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[10/16] drm/i915: Retire requests before disabling pagefaults

Message ID 1305235044-9159-11-git-send-email-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Wilson May 12, 2011, 9:17 p.m. UTC 
As we cannot wait upon an object to be released by the GPU once we have
disabled pagefaults, process any pending retirements first in the hope
that we move any potential relocations off the active list.

References: https://bugs.freedesktop.org/show_bug.cgi?id=35733
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

Comments

Keith Packard May 13, 2011, 1:08 a.m. UTC | #1 
On Thu, 12 May 2011 22:17:18 +0100, Chris Wilson <chris@chris-wilson.co.uk> wrote:

> As we cannot wait upon an object to be released by the GPU once we have
> disabled pagefaults, process any pending retirements first in the hope
> that we move any potential relocations off the active list.

This seems to indicate a problem in user space. In any hot-path code,
user space should already have correctly computed the relocation
values and so the kernel should not have to map and re-write the value.

Kernel relocations are a requirement of the architecture, but not
something we should hit in practice once the application has gotten
itself running in a steady state.
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 20a4cc5..3c639ba 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -446,6 +446,12 @@  i915_gem_execbuffer_relocate(struct drm_device *dev,
 	struct drm_i915_gem_object *obj;
 	int ret = 0;
 
+	/* Try to move as many of the relocation targets off the active list
+	 * to avoid unnecessary fallbacks to the slow path, as we cannot wait
+	 * for the retirement with pagefaults disabled.
+	 */
+	i915_gem_retire_requests(dev);
+
 	/* This is the fast path and we cannot handle a pagefault whilst
 	 * holding the struct mutex lest the user pass in the relocations
 	 * contained within a mmaped bo. For in such a case we, the page