[Intel-gfx] [PATCH 1/3] drm/i915: Keep track of request counts

[Ben Widawsky]

There is already a list of requests outstanding for a given client.
Keeping a count is easy, and will give some information necessary to
enable a more fair throttling scheme.

For now a client is uniquely identified by its file descriptor, however
this may change in the future with new process APIs.

Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
---
 drivers/gpu/drm/i915/i915_drv.h |    1 +
 drivers/gpu/drm/i915/i915_gem.c |    8 ++++++++
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 06a37f4..a251d22 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -919,6 +919,7 @@ struct drm_i915_file_private {
 	struct {
 		struct spinlock lock;
 		struct list_head request_list;
+		atomic_t outstanding_requests;
 	} mm;
 };
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6651c36..20d8a41 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1678,6 +1678,7 @@ i915_add_request(struct intel_ring_buffer *ring,
 		request->file_priv = file_priv;
 		list_add_tail(&request->client_list,
 			      &file_priv->mm.request_list);
+		atomic_inc(&file_priv->mm.outstanding_requests);
 		spin_unlock(&file_priv->mm.lock);
 	}
 
@@ -1706,6 +1707,10 @@ i915_gem_request_remove_from_client(struct drm_i915_gem_request *request)
 
 	spin_lock(&file_priv->mm.lock);
 	if (request->file_priv) {
+		atomic_dec(&file_priv->mm.outstanding_requests);
+		if (WARN_ON(atomic_read(&file_priv->mm.outstanding_requests) < 0)) {
+			atomic_set(&file_priv->mm.outstanding_requests, 0);
+		}
 		list_del(&request->client_list);
 		request->file_priv = NULL;
 	}
@@ -4119,6 +4124,9 @@ void i915_gem_release(struct drm_device *dev, struct drm_file *file)
 					   struct drm_i915_gem_request,
 					   client_list);
 		list_del(&request->client_list);
+		atomic_dec(&file_priv->mm.outstanding_requests);
+		if (WARN_ON(atomic_read(&file_priv->mm.outstanding_requests)))
+			atomic_set(&file_priv->mm.outstanding_requests, 0);
 		request->file_priv = NULL;
 	}
 	spin_unlock(&file_priv->mm.lock);
-- 
1.7.7.1