add external margin (#713)

Add envvar for SM margin in GEMM
Signed-off-by: Rachit Garg <rachitg@nvidia.com>
Co-authored-by: Rachit Garg <rachitg@nvidia.com>

transformer_engine/pytorch/csrc/comm_gemm_overlap.h

@@ -18,6 +18,7 @@
 #include <torch/types.h>
 
 #include "common/util/logging.h"
+#include "common/util/system.h"
 #include "userbuffers/userbuffers.h"
 
 #define HALF_BYTES 2
@@ -112,6 +113,7 @@ struct UbufCommOverlap : torch::CustomClassHolder, UbufBase {
     cudaDeviceProp prop;
     cudaGetDeviceProperties(&prop, 0);
     _math_sms = (set_sm_margin) ? prop.multiProcessorCount - num_comm_sm : prop.multiProcessorCount;
+    _math_sms -= transformer_engine::getenv<int>("NVTE_EXT_MARGIN_SM", 0);
 
     output_tensor = torch::Tensor();
     auto counter_options = torch::TensorOptions().dtype(torch::kInt32).device(torch::kCUDA);
@@ -587,6 +589,7 @@ struct UbufP2PCommOverlap : torch::CustomClassHolder, UbufBase {
     cudaDeviceProp prop;
     cudaGetDeviceProperties(&prop, 0);
     _math_sms = (set_sm_margin) ? prop.multiProcessorCount - num_comm_sm : prop.multiProcessorCount;
+    _math_sms -= transformer_engine::getenv<int>("NVTE_EXT_MARGIN_SM", 0);
 
     _tp_size = tp_size;
     _aggregate2 = aggregate2;

transformer_engine/pytorch/csrc/ts_fp8_op.cpp

@@ -6,7 +6,9 @@
 
 #include <torch/script.h>
 #include "extensions.h"
-
+#include <cuda.h>
+#include <cuda_fp8.h>
+#include "common/util/system.h"
 
 namespace {
   transformer_engine::DType reverse_map_dtype(int64_t dtype) {
@@ -316,6 +318,13 @@ at::Tensor te_gemm_ts(at::Tensor A,
   bool accumulate_arg = static_cast<bool>(accumulate);
   bool use_split_accumulator_arg = static_cast<bool>(use_split_accumulator);
 
+  // Set an external SM Margin to all the GEMMs.
+  // This comes in handy when DP is overlapped with GEMMs
+  cudaDeviceProp prop;
+  cudaGetDeviceProperties(&prop, 0);
+  int num_math_sms = prop.multiProcessorCount \
+                     - transformer_engine::getenv<int>("NVTE_EXT_MARGIN_SM", 0);
+
   if (A_scale_inverse.numel())
     A_scale_inverse = A_scale_inverse[A_fp8_tensor];
 
@@ -342,7 +351,7 @@ at::Tensor te_gemm_ts(at::Tensor A,
           workspaceSize_arg,
           accumulate_arg,
           use_split_accumulator_arg,
-          0);
+          num_math_sms);
   return D;
 }