[Intel-gfx] [RFC 0/8] Force preemption

[jeff.mcgee at intel.com]

From: Jeff McGee <jeff.mcgee at intel.com>

Force preemption uses engine reset to enforce a limit on the time
that a request targeted for preemption can block. This feature is
a requirement in automotive systems where the GPU may be shared by
clients of critically high priority and clients of low priority that
may not have been curated to be preemption friendly. There may be
more general applications of this feature. I'm sharing as an RFC to
stimulate that discussion and also to get any technical feedback
that I can before submitting to the product kernel that needs this.
I have developed the patches for ease of rebase, given that this is
for the moment considered a non-upstreamable feature. It would be
possible to refactor hangcheck to fully incorporate force preemption
as another tier of patience (or impatience) with the running request.

Jeff McGee (8):
  drm/i915: Downgrade tasklet GEM_BUG_ON for request not completed
  drm/i915: Skip CSB processing on invalid CSB tail
  drm/i915: Execlists to mark the HWSP upon preemption finished
  drm/i915: Add a wait_for routine with more exact timeout
  drm/i915: Consider preemption when finding the active request
  drm/i915: Repair the preemption context if hit by reset
  drm/i915: Allow reset without error capture
  drm/i915: Force preemption to complete via engine reset

 drivers/gpu/drm/i915/i915_drv.c         | 14 +++++-
 drivers/gpu/drm/i915/i915_drv.h         |  4 ++
 drivers/gpu/drm/i915/i915_gem.c         | 86 ++++++++++++++++++++++++++++++---
 drivers/gpu/drm/i915/i915_irq.c         | 75 ++++++++++++++++------------
 drivers/gpu/drm/i915/i915_params.c      |  3 ++
 drivers/gpu/drm/i915/i915_params.h      |  1 +
 drivers/gpu/drm/i915/intel_drv.h        | 22 +++++++++
 drivers/gpu/drm/i915/intel_engine_cs.c  | 53 ++++++++++++++++++++
 drivers/gpu/drm/i915/intel_lrc.c        | 81 +++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/intel_ringbuffer.h | 20 +++++++-
 10 files changed, 314 insertions(+), 45 deletions(-)

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2.16.2