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i965: Ignore reloc read/write domains

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Since before the kernel supported I915_EXEC_NO_RELOC, long before our
minimum kernel requirement, the kernel unconditionally invalidated all
GPU TLBs before a batch and flushed all GPU caches after a batch. At
that moment, the only use for read/write domain was for activity
tracking, ensuring that future reads waited for the last writer and
future writes waited for all reads. This only requires a single bit in
the execbuf interface which can be supplied via the NO_RELOC interface,
making the use of relocation domains entirely redundant.

Trimming the excess writes into the array allows the compiler to be much
more frugal:

   text	   data	    bss	    dec	    hex	filename
8493790	 357184	 424944	9275918	 8d8a0e	i965_dri.baseline
8493758	 357184	 424944	9275886	 8d89ee	i965_dri.so

(This text improvement really does come from dropping domains, not from
the new use of C99 initializers.)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Chris Wilson 2017-07-21 16:36:48 +01:00 • committed by Kenneth Graunke
parent 3f353342a6
commit ba9b71e56a
1 changed files with 7 additions and 11 deletions
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18
src/mesa/drivers/dri/i965/intel_batchbuffer.c
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@ -811,17 +811,13 @@ brw_emit_reloc(struct intel_batchbuffer *batch, uint32_t batch_offset,
offset64 = target->offset64;
}
struct drm_i915_gem_relocation_entry *reloc =
&batch->relocs[batch->reloc_count];
batch->reloc_count++;
reloc->offset = batch_offset;
reloc->delta = target_offset;
reloc->target_handle = target->gem_handle;
reloc->read_domains = read_domains;
reloc->write_domain = write_domain;
reloc->presumed_offset = offset64;
batch->relocs[batch->reloc_count++] =
(struct drm_i915_gem_relocation_entry) {
.offset = batch_offset,
.delta = target_offset,
.target_handle = target->gem_handle,
.presumed_offset = offset64,
};
/* Using the old buffer offset, write in what the right data would be, in
* case the buffer doesn't move and we can short-circuit the relocation