Re: [PATCH 00/55] Remove the outstanding_lazy_request

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, May 29, 2015 at 05:43:21PM +0100, John.C.Harrison@Intel.com wrote:
> From: John Harrison <John.C.Harrison@Intel.com>
> 
> The driver tracks GPU work using request structures. Unfortunately, this
> tracking is not currently explicit but is done by means of a catch-all request
> that floats around in the background hoovering up work until it gets submitted.
> This background request (ring->outstanding_lazy_request or OLR) is created at
> the point of actually writing to the ring rather than when a particular piece of
> GPU work is started. This scheme sort of hangs together but causes a number of
> issues. It can mean that multiple pieces of independent work are lumped together
> in the same request or that work is not officially submitted until much later
> than it was created.
> 
> This patch series completely removes the OLR and explicitly tracks each piece of
> work with it's own personal request structure from start to submission.
> 
> The patch set seems to fix the "'gem_ringfill --r render' + ctrl-c straight
> after boot" issue logged as BZ:88865. I haven't done any analysis of that
> particular issue but the descriptions I've seen appear to blame an inconsistent
> or mangled OLR.
> 
> Note also that by the end of this series, a number of differences between the
> legacy and execlist code paths have been removed. For example add_request() and
> emit_request() now have the same signature thus could be merged back to a single
> function pointer. Merging some of these together would also allow the removal of
> a bunch of 'if(execlists)' tests where the difference is simply to call the
> legacy function or the execlist one.
> 
> v2: Rebased to newer nightly tree, fixed up a few minor issues, added two extra
> patches - one to move the LRC ring begin around in the vein of other recent
> reshuffles, the other to clean up some issues with i915_add_request().
> 
> v3: Large re-work due to feedback from code review. Some patches have been
> removed, extra ones have been added and others have been changed significantly.
> It is recommended that all patches are reviewed from scratch rather than
> assuming only certain ones have changed and need re-inspecting. The exceptions
> are where the 'reviewed-by' tag has been kept because that patch was not
> significantly affected.
> 
> v4: Further updates due to review feedback and rebasing on top of significant
> changes to the underlying tree.
> 
> [Patches against drm-intel-nightly tree fetched 22/05/2015]
> 
> John Harrison (55):
>   drm/i915: Re-instate request->uniq becuase it is extremely useful
>   drm/i915: Reserve ring buffer space for i915_add_request() commands
>   drm/i915: i915_add_request must not fail
>   drm/i915: Early alloc request in execbuff
>   drm/i915: Set context in request from creation even in legacy mode
>   drm/i915: Merged the many do_execbuf() parameters into a structure
>   drm/i915: Simplify i915_gem_execbuffer_retire_commands() parameters
>   drm/i915: Update alloc_request to return the allocated request
>   drm/i915: Add request to execbuf params and add explicit cleanup
>   drm/i915: Update the dispatch tracepoint to use params->request
>   drm/i915: Update move_to_gpu() to take a request structure
>   drm/i915: Update execbuffer_move_to_active() to take a request structure
>   drm/i915: Add flag to i915_add_request() to skip the cache flush
>   drm/i915: Update i915_gpu_idle() to manage its own request
>   drm/i915: Split i915_ppgtt_init_hw() in half - generic and per ring
>   drm/i915: Moved the for_each_ring loop outside of i915_gem_context_enable()
>   drm/i915: Don't tag kernel batches as user batches
>   drm/i915: Add explicit request management to i915_gem_init_hw()
>   drm/i915: Update ppgtt_init_ring() & context_enable() to take requests
>   drm/i915: Update i915_switch_context() to take a request structure
>   drm/i915: Update do_switch() to take a request structure
>   drm/i915: Update deferred context creation to do explicit request management
>   drm/i915: Update init_context() to take a request structure
>   drm/i915: Update render_state_init() to take a request structure
>   drm/i915: Update i915_gem_object_sync() to take a request structure
>   drm/i915: Update overlay code to do explicit request management
>   drm/i915: Update queue_flip() to take a request structure
>   drm/i915: Update add_request() to take a request structure
>   drm/i915: Update [vma|object]_move_to_active() to take request structures
>   drm/i915: Update l3_remap to take a request structure
>   drm/i915: Update mi_set_context() to take a request structure
>   drm/i915: Update a bunch of execbuffer helpers to take request structures
>   drm/i915: Update workarounds_emit() to take request structures
>   drm/i915: Update flush_all_caches() to take request structures
>   drm/i915: Update switch_mm() to take a request structure
>   drm/i915: Update ring->flush() to take a requests structure
>   drm/i915: Update some flush helpers to take request structures
>   drm/i915: Update ring->emit_flush() to take a request structure
>   drm/i915: Update ring->add_request() to take a request structure
>   drm/i915: Update ring->emit_request() to take a request structure
>   drm/i915: Update ring->dispatch_execbuffer() to take a request structure
>   drm/i915: Update ring->emit_bb_start() to take a request structure
>   drm/i915: Update ring->sync_to() to take a request structure
>   drm/i915: Update ring->signal() to take a request structure
>   drm/i915: Update cacheline_align() to take a request structure
>   drm/i915: Update intel_ring_begin() to take a request structure
>   drm/i915: Update intel_logical_ring_begin() to take a request structure
>   drm/i915: Add *_ring_begin() to request allocation
>   drm/i915: Remove the now obsolete intel_ring_get_request()
>   drm/i915: Remove the now obsolete 'outstanding_lazy_request'
>   drm/i915: Move the request/file and request/pid association to creation time
>   drm/i915: Remove 'faked' request from LRC submission
>   drm/i915: Update a bunch of LRC functions to take requests
>   drm/i915: Remove the now obsolete 'i915_gem_check_olr()'
>   drm/i915: Rename the somewhat reduced i915_gem_object_flush_active()

Applied the entire series except patch 1 (we seem to have managed making
tracepoints abi and I'm chickening out of this, or well don't want to
block the olr removal on it and so rebased a few patches that conflicted).
And the last two since the very last is superseeded and the second last
seems to not deconfuse with the new function names after read/read.

Thanks, Daniel

> 
>  drivers/gpu/drm/i915/i915_drv.h              |   77 +++---
>  drivers/gpu/drm/i915/i915_gem.c              |  368 ++++++++++++++++----------
>  drivers/gpu/drm/i915/i915_gem_context.c      |   78 +++---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c   |  128 +++++----
>  drivers/gpu/drm/i915/i915_gem_gtt.c          |   59 +++--
>  drivers/gpu/drm/i915/i915_gem_gtt.h          |    3 +-
>  drivers/gpu/drm/i915/i915_gem_render_state.c |   15 +-
>  drivers/gpu/drm/i915/i915_gem_render_state.h |    2 +-
>  drivers/gpu/drm/i915/i915_trace.h            |   41 +--
>  drivers/gpu/drm/i915/intel_display.c         |   60 +++--
>  drivers/gpu/drm/i915/intel_drv.h             |    3 +-
>  drivers/gpu/drm/i915/intel_fbdev.c           |    2 +-
>  drivers/gpu/drm/i915/intel_lrc.c             |  265 +++++++++----------
>  drivers/gpu/drm/i915/intel_lrc.h             |   16 +-
>  drivers/gpu/drm/i915/intel_overlay.c         |   63 +++--
>  drivers/gpu/drm/i915/intel_ringbuffer.c      |  303 +++++++++++++--------
>  drivers/gpu/drm/i915/intel_ringbuffer.h      |   53 ++--
>  17 files changed, 876 insertions(+), 660 deletions(-)
> 
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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