[Intel-gfx] [PATCH v3 4/7] drm/i915: Cache LRC state page in the context

Chris Wilson chris at chris-wilson.co.uk
Tue Jan 12 04:12:23 PST 2016

On Tue, Jan 12, 2016 at 11:56:11AM +0000, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> LRC lifetime is well defined so we can cache the page pointing
> to the object backing store in the context in order to avoid
> walking over the object SG page list from the interrupt context
> without the big lock held.
> v2: Also cache the mapping. (Chris Wilson)
> v3: Unmap on the error path.

Then we only use the lrc_state_page in the unmapping, hardly worth the
cost of saving it.

The reg_state is better associated with the ring (since it basically
contains the analog of the RING_HEAD and friends).

Chris Wilson, Intel Open Source Technology Centre

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