[Intel-gfx] [PATCH 10/28] drm/i915: Show timeline dependencies for debug

[Tvrtko Ursulin]

On 17/11/2020 11:30, Chris Wilson wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> Include the signalers each request in the timeline is waiting on, as a
> means to try and identify the cause of a stall. This can be quite
> verbose, even as for now we only show each request in the timeline and
> its immediate antecedents.
> 
> This generates output like:
> 
> Timeline 886: { count 1, ready: 0, inflight: 0, seqno: { current: 664, last: 666 }, engine: rcs0 }

Applies to earlier patch:

I am still tempted to suggest replacing "current: %d, last: %d" with 
"seqno: %d/%d" for compactness and which is still completely intuitive 
to me.

And maybe instead of "engine: %s" just append the engine name direct as tag.

But up to you.

>    U 886:29a-  prio=0 @ 134ms: gem_exec_parall<4621>
>    - U bc1:27a-  prio=0 @ 134ms: gem_exec_parall[4917]
> Timeline 825: { count 1, ready: 0, inflight: 0, seqno: { current: 802, last: 804 }, engine: vcs0 }
>    U 825:324  prio=0 @ 107ms: gem_exec_parall<4518>
>    - U b75:140-  prio=0 @ 110ms: gem_exec_parall<5486>
> Timeline b46: { count 1, ready: 0, inflight: 0, seqno: { current: 782, last: 784 }, engine: vcs0 }
>    U b46:310-  prio=0 @ 70ms: gem_exec_parall<5428>
>    - U c11:170-  prio=0 @ 70ms: gem_exec_parall[5501]
> Timeline 96b: { count 1, ready: 0, inflight: 0, seqno: { current: 632, last: 634 }, engine: vcs0 }
>    U 96b:27a-  prio=0 @ 67ms: gem_exec_parall<4878>
>    - U b75:19e-  prio=0 @ 67ms: gem_exec_parall<5486>
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_debugfs.c   |  3 ++-
>   drivers/gpu/drm/i915/i915_scheduler.c | 31 +++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/i915_scheduler.h |  6 ++++++
>   3 files changed, 39 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 498c82dcc7e9..f6e71119891f 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -45,6 +45,7 @@
>   #include "i915_debugfs.h"
>   #include "i915_debugfs_params.h"
>   #include "i915_irq.h"
> +#include "i915_scheduler.h"
>   #include "i915_trace.h"
>   #include "intel_pm.h"
>   #include "intel_sideband.h"
> @@ -1325,7 +1326,7 @@ static int i915_engine_info(struct seq_file *m, void *unused)
>   	for_each_uabi_engine(engine, i915)
>   		intel_engine_dump(engine, &p, "%s\n", engine->name);
>   
> -	intel_gt_show_timelines(&i915->gt, &p, NULL);
> +	intel_gt_show_timelines(&i915->gt, &p, i915_request_show_with_schedule);
>   
>   	intel_runtime_pm_put(&i915->runtime_pm, wakeref);
>   
> diff --git a/drivers/gpu/drm/i915/i915_scheduler.c b/drivers/gpu/drm/i915/i915_scheduler.c
> index cbb880b10c65..8837ba672933 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler.c
> +++ b/drivers/gpu/drm/i915/i915_scheduler.c
> @@ -504,6 +504,37 @@ void i915_sched_node_fini(struct i915_sched_node *node)
>   	spin_unlock_irq(&schedule_lock);
>   }
>   
> +void i915_request_show_with_schedule(struct drm_printer *m,
> +				     const struct i915_request *rq,
> +				     const char *prefix)
> +{
> +	struct i915_dependency *dep;
> +
> +	i915_request_show(m, rq, prefix);
> +	if (i915_request_completed(rq))
> +		return;
> +
> +	rcu_read_lock();
> +	for_each_signaler(dep, rq) {
> +		const struct i915_request *signaler =
> +			node_to_request(dep->signaler);
> +
> +		/* Dependencies along the same timeline are expected. */
> +		if (signaler->timeline == rq->timeline)
> +			continue;
> +
> +		if (i915_request_completed(signaler))
> +			continue;
> +
> +		/* XXX ideally build indent into prefix */
> +		i915_request_show(m, signaler,
> +				  i915_request_is_active(signaler) ? "  - E" :
> +				  i915_request_is_ready(signaler) ? "  - Q" :
> +				  "  - U");

This we will see what we agree on in the previous patch.

> +	}
> +	rcu_read_unlock();
> +}
> +
>   static void i915_global_scheduler_shrink(void)
>   {
>   	kmem_cache_shrink(global.slab_dependencies);
> diff --git a/drivers/gpu/drm/i915/i915_scheduler.h b/drivers/gpu/drm/i915/i915_scheduler.h
> index 6f0bf00fc569..34cee9a17801 100644
> --- a/drivers/gpu/drm/i915/i915_scheduler.h
> +++ b/drivers/gpu/drm/i915/i915_scheduler.h
> @@ -13,6 +13,8 @@
>   
>   #include "i915_scheduler_types.h"
>   
> +struct drm_printer;
> +
>   #define priolist_for_each_request(it, plist, idx) \
>   	for (idx = 0; idx < ARRAY_SIZE((plist)->requests); idx++) \
>   		list_for_each_entry(it, &(plist)->requests[idx], sched.link)
> @@ -54,4 +56,8 @@ static inline void i915_priolist_free(struct i915_priolist *p)
>   		__i915_priolist_free(p);
>   }
>   
> +void i915_request_show_with_schedule(struct drm_printer *m,
> +				     const struct i915_request *rq,
> +				     const char *prefix);
> +
>   #endif /* _I915_SCHEDULER_H_ */
> 

Overall looks good to me.

Regards,

Tvrtko