On Thu, Sep 05, 2013 at 04:48:54PM +0200, Daniel Vetter wrote: > On Thu, Sep 05, 2013 at 03:29:01PM +0100, Chris Wilson wrote: > > The busy-ioctl is frequently called as it is used by clients treating > > buffer objects like fences and polling for completion. These frequent > > calls are especially subject to contention with multiple clients leading > > to a lot of busy-waiting due to mutex_spin_on_owner()). We can, in most > > cases, report whether the bo is idle without touching struct_mutex, and > > only resort to hitting the lock if we need to queue flushes for the bo. > > > > Signed-off-by: Chris Wilson <[email protected]> > > --- > > drivers/gpu/drm/i915/i915_gem.c | 27 +++++++++++++++++++++------ > > 1 file changed, 21 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/i915_gem.c > > b/drivers/gpu/drm/i915/i915_gem.c > > index 3b942ce..fed0b39 100644 > > --- a/drivers/gpu/drm/i915/i915_gem.c > > +++ b/drivers/gpu/drm/i915/i915_gem.c > > @@ -4068,18 +4068,34 @@ i915_gem_busy_ioctl(struct drm_device *dev, void > > *data, > > { > > struct drm_i915_gem_busy *args = data; > > struct drm_i915_gem_object *obj; > > + struct intel_ring_buffer *ring; > > int ret; > > > > - ret = i915_mutex_lock_interruptible(dev); > > - if (ret) > > - return ret; > > - > > obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle)); > > if (&obj->base == NULL) { > > ret = -ENOENT; > > - goto unlock; > > + goto out_unlocked; > > } > > > > + /* Do an optimistic check for activity - we don't care about userspace > > + * racing with itself, that is always problematic. > > + */ > > + ring = obj->ring; > > + if (ring && obj->last_read_seqno == ring->outstanding_lazy_seqno) > > + goto lock_and_flush; > > Feels a bit too tricky ... How useful is just an > > if (ACCESS_ONCE(obj->active)) > goto lock_and_flush;
Not good enough, still ends up fighting for the lock. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
