The CS pre-parser can pre-fetch commands across memory sync points and starting from gen12 it is able to pre-fetch across BB_START and BB_END boundaries as well, so when we emit gpu relocs the pre-parser might fetch the target location of the reloc before the memory write lands.
The parser can't pre-fetch across the ctx switch, so we use a separate context to guarantee that the memory is syncronized before the parser can get to it. Suggested-by: Chris Wilson <[email protected]> Signed-off-by: Daniele Ceraolo Spurio <[email protected]> Cc: Chris Wilson <[email protected]> --- .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 27 ++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index b5f6937369ea..d27201c654e9 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -252,6 +252,7 @@ struct i915_execbuffer { bool has_fence : 1; bool needs_unfenced : 1; + struct intel_context *ce; struct i915_request *rq; u32 *rq_cmd; unsigned int rq_size; @@ -903,6 +904,7 @@ static void reloc_cache_init(struct reloc_cache *cache, cache->has_fence = cache->gen < 4; cache->needs_unfenced = INTEL_INFO(i915)->unfenced_needs_alignment; cache->node.allocated = false; + cache->ce = NULL; cache->rq = NULL; cache->rq_size = 0; } @@ -943,6 +945,7 @@ static void reloc_gpu_flush(struct reloc_cache *cache) static void reloc_cache_reset(struct reloc_cache *cache) { void *vaddr; + struct intel_context *ce; if (cache->rq) reloc_gpu_flush(cache); @@ -973,6 +976,10 @@ static void reloc_cache_reset(struct reloc_cache *cache) } } + ce = fetch_and_zero(&cache->ce); + if (ce) + intel_context_put(ce); + cache->vaddr = 0; cache->page = -1; } @@ -1168,7 +1175,7 @@ static int __reloc_gpu_alloc(struct i915_execbuffer *eb, if (err) goto err_unmap; - rq = i915_request_create(eb->context); + rq = intel_context_create_request(cache->ce); if (IS_ERR(rq)) { err = PTR_ERR(rq); goto err_unpin; @@ -1239,6 +1246,24 @@ static u32 *reloc_gpu(struct i915_execbuffer *eb, if (!intel_engine_can_store_dword(eb->engine)) return ERR_PTR(-ENODEV); + /* + * The CS pre-parser can pre-fetch commands across memory sync + * points and starting gen12 it is able to pre-fetch across + * BB_START and BB_END boundaries (within the same context). We + * use a separate context to guarantee that the reloc writes + * land before the parser gets to the target memory location. + */ + if (!cache->ce) { + struct intel_context *ce; + + ce = intel_context_create(eb->context->gem_context, + eb->engine); + if (IS_ERR(ce)) + return ERR_CAST(ce); + + cache->ce = ce; /* released in reloc_cache_reset */ + } + err = __reloc_gpu_alloc(eb, vma, len); if (unlikely(err)) return ERR_PTR(err); -- 2.23.0 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
