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intel/perf: simplify the processing of OA reports 

This is a more accurate description of what happens in processing the
OA reports.

Previously we only had a somewhat difficult to parse state machine
tracking the context ID.

What we really only need to do to decide if the delta between 2
reports (r0 & r1) should be accumulated in the query result is :

   * whether the r0 is tagged with the context ID relevant to us

   * if r0 is not tagged with our context ID and r1 is: does r0 have a
     invalid context id? If not then we're in a case where i915 has
     resubmitted the same context for execution through the execlist
     submission port

v2: Update comment (Ken)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Lionel Landwerlin 2019-12-03 16:33:25 +02:00
parent b364e920bf
commit 8c0b058263
1 changed files with 36 additions and 28 deletions
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64
src/intel/perf/gen_perf.c
View File

@ -2221,6 +2221,17 @@ discard_all_queries(struct gen_perf_context *perf_ctx)
}
}
/* Looks for the validity bit of context ID (dword 2) of an OA report. */
static bool
oa_report_ctx_id_valid(const struct gen_device_info *devinfo,
const uint32_t *report)
{
assert(devinfo->gen >= 8);
if (devinfo->gen == 8)
return (report[0] & (1 << 25)) != 0;
return (report[0] & (1 << 16)) != 0;
}
/**
* Accumulate raw OA counter values based on deltas between pairs of
* OA reports.
@ -2248,7 +2259,7 @@ accumulate_oa_reports(struct gen_perf_context *perf_ctx,
uint32_t *last;
uint32_t *end;
struct exec_node *first_samples_node;
bool in_ctx = true;
bool last_report_ctx_match = true;
int out_duration = 0;
assert(query->oa.map != NULL);
@ -2302,6 +2313,7 @@ accumulate_oa_reports(struct gen_perf_context *perf_ctx,
switch (header->type) {
case DRM_I915_PERF_RECORD_SAMPLE: {
uint32_t *report = (uint32_t *)(header + 1);
bool report_ctx_match = true;
bool add = true;
/* Ignore reports that come before the start marker.
@ -2330,35 +2342,30 @@ accumulate_oa_reports(struct gen_perf_context *perf_ctx,
* of OA counters while any other context is acctive.
*/
if (devinfo->gen >= 8) {
if (in_ctx && report[2] != query->oa.result.hw_id) {
DBG("i915 perf: Switch AWAY (observed by ID change)\n");
in_ctx = false;
/* Consider that the current report matches our context only if
* the report says the report ID is valid.
*/
report_ctx_match = oa_report_ctx_id_valid(devinfo, report) &&
report[2] == start[2];
if (report_ctx_match)
out_duration = 0;
} else if (in_ctx == false && report[2] == query->oa.result.hw_id) {
DBG("i915 perf: Switch TO\n");
in_ctx = true;
/* From experimentation in IGT, we found that the OA unit
* might label some report as "idle" (using an invalid
* context ID), right after a report for a given context.
* Deltas generated by those reports actually belong to the
* previous context, even though they're not labelled as
* such.
*
* We didn't *really* Switch AWAY in the case that we e.g.
* saw a single periodic report while idle...
*/
if (out_duration >= 1)
add = false;
} else if (in_ctx) {
assert(report[2] == query->oa.result.hw_id);
DBG("i915 perf: Continuation IN\n");
} else {
assert(report[2] != query->oa.result.hw_id);
DBG("i915 perf: Continuation OUT\n");
add = false;
else
out_duration++;
}
/* Only add the delta between <last, report> if the last report
* was clearly identified as our context, or if we have at most
* 1 report without a matching ID.
*
* The OA unit will sometimes label reports with an invalid
* context ID when i915 rewrites the execlist submit register
* with the same context as the one currently running. This
* happens when i915 wants to notify the HW of ringbuffer tail
* register update. We have to consider this report as part of
* our context as the 3d pipeline behind the OACS unit is still
* processing the operations started at the previous execlist
* submission.
*/
add = last_report_ctx_match && out_duration < 2;
}
if (add) {
@ -2368,6 +2375,7 @@ accumulate_oa_reports(struct gen_perf_context *perf_ctx,
}
last = report;
last_report_ctx_match = report_ctx_match;
break;
}