[Intel-gfx] [RFC 0/7] Introduce framework for forwarding generic non-OA performance

[sourab.gupta at intel.com]

From: Sourab Gupta <sourab.gupta at intel.com>

Cc: Robert Bragg <robert at sixbynine.org>,
    Zhenyu Wang <zhenyuw at linux.intel.com>,
    Jon Bloomfield <jon.bloomfield at intel.com>,
    Peter Zijlstra <a.p.zijlstra at chello.nl>,
    Jabin Wu <jabin.wu at intel.com>,
    Insoo Woo <insoo.woo at intel.com>


This patch series builds upon the initial patch set floated earlier which
extends the periodic OA sampling framework and adds handling asynchronous OA
counter data and forwards the samples using perf. This series can be seen at:

http://lists.freedesktop.org/archives/intel-gfx/2015-June/069263.html

The OA unit, as such, is specific to render ring and can't cater to performance
data requirements for other GPU engines.
Specifically, the media workloads may utilize other GPU engines, but there is
currently no framework which can be used to query performance statistics for
non-RCS workloads and provide this data to userspace tools. This patch set
tries to address this specific problem. The aim of this patch series is to
build upon the perf event framework developed earlier and use it for
forwarding performance data of non-RCS engine workloads.

Since the previous PMU is customized to handle OA reports, a new perf PMU is
added to handle generic non-OA performance data. An example of such non-OA
performance data is the timestamps captured at asynchronous points during
workload execution.
This patch set makes this specific further by capturing the timestamps at
batch buffer boundaries, by inserting commands for the same in ringbuffer,
and forwarding the samples to userspace through perf interface.
Nevertheless, the framework and data structures can be extended to introduce
more performance data types (other than timestamps) and capture these at other 
points of workload execution. The intention here is to introduce a framework
to enable capturing of generic performance data and forwarding the same to
userspace using perf apis.

The reports generated will again have an additional footer for metadata
information such as ctx_id, pid, ring id and tags (in the same way as done
for OA reports specified in the patch series earlier). This information can be
used by userspace tools such as MVP (Modular Video Profiler) to associate
reports with individual contexts and different stages of workload execution.

In this patch set, the timestamps are captured at BB boundaries by inserting
the commands in the ringbuffer at the batchbuffer boundaries. As specified
earlier, for a system wide GPU profiler, the relative complexity of doing this
in kernel is significantly less than supporting this usecase through userspace
command insertion by all the different components.

The final patch in the series tries to extend the data structures to enable
capture of upto 8 MMIO register values, in conjunction with timestamps


Sourab Gupta (7):
  drm/i915: Add a new PMU for handling non-OA counter data profiling
    requests
  drm/i915: Register routines for Gen perf PMU driver
  drm/i915: Introduce timestamp node for timestamp data collection
  drm/i915: Add mechanism for forwarding the data samples to userspace
    through Gen PMU perf interface
  drm/i915: Wait for GPU to finish before event stop in Gen Perf PMU
  drm/i915: Add routines for inserting commands in the ringbuf for
    capturing timestamps
  drm/i915: Add support for retrieving MMIO register values in Gen Perf
    PMU

 drivers/gpu/drm/i915/i915_dma.c     |   2 +
 drivers/gpu/drm/i915/i915_drv.h     |  47 +++
 drivers/gpu/drm/i915/i915_oa_perf.c | 579 ++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_reg.h     |   2 +
 include/uapi/drm/i915_drm.h         |  25 ++
 5 files changed, 655 insertions(+)

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1.8.5.1