On Wed, Nov 25, 2015 at 11:37 AM, Francisco Jerez <curroje...@riseup.net> wrote:
> The thread scratch space is thread-local so using the full IA-coherent
> stateless surface index (255 since Gen8) is unnecessary and
> potentially expensive. On Gen8 and early steppings of Gen9 this is
> not a functional change because the kernel already sets bit 4 of
> HDC_CHICKEN0 which overrides all HDC memory access to be non-coherent
> in order to workaround a hardware bug.
>
> This happens to fix a full system hang when running any spilling code
> on a pre-production SKL GT4e machine I have on my desk (forcing all
> HDC access to non-coherent from the kernel up to stepping F0 might be
> a good idea though regardless of this patch), and improves performance
> of the OglPSBump2 SynMark benchmark run with INTEL_DEBUG=spill_fs by
> 33% (11 runs, 5% significance) on a production SKL GT2 (on which HDC
> IA-coherency is apparently functional so it wouldn't make sense to
> disable globally).
Very nice, all looks good to me. All three patches:
Reviewed-by: Kristian Høgsberg <k...@bitplanet.net>
> ---
> src/mesa/drivers/dri/i965/brw_eu.h | 2 ++
> src/mesa/drivers/dri/i965/brw_eu_emit.c | 17 +++++++++++++++--
> src/mesa/drivers/dri/i965/brw_vec4_generator.cpp | 4 ++--
> 3 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_eu.h
> b/src/mesa/drivers/dri/i965/brw_eu.h
> index 829e393..62891c7 100644
> --- a/src/mesa/drivers/dri/i965/brw_eu.h
> +++ b/src/mesa/drivers/dri/i965/brw_eu.h
> @@ -317,6 +317,8 @@ void brw_oword_block_read(struct brw_codegen *p,
> uint32_t offset,
> uint32_t bind_table_index);
>
> +unsigned brw_scratch_surface_idx(const struct brw_codegen *p);
> +
> void brw_oword_block_read_scratch(struct brw_codegen *p,
> struct brw_reg dest,
> struct brw_reg mrf,
> diff --git a/src/mesa/drivers/dri/i965/brw_eu_emit.c
> b/src/mesa/drivers/dri/i965/brw_eu_emit.c
> index da1ddfd..bb6f5dc 100644
> --- a/src/mesa/drivers/dri/i965/brw_eu_emit.c
> +++ b/src/mesa/drivers/dri/i965/brw_eu_emit.c
> @@ -1997,6 +1997,19 @@ void gen6_math(struct brw_codegen *p,
> brw_set_src1(p, insn, src1);
> }
>
> +/**
> + * Return the right surface index to access the thread scratch space using
> + * stateless dataport messages.
> + */
> +unsigned
> +brw_scratch_surface_idx(const struct brw_codegen *p)
> +{
> + /* The scratch space is thread-local so IA coherency is unnecessary. */
> + if (p->devinfo->gen >= 8)
> + return GEN8_BTI_STATELESS_NON_COHERENT;
> + else
> + return BRW_BTI_STATELESS;
> +}
>
> /**
> * Write a block of OWORDs (half a GRF each) from the scratch buffer,
> @@ -2097,7 +2110,7 @@ void brw_oword_block_write_scratch(struct brw_codegen
> *p,
>
> brw_set_dp_write_message(p,
> insn,
> - 255, /* binding table index (255=stateless) */
> + brw_scratch_surface_idx(p),
> msg_control,
> msg_type,
> mlen,
> @@ -2183,7 +2196,7 @@ brw_oword_block_read_scratch(struct brw_codegen *p,
>
> brw_set_dp_read_message(p,
> insn,
> - 255, /* binding table index (255=stateless) */
> + brw_scratch_surface_idx(p),
> msg_control,
> BRW_DATAPORT_READ_MESSAGE_OWORD_BLOCK_READ, /*
> msg_type */
> BRW_DATAPORT_READ_TARGET_RENDER_CACHE,
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> index 20107ac..65b4358 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_generator.cpp
> @@ -800,7 +800,7 @@ generate_scratch_read(struct brw_codegen *p,
> if (devinfo->gen < 6)
> brw_inst_set_cond_modifier(devinfo, send, inst->base_mrf);
> brw_set_dp_read_message(p, send,
> - 255, /* binding table index: stateless access */
> + brw_scratch_surface_idx(p),
> BRW_DATAPORT_OWORD_DUAL_BLOCK_1OWORD,
> msg_type,
> BRW_DATAPORT_READ_TARGET_RENDER_CACHE,
> @@ -873,7 +873,7 @@ generate_scratch_write(struct brw_codegen *p,
> if (devinfo->gen < 6)
> brw_inst_set_cond_modifier(p->devinfo, send, inst->base_mrf);
> brw_set_dp_write_message(p, send,
> - 255, /* binding table index: stateless access */
> + brw_scratch_surface_idx(p),
> BRW_DATAPORT_OWORD_DUAL_BLOCK_1OWORD,
> msg_type,
> 3, /* mlen */
> --
> 2.5.1
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/mesa-dev
