream->enabled)
> > 		return 0;
> > 
> > 	xe_oa_stream_disable(stream);
> > 
> > +	if (stream->no_preempt)
> > +		ret = stream->exec_q->ops->clear_no_preempt(stream->exec_q);
> > +
> > 	stream->enabled = false;
> > -	return 0;
> > +	return ret;
> > }
> > 
> > static long xe_oa_config_locked(struct xe_oa_stream *stream, u64 arg)
> > @@ -1307,6 +1320,7 @@ static int xe_oa_stream_init(struct xe_oa_stream *stream,
> > 	stream->sample = param->sample;
> > 	stream->periodic = param->period_exponent > 0;
> > 	stream->period_exponent = param->period_exponent;
> > +	stream->no_preempt = param->no_preempt;
> > 
> > 	/*
> > 	 * For Xe2+, when overrun mode is enabled, there are no partial reports at the end
> > @@ -1651,6 +1665,13 @@ static int xe_oa_set_prop_engine_instance(struct xe_oa *oa, u64 value,
> > 	return 0;
> > }
> > 
> > +static int xe_oa_set_no_preempt(struct xe_oa *oa, u64 value,
> > +				struct xe_oa_open_param *param)
> > +{
> > +	param->no_preempt = value;
> > +	return 0;
> > +}
> > +
> > typedef int (*xe_oa_set_property_fn)(struct xe_oa *oa, u64 value,
> > 				     struct xe_oa_open_param *param);
> > static const xe_oa_set_property_fn xe_oa_set_property_funcs[] = {
> > @@ -1662,6 +1683,7 @@ static const xe_oa_set_property_fn xe_oa_set_property_funcs[] = {
> > 	[DRM_XE_OA_PROPERTY_OA_DISABLED] = xe_oa_set_prop_disabled,
> > 	[DRM_XE_OA_PROPERTY_EXEC_QUEUE_ID] = xe_oa_set_prop_exec_queue_id,
> > 	[DRM_XE_OA_PROPERTY_OA_ENGINE_INSTANCE] = xe_oa_set_prop_engine_instance,
> > +	[DRM_XE_OA_PROPERTY_NO_PREEMPT] = xe_oa_set_no_preempt,
> > };
> > 
> > static int xe_oa_user_ext_set_property(struct xe_oa *oa, u64 extension,
> > @@ -1766,6 +1788,15 @@ int xe_oa_stream_open_ioctl(struct drm_device *dev, u64 data, struct drm_file *f
> > 	if (param.exec_q && !param.sample)
> > 		privileged_op = false;
> > 
> > +	if (param.no_preempt) {
> > +		if (!param.exec_q) {
> > +			drm_dbg(&oa->xe->drm, "Preemption disable without exec_q!\n");
> > +			ret = -EINVAL;
> > +			goto err_exec_q;
> > +		}
> > +		privileged_op = true;
> > +	}
> > +
> > 	if (privileged_op && xe_perf_stream_paranoid && !perfmon_capable()) {
> > 		drm_dbg(&oa->xe->drm, "Insufficient privileges to open xe perf stream\n");
> > 		ret = -EACCES;
> > diff --git a/drivers/gpu/drm/xe/xe_oa_types.h b/drivers/gpu/drm/xe/xe_oa_types.h
> > index 706d45577dae..540c3ec53a6d 100644
> > --- a/drivers/gpu/drm/xe/xe_oa_types.h
> > +++ b/drivers/gpu/drm/xe/xe_oa_types.h
> > @@ -235,5 +235,8 @@ struct xe_oa_stream {
> > 
> > 	/** @oa_status: temporary storage for oa_status register value */
> > 	u32 oa_status;
> > +
> > +	/** @no_preempt: Whether preemption and timeslicing is disabled for stream exec_q */
> > +	u32 no_preempt;
> > };
> > #endif
> > diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
> > index b410553faa9b..12eaa8532b5c 100644
> > --- a/include/uapi/drm/xe_drm.h
> > +++ b/include/uapi/drm/xe_drm.h
> > @@ -1611,6 +1611,12 @@ enum drm_xe_oa_property_id {
> > 	 * pass along with @DRM_XE_OA_PROPERTY_EXEC_QUEUE_ID or will default to 0.
> > 	 */
> > 	DRM_XE_OA_PROPERTY_OA_ENGINE_INSTANCE,
> > +
> > +	/**
> > +	 * @DRM_XE_OA_PROPERTY_NO_PREEMPT: Allow preemption and timeslicing
> > +	 * to be disabled for the stream exec queue.
> > +	 */
> > +	DRM_XE_OA_PROPERTY_NO_PREEMPT,
> > };
> > 
> > /**
> > -- 
> > 2.41.0
> >