| Message ID | 1344417802-5822-1-git-send-email-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Aug 08, 2012 at 10:23:22AM +0100, Chris Wilson wrote: > Userspace tries to estimate the cost of ring switching based on whether > the GPU and GEM supports semaphores. (If we have multiple rings and no > semaphores, userspace assumes that the cost of switching rings between > batches is exorbitant and will endeavour to keep the next batch on the > active ring - as a coarse approximation to tracking both destination and > source surfaces.) Currently userspace has to guess whether semaphores > exist based on the chipset generation and the module parameter, > i915.semaphores. This is a crude and inaccurate guess as the defaults > internally depend upon other chipset features being enabled or disabled, > nor does it extend well into the future. By exporting a HAS_SEMAPHORES > parameter, we can easily query the driver and obtain an accurate answer. > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Sounds like something useful, applied for -next, thanks for the patch. -Daniel
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c index 9cf7dfe..64fd7be 100644 --- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -1009,6 +1009,9 @@ static int i915_getparam(struct drm_device *dev, void *data, case I915_PARAM_HAS_WAIT_TIMEOUT: value = 1; break; + case I915_PARAM_HAS_SEMAPHORES: + value = i915_semaphore_is_enabled(dev); + break; default: DRM_DEBUG_DRIVER("Unknown parameter %d\n", param->param); diff --git a/include/drm/i915_drm.h b/include/drm/i915_drm.h index 8cc7083..2f0d472 100644 --- a/include/drm/i915_drm.h +++ b/include/drm/i915_drm.h @@ -305,6 +305,7 @@ typedef struct drm_i915_irq_wait { #define I915_PARAM_HAS_LLC 17 #define I915_PARAM_HAS_ALIASING_PPGTT 18 #define I915_PARAM_HAS_WAIT_TIMEOUT 19 +#define I915_PARAM_HAS_SEMAPHORES 20 typedef struct drm_i915_getparam { int param;
Userspace tries to estimate the cost of ring switching based on whether the GPU and GEM supports semaphores. (If we have multiple rings and no semaphores, userspace assumes that the cost of switching rings between batches is exorbitant and will endeavour to keep the next batch on the active ring - as a coarse approximation to tracking both destination and source surfaces.) Currently userspace has to guess whether semaphores exist based on the chipset generation and the module parameter, i915.semaphores. This is a crude and inaccurate guess as the defaults internally depend upon other chipset features being enabled or disabled, nor does it extend well into the future. By exporting a HAS_SEMAPHORES parameter, we can easily query the driver and obtain an accurate answer. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> --- drivers/gpu/drm/i915/i915_dma.c | 3 +++ include/drm/i915_drm.h | 1 + 2 files changed, 4 insertions(+)