Quoting Sagar Arun Kamble (2017-07-31 08:59:36)
> +/**
> + * i915_perf_stream_emit_sample_capture - Insert the commands to capture perf
> + * metrics into the GPU command stream
> + * @stream: An i915-perf stream opened for GPU metrics
> + * @request: request in whose context the metrics are being collected.
> + * @preallocate: allocate space in ring for related sample.
> + */
> +static void i915_perf_stream_emit_sample_capture(
> + struct i915_perf_stream *stream,
> + struct drm_i915_gem_request *request,
> + bool preallocate)
> +{
> + struct reservation_object *resv = stream->cs_buffer.vma->resv;
> + struct i915_perf_cs_sample *sample;
> + unsigned long flags;
> + int ret;
> +
> + sample = kzalloc(sizeof(*sample), GFP_KERNEL);
> + if (sample == NULL) {
> + DRM_ERROR("Perf sample alloc failed\n");
> + return;
> + }
> +
> + sample->request = i915_gem_request_get(request);
> + sample->ctx_id = request->ctx->hw_id;
> +
> + insert_perf_sample(stream, sample);
> +
> + if (stream->sample_flags & SAMPLE_OA_REPORT) {
> + ret = i915_emit_oa_report_capture(request,
> + preallocate,
> + sample->offset);
> + if (ret)
> + goto err_unref;
> + }
This is incorrect as the requests may be reordered. You either need to
declare the linear ordering of requests through the sample buffer, or we
have to delay setting sample->offset until execution, and even then we
need to disable preemption when using SAMPLE_OA_REPORT.
-Chris
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