[igt-dev] [PATCH i-g-t 00/79] Stop depending on context mutation (v4)

Jason Ekstrand jason at jlekstrand.net
Thu Jun 17 19:12:07 UTC 2021


I'm trying to clean up some of our uAPI technical debt in i915.  One of the
biggest areas we have right now is context mutability.  There's no good
reason why things like the set of engines or the VM should be able to be
changed on the fly and no "real" userspace actually relies on this
functionality.  It does, however, make for a good excuse for tests and lots
of bug reports as things like swapping out the set of engines under load
break randomly.  The solution here is to stop allowing that behavior and
simplify the i915 internals.

In particular, we'd like to remove the following from the i915 API:

 1. I915_CONTEXT_CLONE_*.  These are only used by IGT and have never been
    used by any "real" userspace.

 2. Changing the VM or set of engines via SETPARAM after they've been
    "used" by an execbuf or similar.  This would effectively make those
    parameters create params rather than mutable state.  We can't drop
    setparam entirely for those because media does use it but we can
    enforce some rules.

 3. Unused (by non-IGT userspace) GETPARAM for things like engines.

As much as we'd love to do that, we have a bit of a problem in IGT.  The
way we handle multi-engine testing today relies heavily on this soon-to-be-
deprecated functionality.  In particular, the standard flow is usually
something like this:

    static void run_test1(int fd, uint32_t engine)
    {
        igt_spin_t *spin;

        ctx = = gem_context_clone_with_engines(fd, 0);
        __igt_spin_new(fd, ctx, .engine = engine);

        /* do some testing with ctx */

        igt_spin_free(fd, spin);
        gem_destroy_context(fd, ctx);
    }

    igt_main
    {
        struct intel_execution_engine2 *e;

        /* Usual fixture code */

        __for_each_physical_engine(fd, e)
            run_test1(fd, e->flags);

        __for_each_physical_engine(fd, e)
            run_test2(fd, e->flags);
    }

Let's walk through what this does:

 1. __for_each_physical_engine calls intel_init_engine_list() which resets
    the set of engines on ctx0 to the full set of engines available as per
    the engine query.  On older kernels/hardware where we don't have the
    engines query, it leaves the set alone.

 2. intel_init_engine_list() also returns a set of engines for iteration
    and __for_each_physical_engine() sets up a for loop to walk the set.

 3. gem_context_clone_with_engines() creates a new context using
    I915_CONTEXT_CONTEXT_CLONE_ENGINES (not used by anything other than
    IGT) to ask that the newly created context has the same set of engines
    as ctx0.  Remember we changed that at the start of loop iteration!

 4. When the context is passed to __igt_spin_new(), it calls
    gem_context_lookup_engine which does a GETPARAM to introspet the set of
    engines on the context and figure out the engine class.

If you've been keeping track, this trivial and extremely common example
uses every single one of these soon-to-be-deprecated APIs even though the
test author may be completely obvious to it.  It also means that getting
rid of IGT's use of them is going to require some fairly deep surgery.

The approach proposed and partially implemented here is to add a new
wrapper struct intel_ctx_t which wraps a GEM context handle as well as the
full set of parameters used to create it, represented by intel_ctx_cfg_t.
We can then use the context anywhere we would regularly use a context, we
just have to do ctx->id.  If we want to clone it, we can do so by re-using
the create parameters by calling intel_ctx_create(fd, &old_ctx->cfg);

Along with the above rework (which got long, sorry) I've got a few other
patches in here which delete tests which exist expressly to test APIs that
are on the chopping block.

v2 (Jason Ekstrand):
 - Better documentation
 - Two more patches at the end to clean up query APIs even more

v3 (Jason Ekstrand):
 - Improved intel_ctx interface
 - More tests converted to intel_ctx_t
 - Misc. bug fixes

v4 (Jason Ekstrand):
 - Rebased
 - Add tests for new error conditions

v5 (Jason Ekstrand):
 - Apply review feedback from Zbigniew
 - Fix some issues caused by updates to the kernel series

v6 (Jason Ekstrand):
 - First 17 patches from the original have been merged
 - Apply review feedback from Ashutosh and Zbigniew
 - Fix some tests for the set-once rule for CONTEXT_PARAM_ENGINES

v7 (Jason Ekstrand):
 - Rebased on master
 - Apply review feedback from Ashutosh and Zbigniew

--Jason

Jason Ekstrand (79):
  lib/i915/gem_submission_measure: Take an optional intel_ctx_cfg_t
  tests/i915/gem_exec_fence: Move the engine data into
    inter_engine_context (v3)
  tests/i915/gem_exec_fence: Convert to intel_ctx_t (v2)
  tests/i915/gem_exec_schedule: Convert to intel_ctx_t (v2)
  tests/i915/perf_pmu: Convert to intel_ctx_t (v3)
  tests/i915/gem_exec_nop: Convert to intel_ctx_t
  tests/i915/gem_exec_reloc: Convert to intel_ctx_t (v3)
  tests/i915/gem_busy: Convert to intel_ctx_t (v3)
  tests/i915/gem_ctx_isolation: Convert to intel_ctx_t (v2)
  tests/i915/gem_exec_async: Convert to intel_ctx_t (v2)
  tests/i915/sysfs_clients: Convert to intel_ctx_t
  tests/i915/gem_exec_fair: Convert to intel_ctx_t
  tests/i915/gem_spin_batch: Convert to intel_ctx_t (v2)
  tests/i915/gem_exec_store: Convert to intel_ctx_t (v2)
  tests/amdgpu/amd_prime: Convert to intel_ctx_t
  tests/i915/i915_hangman: Convert to intel_ctx_t (v2)
  tests/i915/gem_ringfill: Convert to intel_ctx_t
  tests/prime_busy: Convert to intel_ctx_t
  tests/prime_vgem: Convert to intel_ctx_t (v2)
  tests/gem_exec_whisper: Convert to intel_ctx_t (v2)
  tests/i915/gem_ctx_exec: Stop cloning contexts in close_race
  tests/i915/gem_ctx_exec: Convert to intel_ctx_t
  tests/i915/gem_exec_suspend: Convert to intel_ctx_t (v2)
  tests/i915/gem_sync: Convert to intel_ctx_t (v2)
  tests/i915/gem_userptr_blits: Convert to intel_ctx_t
  tests/i915/gem_wait: Convert to intel_ctx_t (v2)
  tests/i915/gem_request_retire: Convert to intel_ctx_t
  tests/i915/gem_ctx_shared: Convert to intel_ctx_t (v2)
  tests/i915/gem_ctx_shared: Stop cloning contexts
  tests/i915/gem_create: Convert to intel_ctx_t
  tests/i915/gem_ctx_switch: Convert to intel_ctx_t
  tests/i915/gem_exec_parallel: Convert to intel_ctx_t (v2)
  tests/i915/gem_exec_latency: Convert to intel_ctx_t (v3)
  tests/i915/gem_watchdog: Convert to intel_ctx_t (v2)
  tests/i915/gem_shrink: Convert to intel_ctx_t (v4)
  tests/i915/gem_exec_params: Convert to intel_ctx_t
  tests/i915/gem_exec_gttfill: Convert to intel_ctx_t (v2)
  tests/i915/gem_exec_capture: Convert to intel_ctx_t (v2)
  tests/i915/gem_exec_create: Convert to intel_ctx_t
  tests/i915/gem_exec_await: Convert to intel_ctx_t (v2)
  tests/i915/gem_ctx_persistence: Drop the clone subtest
  tests/i915/gem_ctx_persistence: Drop the engine replace subtests
  tests/i915/gem_ctx_persistence: Convert to intel_ctx_t
  tests/i915/module_load: Convert to intel_ctx_t
  tests/i915/pm_rc6_residency: Convert to intel_ctx_t
  tests/i915/gem_cs_tlb: Convert to intel_ctx_t
  tests/core_hotplug: Convert to intel_ctx_t
  tests/i915/gem_exec_balancer: Stop cloning engines
  tests/i915/gem_exec_balancer: Don't reset engines on a context
  tests/i915/gem_exec_balancer: Stop munging ctx0 engines
  tests/i915/gem_exec_balancer: Drop bonded tests
  lib/intel_ctx: Add load balancing support (v2)
  tests/i915/gem_exec_balancer: Convert to intel_ctx_t
  tests/i915/gem_exec_endless: Stop munging ctx0 engines
  lib/i915/submission: Rework gem_test_all_engines to use intel_ctx_t
  lib/i915: Require a context config in gem_submission_measure
  tests/i915/gem_ctx_engines: Rework execute-one*
  tests/i915/gem_ctx_engines: Use better engine iteration
  tests/i915/gem_ctx_engines: Drop the idempotent subtest
  tests/i915/gem_ctx_create: Convert benchmarks to intel_ctx_t
  tests/i915/gem_vm_create: Delete destroy racing tests
  tests/i915/gem_vm_create: Use intel_ctx_t in the execbuf test
  tests/i915/sysfs: Convert to intel_ctx_t
  tests/i915/gem_workarounds: Convert to intel_ctx_t
  lib/i915/gem_context: Delete all the context clone/copy stuff
  tests/i915/gem_ctx_engines: Delete the libapi subtest
  lib/igt_dummyload: Stop supporting ALL_ENGINES without an intel_ctx_t
  lib/i915/gem_engine_topology: Delete the old physical engine iterators
  tests/i915/gem_mmap_gtt: Convert to intel_ctx_t
  igt/dummyload: Require an intel_ctx_t for POLL_RUN and !ALL_ENGINES
  lib/i915: Rework engine API availability checks (v2)
  lib/intel_bb: Remove intel_bb_assign_vm and tests (v2)
  tests/i915/gem_ctx_param: Stop setting VMs on old contexts
  tests/i915/gen9_exec_parse: Convert to intel_ctx_t
  tests/i915/gem_ctx_param: Add tests for recently removed params
  tests/i915/gem_ctx_param: Add a couple invalid PARAM_VM cases
  tests/i915/gem_ctx_engines: Fix the invalid subtest for the new rules
  tests/i915/gem_exec_balancer: Fix invalid-balancer for the set-once
    rule
  tests/i915/gem_exec_balancer: Add a test for combind balancing and
    bonding (v2)

 lib/i915/gem_context.c                | 199 +-----
 lib/i915/gem_context.h                |  18 +-
 lib/i915/gem_engine_topology.c        | 149 +----
 lib/i915/gem_engine_topology.h        |  20 -
 lib/i915/gem_submission.c             |  40 +-
 lib/i915/gem_submission.h             |   7 +-
 lib/igt_dummyload.c                   |  41 +-
 lib/intel_batchbuffer.c               |  65 --
 lib/intel_batchbuffer.h               |   4 -
 lib/intel_ctx.c                       |  63 +-
 lib/intel_ctx.h                       |   4 +
 tests/amdgpu/amd_prime.c              |  10 +-
 tests/core_hotunplug.c                |   6 +-
 tests/i915/api_intel_bb.c             | 104 ---
 tests/i915/gem_busy.c                 |  80 ++-
 tests/i915/gem_create.c               |  14 +-
 tests/i915/gem_cs_tlb.c               |  10 +-
 tests/i915/gem_ctx_create.c           |  76 ++-
 tests/i915/gem_ctx_engines.c          | 352 +++-------
 tests/i915/gem_ctx_exec.c             |  60 +-
 tests/i915/gem_ctx_isolation.c        | 127 ++--
 tests/i915/gem_ctx_param.c            |  75 ++-
 tests/i915/gem_ctx_persistence.c      | 457 ++++---------
 tests/i915/gem_ctx_shared.c           | 380 +++++++----
 tests/i915/gem_ctx_switch.c           | 115 ++--
 tests/i915/gem_eio.c                  |   2 +-
 tests/i915/gem_exec_async.c           |  32 +-
 tests/i915/gem_exec_await.c           |  29 +-
 tests/i915/gem_exec_balancer.c        | 907 ++++++++-----------------
 tests/i915/gem_exec_capture.c         |  31 +-
 tests/i915/gem_exec_create.c          |   9 +-
 tests/i915/gem_exec_endless.c         |   2 +-
 tests/i915/gem_exec_fair.c            | 112 ++--
 tests/i915/gem_exec_fence.c           | 306 +++++----
 tests/i915/gem_exec_gttfill.c         |  16 +-
 tests/i915/gem_exec_latency.c         | 122 ++--
 tests/i915/gem_exec_nop.c             | 156 +++--
 tests/i915/gem_exec_parallel.c        |  29 +-
 tests/i915/gem_exec_params.c          |   4 +-
 tests/i915/gem_exec_reloc.c           |  98 +--
 tests/i915/gem_exec_schedule.c        | 913 ++++++++++++++------------
 tests/i915/gem_exec_store.c           |  36 +-
 tests/i915/gem_exec_suspend.c         |  53 +-
 tests/i915/gem_exec_whisper.c         |  88 ++-
 tests/i915/gem_mmap_gtt.c             |  18 +-
 tests/i915/gem_request_retire.c       |  17 +-
 tests/i915/gem_ringfill.c             |  48 +-
 tests/i915/gem_shrink.c               |  18 +-
 tests/i915/gem_spin_batch.c           |  81 ++-
 tests/i915/gem_sync.c                 | 158 +++--
 tests/i915/gem_userptr_blits.c        |  25 +-
 tests/i915/gem_vm_create.c            | 125 +---
 tests/i915/gem_wait.c                 |  20 +-
 tests/i915/gem_watchdog.c             | 169 ++---
 tests/i915/gem_workarounds.c          |  13 +-
 tests/i915/gen9_exec_parse.c          | 106 +--
 tests/i915/i915_hangman.c             |  37 +-
 tests/i915/i915_module_load.c         |   7 +-
 tests/i915/i915_pm_rc6_residency.c    |   7 +-
 tests/i915/i915_pm_rpm.c              |   2 +-
 tests/i915/i915_query.c               |  17 +-
 tests/i915/perf_pmu.c                 | 243 ++++---
 tests/i915/sysfs_clients.c            |  87 +--
 tests/i915/sysfs_heartbeat_interval.c |  40 +-
 tests/i915/sysfs_preempt_timeout.c    |  39 +-
 tests/i915/sysfs_timeslice_duration.c |  51 +-
 tests/prime_busy.c                    |  19 +-
 tests/prime_vgem.c                    |  35 +-
 68 files changed, 3028 insertions(+), 3775 deletions(-)

-- 
2.31.1



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