Add flag on how host memory is allocated

Add a bool flag to record whether a host memory is allocated using malloc or
cudaMallocHost, and free correspondingly using this flag, instead of depending on Caffe::mode(), which is mutable during runtime.

include/caffe/syncedmem.hpp

@@ -13,20 +13,22 @@ namespace caffe {
 // The improvement in performance seems negligible in the single GPU case,
 // but might be more significant for parallel training. Most importantly,
 // it improved stability for large models on many GPUs.
-inline void CaffeMallocHost(void** ptr, size_t size) {
+inline void CaffeMallocHost(void** ptr, size_t size, bool* use_cuda) {
 #ifndef CPU_ONLY
   if (Caffe::mode() == Caffe::GPU) {
     CUDA_CHECK(cudaMallocHost(ptr, size));
+    *use_cuda = true;
     return;
   }
 #endif
   *ptr = malloc(size);
+  *use_cuda = false;
   CHECK(*ptr) << "host allocation of size " << size << " failed";
 }
 
-inline void CaffeFreeHost(void* ptr) {
+inline void CaffeFreeHost(void* ptr, bool use_cuda) {
 #ifndef CPU_ONLY
-  if (Caffe::mode() == Caffe::GPU) {
+  if (use_cuda) {
     CUDA_CHECK(cudaFreeHost(ptr));
     return;
   }
@@ -45,10 +47,12 @@ class SyncedMemory {
  public:
   SyncedMemory()
       : cpu_ptr_(NULL), gpu_ptr_(NULL), size_(0), head_(UNINITIALIZED),
-        own_cpu_data_(false), own_gpu_data_(false), gpu_device_(-1) {}
+        own_cpu_data_(false), cpu_malloc_use_cuda_(false), own_gpu_data_(false),
+        gpu_device_(-1) {}
   explicit SyncedMemory(size_t size)
       : cpu_ptr_(NULL), gpu_ptr_(NULL), size_(size), head_(UNINITIALIZED),
-        own_cpu_data_(false), own_gpu_data_(false), gpu_device_(-1) {}
+        own_cpu_data_(false), cpu_malloc_use_cuda_(false), own_gpu_data_(false),
+        gpu_device_(-1) {}
   ~SyncedMemory();
   const void* cpu_data();
   void set_cpu_data(void* data);
@@ -72,6 +76,7 @@ class SyncedMemory {
   size_t size_;
   SyncedHead head_;
   bool own_cpu_data_;
+  bool cpu_malloc_use_cuda_;
   bool own_gpu_data_;
   int gpu_device_;
 

src/caffe/syncedmem.cpp

@@ -8,7 +8,7 @@ namespace caffe {
 
 SyncedMemory::~SyncedMemory() {
   if (cpu_ptr_ && own_cpu_data_) {
-    CaffeFreeHost(cpu_ptr_);
+    CaffeFreeHost(cpu_ptr_, cpu_malloc_use_cuda_);
   }
 
 #ifndef CPU_ONLY
@@ -27,15 +27,15 @@ SyncedMemory::~SyncedMemory() {
 inline void SyncedMemory::to_cpu() {
   switch (head_) {
   case UNINITIALIZED:
-    CaffeMallocHost(&cpu_ptr_, size_);
+    CaffeMallocHost(&cpu_ptr_, size_, &cpu_malloc_use_cuda_);
     caffe_memset(size_, 0, cpu_ptr_);
     head_ = HEAD_AT_CPU;
     own_cpu_data_ = true;
     break;
   case HEAD_AT_GPU:
 #ifndef CPU_ONLY
     if (cpu_ptr_ == NULL) {
-      CaffeMallocHost(&cpu_ptr_, size_);
+      CaffeMallocHost(&cpu_ptr_, size_, &cpu_malloc_use_cuda_);
       own_cpu_data_ = true;
     }
     caffe_gpu_memcpy(size_, gpu_ptr_, cpu_ptr_);
@@ -86,7 +86,7 @@ const void* SyncedMemory::cpu_data() {
 void SyncedMemory::set_cpu_data(void* data) {
   CHECK(data);
   if (own_cpu_data_) {
-    CaffeFreeHost(cpu_ptr_);
+    CaffeFreeHost(cpu_ptr_, cpu_malloc_use_cuda_);
   }
   cpu_ptr_ = data;
   head_ = HEAD_AT_CPU;