Messages in this thread | | | Subject | Re: [PATCH 4/6] drm/i915: Fix lock order reversal in shmem pread path. | From | Keith Packard <> | Date | Wed, 25 Mar 2009 21:03:13 -0700 |
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On Wed, 2009-03-25 at 23:30 +0000, Dave Airlie wrote: > > I've no idea when a fault is likely in the fast case, i.e. will it happen > usually on the first page etc, because if it happens on the last page and > you fallback and restart the whole copy, I would think that would be > sub-optimal, granted it could get ugly quick, but this code has already > hit a few branches on the tree.
The data in question is presumably 'hot', and so unlikely to be swapped out. Testing the slow paths doing a complete copy is fairly easy, while testing partial copies would be considerably more difficult. The combination of these two seems to encourage a careful and simplistic slow path.
We can always make it 'faster' in the future, but having it wrong from the first seems sub-optimal.
-- keith.packard@intel.com [unhandled content-type:application/pgp-signature] | |