drm/i915: Store the reset counter when constructing a request
As the request is only valid during the same global reset epoch, we can
record the current reset_counter when constructing the request and reuse
it when waiting upon that request in future. This removes a very hairy
atomic check serialised by the struct_mutex at the time of waiting and
allows us to transfer those waits to a central dispatcher for all
waiters and all requests.
PS: With per-engine resets, we obviously cannot assume a global reset
epoch for the requests - a per-engine epoch makes the most sense. The
challenge then is how to handle checking in the waiter for when to break
the wait, as the fine-grained reset may also want to requeue the
request (i.e. the assumption that just because the epoch changes the
request is completed may be broken - or we just avoid breaking that
assumption with the fine-grained resets).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1460565315-7748-7-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index defb445..a62a5ec 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1213,7 +1213,6 @@
/**
* __i915_wait_request - wait until execution of request has finished
* @req: duh!
- * @reset_counter: reset sequence associated with the given request
* @interruptible: do an interruptible wait (normally yes)
* @timeout: in - how long to wait (NULL forever); out - how much time remaining
*
@@ -1228,7 +1227,6 @@
* errno with remaining time filled in timeout argument.
*/
int __i915_wait_request(struct drm_i915_gem_request *req,
- unsigned reset_counter,
bool interruptible,
s64 *timeout,
struct intel_rps_client *rps)
@@ -1290,7 +1288,7 @@
/* We need to check whether any gpu reset happened in between
* the caller grabbing the seqno and now ... */
- if (reset_counter != i915_reset_counter(&dev_priv->gpu_error)) {
+ if (req->reset_counter != i915_reset_counter(&dev_priv->gpu_error)) {
/* ... but upgrade the -EAGAIN to an -EIO if the gpu
* is truely gone. */
ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
@@ -1460,13 +1458,7 @@
BUG_ON(!mutex_is_locked(&dev->struct_mutex));
- ret = i915_gem_check_wedge(&dev_priv->gpu_error, interruptible);
- if (ret)
- return ret;
-
- ret = __i915_wait_request(req,
- i915_reset_counter(&dev_priv->gpu_error),
- interruptible, NULL, NULL);
+ ret = __i915_wait_request(req, interruptible, NULL, NULL);
if (ret)
return ret;
@@ -1541,7 +1533,6 @@
struct drm_device *dev = obj->base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_i915_gem_request *requests[I915_NUM_ENGINES];
- unsigned reset_counter;
int ret, i, n = 0;
BUG_ON(!mutex_is_locked(&dev->struct_mutex));
@@ -1550,12 +1541,6 @@
if (!obj->active)
return 0;
- ret = i915_gem_check_wedge(&dev_priv->gpu_error, true);
- if (ret)
- return ret;
-
- reset_counter = i915_reset_counter(&dev_priv->gpu_error);
-
if (readonly) {
struct drm_i915_gem_request *req;
@@ -1577,9 +1562,9 @@
}
mutex_unlock(&dev->struct_mutex);
+ ret = 0;
for (i = 0; ret == 0 && i < n; i++)
- ret = __i915_wait_request(requests[i], reset_counter, true,
- NULL, rps);
+ ret = __i915_wait_request(requests[i], true, NULL, rps);
mutex_lock(&dev->struct_mutex);
for (i = 0; i < n; i++) {
@@ -2735,6 +2720,7 @@
struct drm_i915_gem_request **req_out)
{
struct drm_i915_private *dev_priv = to_i915(engine->dev);
+ unsigned reset_counter = i915_reset_counter(&dev_priv->gpu_error);
struct drm_i915_gem_request *req;
int ret;
@@ -2743,6 +2729,11 @@
*req_out = NULL;
+ ret = i915_gem_check_wedge(&dev_priv->gpu_error,
+ dev_priv->mm.interruptible);
+ if (ret)
+ return ret;
+
req = kmem_cache_zalloc(dev_priv->requests, GFP_KERNEL);
if (req == NULL)
return -ENOMEM;
@@ -2754,6 +2745,7 @@
kref_init(&req->ref);
req->i915 = dev_priv;
req->engine = engine;
+ req->reset_counter = reset_counter;
req->ctx = ctx;
i915_gem_context_reference(req->ctx);
@@ -3132,11 +3124,9 @@
int
i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
{
- struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_i915_gem_wait *args = data;
struct drm_i915_gem_object *obj;
struct drm_i915_gem_request *req[I915_NUM_ENGINES];
- unsigned reset_counter;
int i, n = 0;
int ret;
@@ -3170,7 +3160,6 @@
}
drm_gem_object_unreference(&obj->base);
- reset_counter = i915_reset_counter(&dev_priv->gpu_error);
for (i = 0; i < I915_NUM_ENGINES; i++) {
if (obj->last_read_req[i] == NULL)
@@ -3183,7 +3172,7 @@
for (i = 0; i < n; i++) {
if (ret == 0)
- ret = __i915_wait_request(req[i], reset_counter, true,
+ ret = __i915_wait_request(req[i], true,
args->timeout_ns > 0 ? &args->timeout_ns : NULL,
to_rps_client(file));
i915_gem_request_unreference__unlocked(req[i]);
@@ -3215,7 +3204,6 @@
if (!i915_semaphore_is_enabled(obj->base.dev)) {
struct drm_i915_private *i915 = to_i915(obj->base.dev);
ret = __i915_wait_request(from_req,
- i915_reset_counter(&i915->gpu_error),
i915->mm.interruptible,
NULL,
&i915->rps.semaphores);
@@ -4171,7 +4159,6 @@
struct drm_i915_file_private *file_priv = file->driver_priv;
unsigned long recent_enough = jiffies - DRM_I915_THROTTLE_JIFFIES;
struct drm_i915_gem_request *request, *target = NULL;
- unsigned reset_counter;
int ret;
ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
@@ -4196,7 +4183,6 @@
target = request;
}
- reset_counter = i915_reset_counter(&dev_priv->gpu_error);
if (target)
i915_gem_request_reference(target);
spin_unlock(&file_priv->mm.lock);
@@ -4204,7 +4190,7 @@
if (target == NULL)
return 0;
- ret = __i915_wait_request(target, reset_counter, true, NULL, NULL);
+ ret = __i915_wait_request(target, true, NULL, NULL);
if (ret == 0)
queue_delayed_work(dev_priv->wq, &dev_priv->mm.retire_work, 0);