[Mesa-dev] [PATCH 8/9] radeonsi: don't emit partial flushes at the end of IBs

[Nicolai Hähnle]

On 16.06.2017 14:58, Marek Olšák wrote:
> From: Marek Olšák <marek.olsak at amd.com>
> 
> The kernel sort of does the same thing with fences.

The kernel sends an EVENT_WRITE_EOP with various TC flags. Is that 
guaranteed to wait for shaders to finish and flush their data? I'm 
mostly thinking about synchronizing with CPU reads here.

While reading, I noticed that si_emit_cache_flush has a path where L1 is 
invalidated _after_ L2 writeback. What's up with that? Couldn't it 
happen that there's data in L1 which is not yet written to L2? Seems odd.

Cheers,
Nicolai


> ---
>   src/gallium/drivers/radeonsi/si_hw_context.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/src/gallium/drivers/radeonsi/si_hw_context.c b/src/gallium/drivers/radeonsi/si_hw_context.c
> index 345825a..5d930a6 100644
> --- a/src/gallium/drivers/radeonsi/si_hw_context.c
> +++ b/src/gallium/drivers/radeonsi/si_hw_context.c
> @@ -122,27 +122,27 @@ void si_context_gfx_flush(void *context, unsigned flags,
>   	}
>   
>   	ctx->gfx_flush_in_progress = true;
>   
>   	/* This CE dump should be done in parallel with the last draw. */
>   	if (ctx->ce_ib)
>   		si_ce_save_all_descriptors_at_ib_end(ctx);
>   
>   	r600_preflush_suspend_features(&ctx->b);
>   
> -	ctx->b.flags |= SI_CONTEXT_CS_PARTIAL_FLUSH |
> -			SI_CONTEXT_PS_PARTIAL_FLUSH;
> -
>   	/* DRM 3.1.0 doesn't flush TC for VI correctly. */
> -	if (ctx->b.chip_class == VI && ctx->b.screen->info.drm_minor <= 1)
> -		ctx->b.flags |= SI_CONTEXT_INV_GLOBAL_L2 |
> +	if (ctx->b.chip_class == VI && ctx->b.screen->info.drm_minor <= 1) {
> +		ctx->b.flags |= SI_CONTEXT_PS_PARTIAL_FLUSH |
> +				SI_CONTEXT_CS_PARTIAL_FLUSH |
> +				SI_CONTEXT_INV_GLOBAL_L2 |
>   				SI_CONTEXT_INV_VMEM_L1;
> +	}
>   
>   	si_emit_cache_flush(ctx);
>   
>   	if (ctx->trace_buf)
>   		si_trace_emit(ctx);
>   
>   	if (ctx->is_debug) {
>   		/* Save the IB for debug contexts. */
>   		radeon_clear_saved_cs(&ctx->last_gfx);
>   		radeon_save_cs(ws, cs, &ctx->last_gfx);
> 


-- 
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.