feat(core): support output var no copy

GitOrigin-RevId: fd68a1735b

src/core/impl/graph/cg_impl.cpp

@@ -492,6 +492,36 @@ SmallVector<std::unique_ptr<AsyncExecutable>> ComputingGraphImpl::compile_multi_
 #endif
 }
 
+void ComputingGraphImpl::dest_var_optimize(VarNodeArray& dest_vars) {
+    using F = VarNode::Flag;
+    if (dest_vars[0]->owner_graph()->options().force_output_dynamic_alloc) {
+        for (auto&& i : dest_vars) {
+            if (!i->contain_flag(F::NO_SYS_MEM_ALLOC | F::NO_SYS_STATIC_MEM_ALLOC)) {
+                mgb_assert(
+                        !i->contain_flag(F::DISALLOW_RT_FORCE_DYNAMIC_MEM_ALLOC),
+                        "Can not force graph output dynamic alloc with "
+                        "DISALLOW_RT_FORCE_DYNAMIC_MEM_ALLOC flag, var: %s",
+                        i->cname());
+                i->add_flag(F::NO_SYS_STATIC_MEM_ALLOC);
+            }
+            i->add_flag(F::NO_MEM_RECLAIM);
+        }
+    }
+    if (dest_vars[0]->owner_graph()->options().force_output_write_to_user_memory) {
+        for (auto&& i : dest_vars) {
+            mgb_assert(
+                    !i->contain_flag(F::RT_FORCE_DYNAMIC_MEM_ALLOC),
+                    "var %s with force dynamic allocate should be set to write output "
+                    "to "
+                    "user memory",
+                    i->cname());
+            i->add_flag(
+                    F::NO_SYS_MEM_ALLOC | F::NO_SYS_STATIC_MEM_ALLOC |
+                    F::NO_MEM_RECLAIM);
+        }
+    }
+}
+
 ComputingGraphImpl::CompileState ComputingGraphImpl::compile_prepare(
         const OutputSpec& out_spec) {
     auto&& cmpnt = components();
@@ -620,21 +650,7 @@ ComputingGraphImpl::CompileState ComputingGraphImpl::compile_prepare(
         std::unordered_map<
                 CallbackCallerKey, CallbackCallerVal, CallbackCallerKey::Hash>
                 opr2vars;
-        using F = VarNode::Flag;
-        if (dest_vars[0]->owner_graph()->options().force_output_dynamic_alloc) {
-            for (auto&& i : dest_vars) {
-                if (!i->contain_flag(
-                            F::NO_SYS_MEM_ALLOC | F::NO_SYS_STATIC_MEM_ALLOC)) {
-                    mgb_assert(
-                            !i->contain_flag(F::DISALLOW_RT_FORCE_DYNAMIC_MEM_ALLOC),
-                            "Can not force graph output dynamic alloc with "
-                            "DISALLOW_RT_FORCE_DYNAMIC_MEM_ALLOC flag, var: %s",
-                            i->cname());
-                    i->add_flag(F::NO_SYS_STATIC_MEM_ALLOC);
-                }
-                i->add_flag(F::NO_MEM_RECLAIM);
-            }
-        }
+        dest_var_optimize(dest_vars);
         for (size_t i = 0; i < out_spec.size(); ++i) {
             auto&& cb = out_spec[i].second;
             if (cb) {

src/core/impl/graph/cg_impl.h

@@ -142,6 +142,9 @@ class ComputingGraphImpl final : public ComputingGraph {
     //! finalize the computing sequence for compiling
     std::unique_ptr<AsyncExecutable> compile_commit(CompileState state);
 
+    //! process the dest var optimization
+    void dest_var_optimize(VarNodeArray& dest_vars);
+
 public:
     class ComputingSequence;
 

src/core/impl/graph/var_node.cpp

@@ -582,7 +582,8 @@ VarNode& VarNode::add_flag(Flag flag) {
 void VarNode::modify_flag(Flag delta, Flag new_flag) {
     if (contain_flag(Flag::FLAG_FREEZED)) {
         mgb_assert(
-                (delta & (Flag::NO_MEM_RECLAIM | Flag::NO_SYS_STATIC_MEM_ALLOC |
+                (delta & (Flag::NO_SYS_MEM_ALLOC | Flag::NO_MEM_RECLAIM |
+                          Flag::NO_SYS_STATIC_MEM_ALLOC |
                           Flag::RT_FORCE_DYNAMIC_MEM_ALLOC)) == delta ||
                 (new_flag & Flag::MEMORY_NO_NEED));
 

src/core/include/megbrain/graph/cg.h

@@ -417,6 +417,12 @@ public:
          */
         bool force_output_dynamic_alloc = false;
 
+        /*!
+         * Force the output to be written to the user specified memory, which
+         * can optimize the copy of output data at one time
+         */
+        bool force_output_write_to_user_memory = false;
+
         //! whether to perform var sanity check on first run
         bool var_sanity_check_first_run = true;
 

src/gopt/test/no_memory_copy.cpp

@@ -0,0 +1,165 @@
+/**
+ * \file src/gopt/test/no_memory_copy.cpp
+ *
+ * Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ */
+
+#include <memory>
+#include "./network.h"
+#include "megbrain/comp_node_env.h"
+#include "megbrain/opr/basic_arith.h"
+#include "megbrain/test/helper.h"
+
+using namespace mgb;
+
+struct TestGraph {
+    CompNode m_cn;
+    HostTensorGenerator<> m_gen;
+    std::unique_ptr<Network> m_network;
+    SymbolVar m_out_var;
+    std::shared_ptr<HostTensorND> input_tensor;
+
+    TestGraph() {
+        m_cn = CompNode::load("cpu0");
+        m_network = std::make_unique<Network>(m_cn);
+    }
+
+    void create_graph() {
+        input_tensor = m_gen({1, 3, 32, 32}, m_cn);
+        auto input = opr::Host2DeviceCopy::make(*m_network->graph, input_tensor, m_cn)
+                             .rename("input");
+        auto f = m_network->add_conv(
+                input, 4, {3, 3}, dtype::Float32(), true, {2, 2}, {0, 0});
+        f = m_network->add_elemwise(
+                {f}, dtype::Float32(), opr::Elemwise::Param::Mode::EXP);
+        f = m_network->add_conv(f, 8, {3, 3}, dtype::Float32(), true, {1, 1}, {1, 1});
+        m_out_var = m_network->add_pooling(f, {2, 2}, {2, 2});
+    }
+
+    std::unique_ptr<cg::AsyncExecutable> compile_without_copy() {
+        return m_network->graph->compile({{m_out_var, nullptr}});
+    }
+
+    std::unique_ptr<cg::AsyncExecutable> compile_with_copy(HostTensorND& host) {
+        auto cb = [&host](const DeviceTensorND& dv) mutable { host.copy_from(dv); };
+        return m_network->graph->compile({{m_out_var, std::move(cb)}});
+    }
+};
+
+TEST(TestNoCopy, BasicInputNoCopy) {
+    auto test_graph = TestGraph();
+    test_graph.create_graph();
+    HostTensorND out, out_pre;
+    auto func = test_graph.compile_with_copy(out);
+    size_t times = 10;
+    for (size_t i = 0; i < times; i++) {
+        if (i % 2 == 0) {
+            auto input_tensor = test_graph.input_tensor;
+            auto layout = input_tensor->layout();
+            size_t length = layout.total_nr_elems();
+            auto storage = TensorStorage<HostTensorStorageTrait>(test_graph.m_cn);
+            storage.ensure_size(length * sizeof(float));
+            float* ptr = storage.ptr()->as<float>();
+            for (size_t d = 0; d < length; d++) {
+                ptr[d] = i;
+            }
+            input_tensor->reset(storage, layout);
+        }
+        func->execute();
+        func->wait();
+        if (i % 2 != 0) {
+            MGB_ASSERT_TENSOR_EQ(out, out_pre);
+        }
+        out_pre.copy_from(out).sync();
+    }
+}
+
+TEST(TestNoCopy, IONoCopyPtrEQ) {
+    auto test_graph = TestGraph();
+    auto compute_graph = test_graph.m_network->graph;
+    compute_graph->options().force_output_write_to_user_memory = true;
+    test_graph.create_graph();
+    auto func = test_graph.compile_without_copy();
+    auto&& outvar = func->get_output_vars()[0];
+    DeviceTensorND dv0(test_graph.m_cn, {1, 8, 7, 7});
+    DeviceTensorND dv1(test_graph.m_cn, {1, 8, 7, 7});
+    size_t times = 10;
+    for (size_t i = 0; i < times; i++) {
+        auto input_tensor = test_graph.input_tensor;
+        auto layout = input_tensor->layout();
+        size_t length = layout.total_nr_elems();
+        auto storage = TensorStorage<HostTensorStorageTrait>(test_graph.m_cn);
+        storage.ensure_size(length * sizeof(float));
+        float* ptr = storage.ptr()->as<float>();
+        for (size_t d = 0; d < length; d++) {
+            ptr[d] = i;
+        }
+        input_tensor->reset(storage, layout);
+        if (i % 2 == 0) {
+            outvar->init_mem_plan(&dv0);
+            outvar->reset_dev_tensor_from_tensor(dv0);
+        } else {
+            outvar->init_mem_plan(&dv1);
+            outvar->reset_dev_tensor_from_tensor(dv1);
+        }
+
+        func->execute();
+        func->wait();
+        auto out = func->get_output_vars()[0]->dev_tensor().ptr<float>();
+
+        if (i % 2 == 0) {
+            ASSERT_EQ(dv0.ptr<float>(), out);
+        } else {
+            ASSERT_EQ(dv1.ptr<float>(), out);
+        }
+    }
+}
+
+TEST(TestNoCopy, IONoCopyCorrect) {
+    auto test_graph = TestGraph();
+    auto compute_graph = test_graph.m_network->graph;
+    compute_graph->options().force_output_write_to_user_memory = true;
+    test_graph.create_graph();
+    HostTensorND truth;
+    auto func = test_graph.compile_without_copy();
+    //! because the output tensor not assign user memory, so it will wrong
+    ASSERT_THROW(func->execute(), MegBrainError);
+    auto&& outvar = func->get_output_vars()[0];
+    size_t times = 10;
+    for (size_t i = 0; i < times; i++) {
+        auto input_tensor = test_graph.input_tensor;
+        auto layout = input_tensor->layout();
+        size_t length = layout.total_nr_elems();
+        auto storage = TensorStorage<HostTensorStorageTrait>(test_graph.m_cn);
+        storage.ensure_size(length * sizeof(float));
+        float* ptr = storage.ptr()->as<float>();
+        for (size_t d = 0; d < length; d++) {
+            ptr[d] = i / 5 + 3;
+        }
+        input_tensor->reset(storage, layout);
+        DeviceTensorND dv(test_graph.m_cn, {1, 8, 7, 7});
+        outvar->init_mem_plan(&dv);
+        outvar->reset_dev_tensor_from_tensor(dv);
+
+        func->execute();
+        func->wait();
+        if (i % 5 == 0) {
+            truth.copy_from(func->get_output_vars()[0]->dev_tensor()).sync();
+            continue;
+        }
+        HostTensorND to_check;
+        to_check.copy_from(func->get_output_vars()[0]->dev_tensor()).sync();
+        MGB_ASSERT_TENSOR_EQ(to_check, truth);
+    }
+}
+
+TEST(TestNoCopy, InputNoCopyRecord) {}
+
+TEST(TestNoCopy, OutputNoCopyRecord) {}
+
+// vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}