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drm/i915: Convert non-blocking waits for requests over to using RCU

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We can completely avoid taking the struct_mutex around the non-blocking
waits by switching over to the RCU request management (trading the mutex
for a RCU read lock and some complex atomic operations). The improvement
is that we gain further contention reduction, and overall the code
become simpler due to the reduced mutex dancing.

v2: Move i915_gem_fault tracepoint back to the start of the function,
before the unlocked wait.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1470388464-28458-2-git-send-email-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2016-08-05 10:14:07 +01:00
parent 2467658e2d
commit b8f9096d6a
1 changed files with 48 additions and 66 deletions
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114
drivers/gpu/drm/i915/i915_gem.c
View File

@ -349,24 +349,20 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
return 0;
}
/* A nonblocking variant of the above wait. This is a highly dangerous routine
* as the object state may change during this call.
/* A nonblocking variant of the above wait. Must be called prior to
* acquiring the mutex for the object, as the object state may change
* during this call. A reference must be held by the caller for the object.
*/
static __must_check int
i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
struct intel_rps_client *rps,
bool readonly)
__unsafe_wait_rendering(struct drm_i915_gem_object *obj,
struct intel_rps_client *rps,
bool readonly)
{
struct drm_device *dev = obj->base.dev;
struct drm_i915_gem_request *requests[I915_NUM_ENGINES];
struct i915_gem_active *active;
unsigned long active_mask;
int ret, i, n = 0;
int idx;
lockdep_assert_held(&dev->struct_mutex);
GEM_BUG_ON(!to_i915(dev)->mm.interruptible);
active_mask = i915_gem_object_get_active(obj);
active_mask = __I915_BO_ACTIVE(obj);
if (!active_mask)
return 0;
@ -377,25 +373,16 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
active = &obj->last_write;
}
for_each_active(active_mask, i) {
struct drm_i915_gem_request *req;
for_each_active(active_mask, idx) {
int ret;
req = i915_gem_active_get(&active[i],
&obj->base.dev->struct_mutex);
if (req)
requests[n++] = req;
ret = i915_gem_active_wait_unlocked(&active[idx],
true, NULL, rps);
if (ret)
return ret;
}
mutex_unlock(&dev->struct_mutex);
ret = 0;
for (i = 0; ret == 0 && i < n; i++)
ret = i915_wait_request(requests[i], true, NULL, rps);
mutex_lock(&dev->struct_mutex);
for (i = 0; i < n; i++)
i915_gem_request_put(requests[i]);
return ret;
return 0;
}
static struct intel_rps_client *to_rps_client(struct drm_file *file)
@ -1467,10 +1454,7 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
int ret;
/* Only handle setting domains to types used by the CPU. */
if (write_domain & I915_GEM_GPU_DOMAINS)
return -EINVAL;
if (read_domains & I915_GEM_GPU_DOMAINS)
if ((write_domain | read_domains) & I915_GEM_GPU_DOMAINS)
return -EINVAL;
/* Having something in the write domain implies it's in the read
@ -1479,25 +1463,21 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
if (write_domain != 0 && read_domains != write_domain)
return -EINVAL;
ret = i915_mutex_lock_interruptible(dev);
if (ret)
return ret;
obj = i915_gem_object_lookup(file, args->handle);
if (!obj) {
ret = -ENOENT;
goto unlock;
}
if (!obj)
return -ENOENT;
/* Try to flush the object off the GPU without holding the lock.
* We will repeat the flush holding the lock in the normal manner
* to catch cases where we are gazumped.
*/
ret = i915_gem_object_wait_rendering__nonblocking(obj,
to_rps_client(file),
!write_domain);
ret = __unsafe_wait_rendering(obj, to_rps_client(file), !write_domain);
if (ret)
goto unref;
goto err;
ret = i915_mutex_lock_interruptible(dev);
if (ret)
goto err;
if (read_domains & I915_GEM_DOMAIN_GTT)
ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);
@ -1507,11 +1487,13 @@ i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
if (write_domain != 0)
intel_fb_obj_invalidate(obj, write_origin(obj, write_domain));
unref:
i915_gem_object_put(obj);
unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
err:
i915_gem_object_put_unlocked(obj);
return ret;
}
/**
@ -1648,36 +1630,36 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
struct drm_i915_private *dev_priv = to_i915(dev);
struct i915_ggtt *ggtt = &dev_priv->ggtt;
struct i915_ggtt_view view = i915_ggtt_view_normal;
bool write = !!(vmf->flags & FAULT_FLAG_WRITE);
pgoff_t page_offset;
unsigned long pfn;
int ret = 0;
bool write = !!(vmf->flags & FAULT_FLAG_WRITE);
intel_runtime_pm_get(dev_priv);
int ret;
/* We don't use vmf->pgoff since that has the fake offset */
page_offset = ((unsigned long)vmf->virtual_address - vma->vm_start) >>
PAGE_SHIFT;
ret = i915_mutex_lock_interruptible(dev);
if (ret)
goto out;
trace_i915_gem_object_fault(obj, page_offset, true, write);
/* Try to flush the object off the GPU first without holding the lock.
* Upon reacquiring the lock, we will perform our sanity checks and then
* Upon acquiring the lock, we will perform our sanity checks and then
* repeat the flush holding the lock in the normal manner to catch cases
* where we are gazumped.
*/
ret = i915_gem_object_wait_rendering__nonblocking(obj, NULL, !write);
ret = __unsafe_wait_rendering(obj, NULL, !write);
if (ret)
goto unlock;
goto err;
intel_runtime_pm_get(dev_priv);
ret = i915_mutex_lock_interruptible(dev);
if (ret)
goto err_rpm;
/* Access to snoopable pages through the GTT is incoherent. */
if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev)) {
ret = -EFAULT;
goto unlock;
goto err_unlock;
}
/* Use a partial view if the object is bigger than the aperture. */
@ -1698,15 +1680,15 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
/* Now pin it into the GTT if needed */
ret = i915_gem_object_ggtt_pin(obj, &view, 0, 0, PIN_MAPPABLE);
if (ret)
goto unlock;
goto err_unlock;
ret = i915_gem_object_set_to_gtt_domain(obj, write);
if (ret)
goto unpin;
goto err_unpin;
ret = i915_gem_object_get_fence(obj);
if (ret)
goto unpin;
goto err_unpin;
/* Finally, remap it using the new GTT offset */
pfn = ggtt->mappable_base +
@ -1751,11 +1733,13 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
(unsigned long)vmf->virtual_address,
pfn + page_offset);
}
unpin:
err_unpin:
i915_gem_object_ggtt_unpin_view(obj, &view);
unlock:
err_unlock:
mutex_unlock(&dev->struct_mutex);
out:
err_rpm:
intel_runtime_pm_put(dev_priv);
err:
switch (ret) {
case -EIO:
/*
@ -1796,8 +1780,6 @@ out:
ret = VM_FAULT_SIGBUS;
break;
}
intel_runtime_pm_put(dev_priv);
return ret;
}