Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
> During request construction, after pinning the context we know whether
> or not we have to emit a context switch. So move this common operation
> from every caller into i915_gem_request_alloc() itself.
>
> v2: Always submit the request if we emitted some commands during request
> construction, as typically it also involves changes in global state.
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 2 +-
> drivers/gpu/drm/i915/i915_gem_context.c | 7 +------
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 8 --------
> drivers/gpu/drm/i915/i915_gem_request.c | 18 +++++++++++++-----
> drivers/gpu/drm/i915/i915_perf.c | 3 +--
> drivers/gpu/drm/i915/intel_ringbuffer.c | 4 ++++
> drivers/gpu/drm/i915/selftests/huge_pages.c | 4 ----
> drivers/gpu/drm/i915/selftests/i915_gem_context.c | 4 ----
> drivers/gpu/drm/i915/selftests/i915_gem_request.c | 10 ----------
> drivers/gpu/drm/i915/selftests/intel_hangcheck.c | 4 ----
> 10 files changed, 20 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index a7979b74ce21..d885cf0d2943 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -5043,7 +5043,7 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
> goto out_ctx;
> }
>
> - err = i915_switch_context(rq);
> + err = 0;
> if (engine->init_context)
> err = engine->init_context(rq);
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 2db040695035..c1efbaf02bf2 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -842,8 +842,7 @@ int i915_switch_context(struct drm_i915_gem_request *req)
> struct intel_engine_cs *engine = req->engine;
>
> lockdep_assert_held(&req->i915->drm.struct_mutex);
> - if (i915_modparams.enable_execlists)
> - return 0;
> + GEM_BUG_ON(i915_modparams.enable_execlists);
>
> if (!req->ctx->engine[engine->id].state) {
> struct i915_gem_context *to = req->ctx;
> @@ -899,7 +898,6 @@ int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv)
>
> for_each_engine(engine, dev_priv, id) {
> struct drm_i915_gem_request *req;
> - int ret;
>
> if (engine_has_idle_kernel_context(engine))
> continue;
> @@ -922,10 +920,7 @@ int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv)
> GFP_KERNEL);
> }
>
> - ret = i915_switch_context(req);
> i915_add_request(req);
> - if (ret)
> - return ret;
> }
>
> return 0;
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 435ed95df144..85c7e8afe26e 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -1115,10 +1115,6 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb,
> if (err)
> goto err_request;
>
> - err = i915_switch_context(rq);
> - if (err)
> - goto err_request;
> -
> err = eb->engine->emit_bb_start(rq,
> batch->node.start, PAGE_SIZE,
> cache->gen > 5 ? 0 : I915_DISPATCH_SECURE);
> @@ -1965,10 +1961,6 @@ static int eb_submit(struct i915_execbuffer *eb)
> if (err)
> return err;
>
> - err = i915_switch_context(eb->request);
> - if (err)
> - return err;
> -
> if (eb->args->flags & I915_EXEC_GEN7_SOL_RESET) {
> err = i915_reset_gen7_sol_offsets(eb->request);
> if (err)
> diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c
> index e0d6221022a8..445495f9893c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_request.c
> +++ b/drivers/gpu/drm/i915/i915_gem_request.c
> @@ -624,6 +624,10 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
> if (ret)
> goto err_unpin;
>
> + ret = intel_ring_wait_for_space(ring, MIN_SPACE_FOR_ADD_REQUEST);
> + if (ret)
> + goto err_unreserve;
> +
> /* Move the oldest request to the slab-cache (if not in use!) */
> req = list_first_entry_or_null(&engine->timeline->requests,
> typeof(*req), link);
> @@ -703,10 +707,6 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
> req->reserved_space = MIN_SPACE_FOR_ADD_REQUEST;
> GEM_BUG_ON(req->reserved_space < engine->emit_breadcrumb_sz);
>
> - ret = engine->request_alloc(req);
> - if (ret)
> - goto err_ctx;
> -
> /* Record the position of the start of the request so that
> * should we detect the updated seqno part-way through the
> * GPU processing the request, we never over-estimate the
> @@ -714,16 +714,24 @@ i915_gem_request_alloc(struct intel_engine_cs *engine,
> */
> req->head = req->ring->emit;
>
> + ret = engine->request_alloc(req);
> + if (ret)
> + goto err_ctx;
> +
Ok as we don't emit anything with request alloc you can switch the
order.
> /* Check that we didn't interrupt ourselves with a new request */
> GEM_BUG_ON(req->timeline->seqno != req->fence.seqno);
> return req;
>
> err_ctx:
> + if (req->ring->emit != req->head) {
> + __i915_add_request(req, false);
> + return ERR_PTR(ret);
..so why this check. What could emit and why the early return?
And also more in generally, we do drop some error return patchs
due to removing switch_context(). Is there a risk of ignoring
and not propagating some error code we did actually catch
at i915_switch_context()?
-Mika
> + }
> +
> /* Make sure we didn't add ourselves to external state before freeing */
> GEM_BUG_ON(!list_empty(&req->active_list));
> GEM_BUG_ON(!list_empty(&req->priotree.signalers_list));
> GEM_BUG_ON(!list_empty(&req->priotree.waiters_list));
> -
> kmem_cache_free(dev_priv->requests, req);
> err_unreserve:
> unreserve_engine(engine);
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 00be015e01df..d8952ff8e6b7 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -1726,10 +1726,9 @@ static int gen8_switch_to_updated_kernel_context(struct drm_i915_private *dev_pr
> GFP_KERNEL);
> }
>
> - ret = i915_switch_context(req);
> i915_add_request(req);
>
> - return ret;
> + return 0;
> }
>
> /*
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 12e734b29463..be98868115bf 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -1592,6 +1592,10 @@ static int ring_request_alloc(struct drm_i915_gem_request *request)
> if (ret)
> return ret;
>
> + ret = i915_switch_context(request);
> + if (ret)
> + return ret;
> +
> request->reserved_space -= LEGACY_REQUEST_SIZE;
> return 0;
> }
> diff --git a/drivers/gpu/drm/i915/selftests/huge_pages.c b/drivers/gpu/drm/i915/selftests/huge_pages.c
> index 01af540b6ef9..eb142bd4c9e1 100644
> --- a/drivers/gpu/drm/i915/selftests/huge_pages.c
> +++ b/drivers/gpu/drm/i915/selftests/huge_pages.c
> @@ -993,10 +993,6 @@ static int gpu_write(struct i915_vma *vma,
> if (err)
> goto err_request;
>
> - err = i915_switch_context(rq);
> - if (err)
> - goto err_request;
> -
> err = rq->engine->emit_bb_start(rq,
> batch->node.start, batch->node.size,
> flags);
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
> index def5052862ae..61fcfa2c4dfd 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
> @@ -162,10 +162,6 @@ static int gpu_fill(struct drm_i915_gem_object *obj,
> if (err)
> goto err_request;
>
> - err = i915_switch_context(rq);
> - if (err)
> - goto err_request;
> -
> flags = 0;
> if (INTEL_GEN(vm->i915) <= 5)
> flags |= I915_DISPATCH_SECURE;
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_request.c b/drivers/gpu/drm/i915/selftests/i915_gem_request.c
> index a999161e8db1..9a35ebd5c876 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_request.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_request.c
> @@ -463,10 +463,6 @@ empty_request(struct intel_engine_cs *engine,
> if (err)
> goto out_request;
>
> - err = i915_switch_context(request);
> - if (err)
> - goto out_request;
> -
> err = engine->emit_bb_start(request,
> batch->node.start,
> batch->node.size,
> @@ -678,9 +674,6 @@ static int live_all_engines(void *arg)
> err = engine->emit_flush(request[id], EMIT_INVALIDATE);
> GEM_BUG_ON(err);
>
> - err = i915_switch_context(request[id]);
> - GEM_BUG_ON(err);
> -
> err = engine->emit_bb_start(request[id],
> batch->node.start,
> batch->node.size,
> @@ -800,9 +793,6 @@ static int live_sequential_engines(void *arg)
> err = engine->emit_flush(request[id], EMIT_INVALIDATE);
> GEM_BUG_ON(err);
>
> - err = i915_switch_context(request[id]);
> - GEM_BUG_ON(err);
> -
> err = engine->emit_bb_start(request[id],
> batch->node.start,
> batch->node.size,
> diff --git a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> index 71ce06680d66..cafe39e2e0f7 100644
> --- a/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> +++ b/drivers/gpu/drm/i915/selftests/intel_hangcheck.c
> @@ -118,10 +118,6 @@ static int emit_recurse_batch(struct hang *h,
> if (err)
> goto unpin_hws;
>
> - err = i915_switch_context(rq);
> - if (err)
> - goto unpin_hws;
> -
> i915_vma_move_to_active(vma, rq, 0);
> if (!i915_gem_object_has_active_reference(vma->obj)) {
> i915_gem_object_get(vma->obj);
> --
> 2.15.0
>
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