[Mesa-dev] [PATCH v2 3/5] i965: perf: read slice/unslice frequencies from OA reports

[Kenneth Graunke]

On Tuesday, April 3, 2018 7:48:11 AM PDT Lionel Landwerlin wrote:
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>  src/mesa/drivers/dri/i965/brw_performance_query.c | 37 +++++++++++++++++++++++
>  src/mesa/drivers/dri/i965/brw_performance_query.h | 12 ++++++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_performance_query.c b/src/mesa/drivers/dri/i965/brw_performance_query.c
> index 32cf96a333d..d20bc58ee33 100644
> --- a/src/mesa/drivers/dri/i965/brw_performance_query.c
> +++ b/src/mesa/drivers/dri/i965/brw_performance_query.c
> @@ -1341,6 +1341,42 @@ brw_is_perf_query_ready(struct gl_context *ctx,
>     return false;
>  }
>  
> +static void
> +gen8_read_report_clock_ratios(const uint32_t *report,
> +                              uint64_t *slice_freq_hz,
> +                              uint64_t *unslice_freq_hz)
> +{
> +   uint32_t unslice_freq = report[0] & 0x1ff;
> +   uint32_t slice_freq_low = (report[0] >> 25) & 0x7f;
> +   uint32_t slice_freq_high = (report[0] >> 9) & 0x3;
> +   uint32_t slice_freq = slice_freq_low | (slice_freq_high << 7);
> +
> +   *slice_freq_hz = slice_freq * 16666000ULL;
> +   *unslice_freq_hz = unslice_freq * 16666000ULL;

What is this reading?  Could we add a comment to the function?
Otherwise, I'm not sure where to even begin to look for this in docs.

> +}
> +
> +static void
> +read_slice_unslice_frequencies(struct brw_context *brw,
> +                               struct brw_perf_query_object *obj)
> +{
> +   const struct gen_device_info *devinfo = &brw->screen->devinfo;
> +   uint32_t *begin_report, *end_report;
> +
> +   /* No data available before gen8. */
> +   if (devinfo->gen < 8)
> +      return;
> +
> +   begin_report = obj->oa.map;
> +   end_report = obj->oa.map + MI_RPC_BO_END_OFFSET_BYTES;

I'm probably missing something obvious here, but...this looks fishy.

What actually writes these values to the OA buffer?  And here, you're
reading the starting value from DWord 0 of the buffer...is that really
where those values live?

I guess I would have expected to see a capture_uncore_frequencies()
and MI_SLICE_FREQ_START_OFFSET_BYTES or something, like patch 2/5 does.

> +
> +   gen8_read_report_clock_ratios(begin_report,
> +                                 &obj->oa.slice_frequency[0],
> +                                 &obj->oa.unslice_frequency[0]);
> +   gen8_read_report_clock_ratios(end_report,
> +                                 &obj->oa.slice_frequency[1],
> +                                 &obj->oa.unslice_frequency[1]);
> +}
> +
>  static void
>  read_gt_frequency(struct brw_context *brw,
>                    struct brw_perf_query_object *obj)
> @@ -1382,6 +1418,7 @@ get_oa_counter_data(struct brw_context *brw,
>  
>     if (!obj->oa.results_accumulated) {
>        read_gt_frequency(brw, obj);
> +      read_slice_unslice_frequencies(brw, obj);
>        accumulate_oa_reports(brw, obj);
>        assert(obj->oa.results_accumulated);
>  
> diff --git a/src/mesa/drivers/dri/i965/brw_performance_query.h b/src/mesa/drivers/dri/i965/brw_performance_query.h
> index f8732738b4e..6d3ecf0be3a 100644
> --- a/src/mesa/drivers/dri/i965/brw_performance_query.h
> +++ b/src/mesa/drivers/dri/i965/brw_performance_query.h
> @@ -118,6 +118,18 @@ struct brw_perf_query_object
>            * Frequency of the GT at begin and end of the query.
>            */
>           uint64_t gt_frequency[2];
> +
> +         /**
> +          * Frequency in the the slices of the GT at the begin and end of the
> +          * query.
> +          */
> +         uint64_t slice_frequency[2];
> +
> +         /**
> +          * Frequency in the the unslice of the GT at the begin and end of the
> +          * query.
> +          */
> +         uint64_t unslice_frequency[2];
>        } oa;
>  
>        struct {
> 

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