Re: [PATCH 2/3] drm/xe: Exec queue op's to enable/disable preemption and timeslicing

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

On Tue, Jun 25, 2024 at 02:57:15PM -0700, Umesh Nerlige Ramappa wrote:
> On Tue, Jun 25, 2024 at 01:15:17PM -0700, Ashutosh Dixit wrote:
> > Introduce set_no_preempt and clear_no_preempt exec queue ops.
> > set_no_preempt allows an exec queue to run uninterrupted (without
> > preemption or timeslicing). clear_no_preempt re-enables preemption and
> > timeslicing. The functionality is used in OA in the next patch.
> > 
> > Cc: Matthew Brost <matthew.brost@intel.com>
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> > ---
> > drivers/gpu/drm/xe/xe_exec_queue_types.h |  4 +++
> > drivers/gpu/drm/xe/xe_execlist.c         | 14 ++++++++
> > drivers/gpu/drm/xe/xe_guc_submit.c       | 45 ++++++++++++++++++++++++
> > 3 files changed, 63 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_exec_queue_types.h b/drivers/gpu/drm/xe/xe_exec_queue_types.h
> > index 201588ec33c3..8d64c2277e96 100644
> > --- a/drivers/gpu/drm/xe/xe_exec_queue_types.h
> > +++ b/drivers/gpu/drm/xe/xe_exec_queue_types.h
> > @@ -164,6 +164,10 @@ struct xe_exec_queue_ops {
> > 	int (*set_timeslice)(struct xe_exec_queue *q, u32 timeslice_us);
> > 	/** @set_preempt_timeout: Set preemption timeout for exec queue */
> > 	int (*set_preempt_timeout)(struct xe_exec_queue *q, u32 preempt_timeout_us);
> > +	/** @set_no_preempt: Disable preemption and timeslicing for exec queue */
> > +	int (*set_no_preempt)(struct xe_exec_queue *q);
> > +	/** @clear_no_preempt: Re-enable preemption and timeslicing for exec queue */
> > +	int (*clear_no_preempt)(struct xe_exec_queue *q);
> > 	/**
> > 	 * @suspend: Suspend exec queue from executing, allowed to be called
> > 	 * multiple times in a row before resume with the caveat that
> > diff --git a/drivers/gpu/drm/xe/xe_execlist.c b/drivers/gpu/drm/xe/xe_execlist.c
> > index db906117db6d..04a2c7e86019 100644
> > --- a/drivers/gpu/drm/xe/xe_execlist.c
> > +++ b/drivers/gpu/drm/xe/xe_execlist.c
> > @@ -416,6 +416,18 @@ static int execlist_exec_queue_set_preempt_timeout(struct xe_exec_queue *q,
> > 	return 0;
> > }
> > 
> > +static int execlist_exec_queue_set_no_preempt(struct xe_exec_queue *q)
> > +{
> > +	/* NIY */
> > +	return 0;
> > +}
> > +
> > +static int execlist_exec_queue_clear_no_preempt(struct xe_exec_queue *q)
> > +{
> > +	/* NIY */
> > +	return 0;
> > +}
> > +
> > static int execlist_exec_queue_suspend(struct xe_exec_queue *q)
> > {
> > 	/* NIY */
> > @@ -446,6 +458,8 @@ static const struct xe_exec_queue_ops execlist_exec_queue_ops = {
> > 	.set_priority = execlist_exec_queue_set_priority,
> > 	.set_timeslice = execlist_exec_queue_set_timeslice,
> > 	.set_preempt_timeout = execlist_exec_queue_set_preempt_timeout,
> > +	.set_no_preempt = execlist_exec_queue_set_no_preempt,
> > +	.clear_no_preempt = execlist_exec_queue_clear_no_preempt,
> > 	.suspend = execlist_exec_queue_suspend,
> > 	.suspend_wait = execlist_exec_queue_suspend_wait,
> > 	.resume = execlist_exec_queue_resume,
> > diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
> > index 373447758a60..3fd5523baf0f 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_submit.c
> > +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
> > @@ -1548,6 +1548,49 @@ static int guc_exec_queue_set_preempt_timeout(struct xe_exec_queue *q,
> > 	return 0;
> > }
> > 
> > +static int guc_exec_queue_set_no_preempt(struct xe_exec_queue *q)
> > +{
> > +	struct xe_sched_msg *msg;
> > +
> > +	if ((!q->sched_props.preempt_timeout_us && !q->sched_props.timeslice_us) ||
> > +	    exec_queue_killed_or_banned_or_wedged(q))
> > +		return 0;
> > +
> > +	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
> > +	if (!msg)
> > +		return -ENOMEM;
> > +
> > +	/* Setting values to 0 will disable preemption and timeslicing */
> > +	q->sched_props.preempt_timeout_us = 0;
> > +	q->sched_props.timeslice_us = 0;
> > +
> > +	guc_exec_queue_add_msg(q, msg, SET_SCHED_PROPS);
> > +
> > +	return 0;
> > +}
> > +
> > +static int guc_exec_queue_clear_no_preempt(struct xe_exec_queue *q)
> > +{
> > +	struct xe_sched_msg *msg;
> > +
> > +	if ((q->sched_props.preempt_timeout_us ==
> > +	    q->hwe->eclass->sched_props.preempt_timeout_us &&
> > +	    q->sched_props.timeslice_us == q->hwe->eclass->sched_props.timeslice_us) ||
> > +	    exec_queue_killed_or_banned_or_wedged(q))
> > +		return 0;
> > +
> > +	msg = kmalloc(sizeof(*msg), GFP_KERNEL);
> > +	if (!msg)
> > +		return -ENOMEM;
> > +
> > +	q->sched_props.preempt_timeout_us = q->hwe->eclass->sched_props.preempt_timeout_us;
> > +	q->sched_props.timeslice_us = q->hwe->eclass->sched_props.timeslice_us;
> > +
> > +	guc_exec_queue_add_msg(q, msg, SET_SCHED_PROPS);
> > +
> > +	return 0;
> > +}
> 
> Why not just use the .set_timeslice and .set_preempt_timeout hooks instead
> of defining a new one to do both?
> 
> Also how do you check if this operation succeeeded? Is there a response from
> GuC indicating success?
> 

Umesh's thinking seems correct. 

Just use the existing set_timeslice & set_preempt_timeout hooks with 0
for disable and q->hwe->eclass->sched_props.timeslice_us for enable.

Matt

> Thanks,
> Umesh
> 
> > +
> > static int guc_exec_queue_suspend(struct xe_exec_queue *q)
> > {
> > 	struct xe_sched_msg *msg = q->guc->static_msgs + STATIC_MSG_SUSPEND;
> > @@ -1598,6 +1641,8 @@ static const struct xe_exec_queue_ops guc_exec_queue_ops = {
> > 	.set_priority = guc_exec_queue_set_priority,
> > 	.set_timeslice = guc_exec_queue_set_timeslice,
> > 	.set_preempt_timeout = guc_exec_queue_set_preempt_timeout,
> > +	.set_no_preempt = guc_exec_queue_set_no_preempt,
> > +	.clear_no_preempt = guc_exec_queue_clear_no_preempt,
> > 	.suspend = guc_exec_queue_suspend,
> > 	.suspend_wait = guc_exec_queue_suspend_wait,
> > 	.resume = guc_exec_queue_resume,
> > -- 
> > 2.41.0
> >