Re: [PATCH v2 2/3] drm/i915/perf: enable OAR context save/restore of performance counters

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

On 18/10/2019 03:50, Umesh Nerlige Ramappa wrote:
> From: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
>
> We want this so we can preempt performance queries and keep the system
> responsive even when long running queries are ongoing. We avoid doing
> it for all contexts.
>
> v2: use LRI to modify context control (Chris)
> v3: use MASKED_FIELD to program just the masked bits (Chris)
> v4: reuse request created during emit_oa_config (Lionel)
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>


Looks good :


Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>


> ---
>   drivers/gpu/drm/i915/gt/intel_lrc.h |  1 +
>   drivers/gpu/drm/i915/i915_perf.c    | 35 ++++++++++++++++++++++++++++-
>   2 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.h b/drivers/gpu/drm/i915/gt/intel_lrc.h
> index 99dc576a4e25..b6daac712c9e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.h
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.h
> @@ -43,6 +43,7 @@ struct intel_engine_cs;
>   #define	  CTX_CTRL_ENGINE_CTX_RESTORE_INHIBIT	(1 << 0)
>   #define   CTX_CTRL_RS_CTX_ENABLE		(1 << 1)
>   #define	  CTX_CTRL_ENGINE_CTX_SAVE_INHIBIT	(1 << 2)
> +#define	  GEN12_CTX_CTRL_OAR_CONTEXT_ENABLE	(1 << 8)
>   #define RING_CONTEXT_STATUS_PTR(base)		_MMIO((base) + 0x3a0)
>   #define RING_EXECLIST_SQ_CONTENTS(base)		_MMIO((base) + 0x510)
>   #define RING_EXECLIST_CONTROL(base)		_MMIO((base) + 0x550)
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 91707558a0f5..ce97af484a32 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -1862,14 +1862,36 @@ get_oa_vma(struct i915_perf_stream *stream, struct i915_oa_config *oa_config)
>   	return i915_vma_get(oa_bo->vma);
>   }
>   
> +static int gen12_emit_oar_config(struct i915_request *rq,
> +				 struct intel_context *ce,
> +				 bool enable)
> +{
> +	u32 *cs;
> +
> +	cs = intel_ring_begin(rq, 4);
> +	if (IS_ERR(cs))
> +		return PTR_ERR(cs);
> +
> +	*cs++ = MI_LOAD_REGISTER_IMM(1);
> +	*cs++ = i915_mmio_reg_offset(RING_CONTEXT_CONTROL(ce->engine->mmio_base));
> +	*cs++ = _MASKED_FIELD(GEN12_CTX_CTRL_OAR_CONTEXT_ENABLE,
> +			      enable ? GEN12_CTX_CTRL_OAR_CONTEXT_ENABLE : 0);
> +	*cs++ = MI_NOOP;
> +
> +	intel_ring_advance(rq, cs);
> +
> +	return 0;
> +}
> +
>   static int emit_oa_config(struct i915_perf_stream *stream,
>   			  struct intel_context *ce)
>   {
> +	struct i915_oa_config *oa_config = stream->oa_config;
>   	struct i915_request *rq;
>   	struct i915_vma *vma;
>   	int err;
>   
> -	vma = get_oa_vma(stream, stream->oa_config);
> +	vma = get_oa_vma(stream, oa_config);
>   	if (IS_ERR(vma))
>   		return PTR_ERR(vma);
>   
> @@ -1891,6 +1913,17 @@ static int emit_oa_config(struct i915_perf_stream *stream,
>   	if (err)
>   		goto err_add_request;
>   
> +	/*
> +	 * For Gen12, performance counters are context saved/restored.
> +	 * Only enable it for the context that requested this.
> +	 */
> +	if (ce == stream->pinned_ctx && IS_GEN(stream->perf->i915, 12)) {
> +		err = gen12_emit_oar_config(rq, ce, oa_config != NULL);
> +		if (err)
> +			goto err_add_request;
> +
> +	}
> +
>   	err = rq->engine->emit_bb_start(rq,
>   					vma->node.start, 0,
>   					I915_DISPATCH_SECURE);


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