[embedding] non-blocking cpu-gpu copy (#1647)

colossalai/nn/parallel/layers/cache_embedding/cache_mgr.py

@@ -38,6 +38,7 @@ class CachedParamMgr(torch.nn.Module):
         buffer_size: int = 0,
         pin_weight: bool = False,
         evict_strategy: EvictionStrategy = EvictionStrategy.DATASET,
+        async_copy: bool = False,
     ) -> None:
         super(CachedParamMgr, self).__init__()
         self.buffer_size = buffer_size
@@ -58,6 +59,11 @@ class CachedParamMgr(torch.nn.Module):
 
         self._evict_strategy = evict_strategy
 
+        self._async_copy = async_copy
+
+        if self._async_copy:
+            print('use async copy')
+
         if self._evict_strategy == EvictionStrategy.LFU:
             # cache_row_idx -> frequency, freq of the cache rows.
             # classic lfu cache. evict the minimal freq value row in cuda cache.
@@ -312,6 +318,18 @@ class CachedParamMgr(torch.nn.Module):
             cpu_row_idxs (torch.Tensor): the rows to be placed on CUDA
         """
         evict_num = cpu_row_idxs.numel() - self.cuda_available_row_num
+
+        cpu_row_idxs_copy = cpu_row_idxs.cpu()
+
+        # move evict in rows to gpu
+        if self._async_copy:
+            if self.buffer_size == 0:
+                rows_cpu = self.weight.view(self.num_embeddings, -1).index_select(0, cpu_row_idxs_copy).pin_memory()
+                evict_in_rows_gpu = torch.empty_like(rows_cpu, device=torch.cuda.current_device())
+                evict_in_rows_gpu.copy_(rows_cpu, non_blocking=True)
+            else:
+                raise NotImplemented
+
         if evict_num > 0:
             with Timer() as timer:
                 mask_cpu_row_idx = torch.isin(self.cached_idx_map, self.evict_backlist)
@@ -323,12 +341,24 @@ class CachedParamMgr(torch.nn.Module):
                     backup_idxs = self.cached_idx_map[mask_cpu_row_idx].clone()
                     self.cached_idx_map.index_fill_(0, invalid_idxs, -2)
                     evict_gpu_row_idxs = self._find_evict_gpu_idxs(evict_num)
+
+                    # move evict out rows to cpu
+                    if self._async_copy:
+                        evict_out_rows_gpu = self.cuda_cached_weight.view(self.cuda_row_num,
+                                                                          -1).index_select(0, evict_gpu_row_idxs)
+                        evict_out_rows_cpu = torch.empty_like(evict_out_rows_gpu, device='cpu', pin_memory=True)
+                        evict_out_rows_cpu.copy_(evict_out_rows_gpu, non_blocking=True)
                     self.cached_idx_map.index_copy_(0, invalid_idxs, backup_idxs)
 
                 elif self._evict_strategy == EvictionStrategy.LFU:
                     backup_freqs = self.freq_cnter[invalid_idxs].clone()
                     self.freq_cnter.index_fill_(0, invalid_idxs, sys.maxsize)
                     evict_gpu_row_idxs = self._find_evict_gpu_idxs(evict_num)
+                    if self._async_copy:
+                        evict_out_rows_gpu = self.cuda_cached_weight.view(self.cuda_row_num,
+                                                                          -1).index_select(0, evict_gpu_row_idxs)
+                        evict_out_rows_cpu = torch.empty_like(evict_out_rows_gpu, device='cpu', pin_memory=True)
+                        evict_out_rows_cpu.copy_(evict_out_rows_gpu, non_blocking=True)
                     self.freq_cnter.index_copy_(0, invalid_idxs, backup_freqs)
 
                 evict_info = self.cached_idx_map[evict_gpu_row_idxs]
@@ -341,8 +371,13 @@ class CachedParamMgr(torch.nn.Module):
                                                             tgt=self.weight.view(self.num_embeddings, -1))
                 else:
                     # allocate tmp memory on CPU and copy rows on CUDA to CPU.
-                    rows = self.cuda_cached_weight.view(self.cuda_row_num, -1).index_select(0, evict_gpu_row_idxs).cpu()
-                    self.weight.view(self.num_embeddings, -1).index_copy_(0, evict_info.cpu(), rows)
+                    # TODO async gpu -> cpu
+                    if self._async_copy:
+                        pass
+                    else:
+                        evict_out_rows_cpu = self.cuda_cached_weight.view(self.cuda_row_num,
+                                                                          -1).index_select(0, evict_gpu_row_idxs).cpu()
+                    self.weight.view(self.num_embeddings, -1).index_copy_(0, evict_info.cpu(), evict_out_rows_cpu)
 
                 self.cached_idx_map.index_fill_(0, evict_gpu_row_idxs, -1)
                 self.inverted_cached_idx.index_fill_(0, evict_info, -1)
@@ -359,13 +394,20 @@ class CachedParamMgr(torch.nn.Module):
             # Here also allocate extra memory on CUDA. #cpu_row_idxs
             if self.buffer_size > 0:
                 self.limit_buff_index_copyer.index_copy(0,
-                                                        src_index=cpu_row_idxs.cpu(),
+                                                        src_index=cpu_row_idxs_copy,
                                                         tgt_index=slots,
                                                         src=self.weight.view(self.num_embeddings, -1),
                                                         tgt=self.cuda_cached_weight.view(self.cuda_row_num, -1))
             else:
-                rows = self.weight.view(self.num_embeddings, -1).index_select(0, cpu_row_idxs.cpu()).cuda()
-                self.cuda_cached_weight.view(self.cuda_row_num, -1).index_copy_(0, slots, rows)
+                # TODO async copy cpu -> gpu
+                if self._async_copy:
+                    pass
+                else:
+                    evict_in_rows_gpu = self.weight.view(self.num_embeddings,
+                                                         -1).index_select(0, cpu_row_idxs_copy).cuda()
+
+                self.cuda_cached_weight.view(self.cuda_row_num, -1).index_copy_(0, slots, evict_in_rows_gpu)
+
             slot_offsets = slots
             self.cached_idx_map[slots] = cpu_row_idxs
             self.inverted_cached_idx.index_copy_(0, cpu_row_idxs, slot_offsets)
@@ -453,4 +495,4 @@ class CachedParamMgr(torch.nn.Module):
         self._cuda_available_row_num -= 1
 
         self._cpu_to_cuda_numel += self.embedding_dim
-        self._cpu_to_cuda_elpase += timer.elapsed
+        self._cpu_to_cuda_elpase += timer.elapsed