[Mesa-dev] [PATCH 2/7] vbo: Add a predraw resolve callback

[Ian Romanick]

On 09/09/2015 10:10 AM, Kenneth Graunke wrote:
> On Wednesday, September 09, 2015 02:38:56 PM Chris Wilson wrote:
>> A common problem with using HiZ and multisampling is that surfaces need
>> to resolved prior to use. Currently i965 does this inside its state
>> update hook, but that is a comparatively heavyweight operation that need
>> not be performed so frequently. The obvious solution (and therefore
>> fraught with dragons) is to move the HiZ/color resolves into the
>> brw_draw_prims() - however, the resolves are performed using meta and
>> end up re-entering brw_draw_prims() corrupting the context state of the
>> original call. To avoid the meta recursion, we can add a new callback
>> (vbo->resolve()) into the vbo pipeline that is called just before
>> vbo->draw().
>>
>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>> Cc: Brian Paul <brianp at vmware.com>
>> Cc: Jordan Justen <jordan.l.justen at intel.com>
>> Cc: Jason Ekstrand <jason.ekstrand at intel.com>
>> Cc: Kenneth Graunke <kenneth at whitecape.org>
>> Cc: Francisco Jerez <currojerez at riseup.net>
>> ---
>>  src/mesa/vbo/vbo.h            |  1 +
>>  src/mesa/vbo/vbo_context.c    | 19 +++++++++++++++++++
>>  src/mesa/vbo/vbo_context.h    |  1 +
>>  src/mesa/vbo/vbo_exec_array.c |  1 +
>>  src/mesa/vbo/vbo_exec_draw.c  |  5 ++++-
>>  src/mesa/vbo/vbo_save_draw.c  |  2 ++
>>  6 files changed, 28 insertions(+), 1 deletion(-)
> 
> What problem are you trying to solve with this patch series?
> Are you trying to fix bugs?  If so, what triggers them?
> Are you trying to improve performance?  If so, do you have any data
> demonstrating that it benefits some workload?

In 0/7 he says, "By moving the current HiZ/color resolves
we need before drawing from out of the notify and into the draw itself,
we can save a few percent of overhead in OglBatch7 on Atom class
devices."  Given the amount of change here, I too would like to see some
actual performance data.

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