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i965: Account for poor address calculations in Haswell CS scratch size.

Browse source 
Curro figured this out by investigating the simulator.  Apparently
there's also a workaround in the Windows driver.  I'm not sure it's
actually documented anywhere.

We were underallocating the scratch buffer by a factor of 128/70.

v2: Rename threads_per_subslice to scratch_ids_per_subslice
    (suggested by Jordan Justen).

Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
(cherry picked from commit a7d029d3df)
This commit is contained in:
Kenneth Graunke 2016-06-09 16:11:46 -07:00 • committed by Emil Velikov
parent 6c5c1bc1b9
commit e84116f364
1 changed files with 20 additions and 1 deletions
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21
src/mesa/drivers/dri/i965/brw_cs.c
View file

@ -150,9 +150,28 @@ brw_codegen_cs_prog(struct brw_context *brw,
if (prog_data.base.total_scratch) {
const unsigned subslices = MAX2(brw->intelScreen->subslice_total, 1);
/* WaCSScratchSize:hsw
*
* Haswell's scratch space address calculation appears to be sparse
* rather than tightly packed. The Thread ID has bits indicating
* which subslice, EU within a subslice, and thread within an EU
* it is. There's a maximum of two slices and two subslices, so these
* can be stored with a single bit. Even though there are only 10 EUs
* per subslice, this is stored in 4 bits, so there's an effective
* maximum value of 16 EUs. Similarly, although there are only 7
* threads per EU, this is stored in a 3 bit number, giving an effective
* maximum value of 8 threads per EU.
*
* This means that we need to use 16 * 8 instead of 10 * 7 for the
* number of threads per subslice.
*/
const unsigned scratch_ids_per_subslice =
brw->is_haswell ? 16 * 8 : brw->max_cs_threads;
brw_get_scratch_bo(brw, &brw->cs.base.scratch_bo,
prog_data.base.total_scratch *
brw->max_cs_threads * subslices);
scratch_ids_per_subslice * subslices);
}
if (unlikely(INTEL_DEBUG & DEBUG_CS))