Re: [PATCH 18/40] drm/i915: Report the number of closed vma held by each context in debugfs

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 19/09/2018 20:55, Chris Wilson wrote:
> Include the total size of closed vma when reporting the per_ctx_stats of
> debugfs/i915_gem_objects.

Why do we need/want this?

> Whilst adjusting the context tracking, note that we can simply use our
> list of contexts in i915->contexts rather than circumlocute via
> dev->filelist and the per-file context idr.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_debugfs.c | 113 +++++++++++-----------------
>   1 file changed, 42 insertions(+), 71 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 2ac75bc10afa..6b5cc30f3e09 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -302,6 +302,7 @@ struct file_stats {
>   	u64 total, unbound;
>   	u64 global, shared;
>   	u64 active, inactive;
> +	u64 closed;
>   };
>   
>   static int per_file_stats(int id, void *ptr, void *data)
> @@ -336,6 +337,9 @@ static int per_file_stats(int id, void *ptr, void *data)
>   			stats->active += vma->node.size;
>   		else
>   			stats->inactive += vma->node.size;
> +
> +		if (i915_vma_is_closed(vma))
> +			stats->closed += vma->node.size;

We can have closed and active?

>   	}
>   
>   	return 0;
> @@ -343,7 +347,7 @@ static int per_file_stats(int id, void *ptr, void *data)
>   
>   #define print_file_stats(m, name, stats) do { \
>   	if (stats.count) \
> -		seq_printf(m, "%s: %lu objects, %llu bytes (%llu active, %llu inactive, %llu global, %llu shared, %llu unbound)\n", \
> +		seq_printf(m, "%s: %lu objects, %llu bytes (%llu active, %llu inactive, %llu global, %llu shared, %llu unbound, %llu closed)\n", \
>   			   name, \
>   			   stats.count, \
>   			   stats.total, \
> @@ -351,7 +355,8 @@ static int per_file_stats(int id, void *ptr, void *data)
>   			   stats.inactive, \
>   			   stats.global, \
>   			   stats.shared, \
> -			   stats.unbound); \
> +			   stats.unbound, \
> +			   stats.closed); \
>   } while (0)
>   
>   static void print_batch_pool_stats(struct seq_file *m,
> @@ -377,44 +382,44 @@ static void print_batch_pool_stats(struct seq_file *m,
>   	print_file_stats(m, "[k]batch pool", stats);
>   }
>   
> -static int per_file_ctx_stats(int idx, void *ptr, void *data)
> +static void print_context_stats(struct seq_file *m,
> +				struct drm_i915_private *i915)
>   {
> -	struct i915_gem_context *ctx = ptr;
> -	struct intel_engine_cs *engine;
> -	enum intel_engine_id id;
> -
> -	for_each_engine(engine, ctx->i915, id) {
> -		struct intel_context *ce = to_intel_context(ctx, engine);
> +	struct file_stats kstats = {};
> +	struct i915_gem_context *ctx;
>   
> -		if (ce->state)
> -			per_file_stats(0, ce->state->obj, data);
> -		if (ce->ring)
> -			per_file_stats(0, ce->ring->vma->obj, data);
> -	}
> +	list_for_each_entry(ctx, &i915->contexts.list, link) {
> +		struct file_stats stats = { .file_priv = ctx->file_priv };
> +		struct intel_engine_cs *engine;
> +		enum intel_engine_id id;
>   
> -	return 0;
> -}
> +		for_each_engine(engine, i915, id) {
> +			struct intel_context *ce = to_intel_context(ctx, engine);
>   
> -static void print_context_stats(struct seq_file *m,
> -				struct drm_i915_private *dev_priv)
> -{
> -	struct drm_device *dev = &dev_priv->drm;
> -	struct file_stats stats;
> -	struct drm_file *file;
> +			if (ce->state)
> +				per_file_stats(0, ce->state->obj, &kstats);
> +			if (ce->ring)
> +				per_file_stats(0, ce->ring->vma->obj, &kstats);
> +		}
>   
> -	memset(&stats, 0, sizeof(stats));
> +		if (!IS_ERR_OR_NULL(stats.file_priv)) {
> +			struct drm_file *file = stats.file_priv->file;
> +			struct task_struct *task;
>   
> -	mutex_lock(&dev->struct_mutex);
> -	if (dev_priv->kernel_context)
> -		per_file_ctx_stats(0, dev_priv->kernel_context, &stats);
> +			spin_lock(&file->table_lock);
> +			idr_for_each(&file->object_idr, per_file_stats, &stats);

Headache inducing diff.. however, doesn't this over-account objects on 
the account of walking the same file from multiple-contexts?

> +			spin_unlock(&file->table_lock);
>   
> -	list_for_each_entry(file, &dev->filelist, lhead) {
> -		struct drm_i915_file_private *fpriv = file->driver_priv;
> -		idr_for_each(&fpriv->context_idr, per_file_ctx_stats, &stats);
> +			rcu_read_lock();
> +			task = pid_task(ctx->pid ?: file->pid, PIDTYPE_PID);
> +			print_file_stats(m,
> +					 task ? task->comm : "<unknown>",
> +					 stats);

And this as well looks like it'll end up duplicated.

> +			rcu_read_unlock();
> +		}
>   	}
> -	mutex_unlock(&dev->struct_mutex);
>   
> -	print_file_stats(m, "[k]contexts", stats);
> +	print_file_stats(m, "[k]contexts", kstats);
>   }
>   
>   static int i915_gem_object_info(struct seq_file *m, void *data)
> @@ -426,14 +431,9 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>   	u64 size, mapped_size, purgeable_size, dpy_size, huge_size;
>   	struct drm_i915_gem_object *obj;
>   	unsigned int page_sizes = 0;
> -	struct drm_file *file;
>   	char buf[80];
>   	int ret;
>   
> -	ret = mutex_lock_interruptible(&dev->struct_mutex);
> -	if (ret)
> -		return ret;
> -
>   	seq_printf(m, "%u objects, %llu bytes\n",
>   		   dev_priv->mm.object_count,
>   		   dev_priv->mm.object_memory);

Noticed we technically need mm.object_stat_lock here for atomic readout, 
but I guess we don't care much.

> @@ -514,43 +514,14 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
>   					buf, sizeof(buf)));
>   
>   	seq_putc(m, '\n');
> -	print_batch_pool_stats(m, dev_priv);
> -	mutex_unlock(&dev->struct_mutex);
> -
> -	mutex_lock(&dev->filelist_mutex);
> -	print_context_stats(m, dev_priv);
> -	list_for_each_entry_reverse(file, &dev->filelist, lhead) {
> -		struct file_stats stats;
> -		struct drm_i915_file_private *file_priv = file->driver_priv;
> -		struct i915_request *request;
> -		struct task_struct *task;
> -
> -		mutex_lock(&dev->struct_mutex);
>   
> -		memset(&stats, 0, sizeof(stats));
> -		stats.file_priv = file->driver_priv;
> -		spin_lock(&file->table_lock);
> -		idr_for_each(&file->object_idr, per_file_stats, &stats);
> -		spin_unlock(&file->table_lock);
> -		/*
> -		 * Although we have a valid reference on file->pid, that does
> -		 * not guarantee that the task_struct who called get_pid() is
> -		 * still alive (e.g. get_pid(current) => fork() => exit()).
> -		 * Therefore, we need to protect this ->comm access using RCU.
> -		 */
> -		request = list_first_entry_or_null(&file_priv->mm.request_list,
> -						   struct i915_request,
> -						   client_link);
> -		rcu_read_lock();
> -		task = pid_task(request && request->gem_context->pid ?
> -				request->gem_context->pid : file->pid,
> -				PIDTYPE_PID);
> -		print_file_stats(m, task ? task->comm : "<unknown>", stats);
> -		rcu_read_unlock();
> +	ret = mutex_lock_interruptible(&dev->struct_mutex);
> +	if (ret)
> +		return ret;
>   
> -		mutex_unlock(&dev->struct_mutex);
> -	}
> -	mutex_unlock(&dev->filelist_mutex);
> +	print_batch_pool_stats(m, dev_priv);
> +	print_context_stats(m, dev_priv);
> +	mutex_unlock(&dev->struct_mutex);
>   
>   	return 0;
>   }
> 

Regards,

Tvrtko
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