delete critical section in TH*Tensor_addmm (#16889)

Summary:
This was serializing all calls to `addmm` (and any op that used it, in my case `bmm`) in the entire process, and led to downright atrocious performance in the TorchScript threaded runtime. Removing this gives a 2x throughput boost for high-load machine translation inference.

The original justification for this is dubious: there are other `gemm` callsites in the codebase that are not protected by critical sections. And in caffe2 land we never had any issues with nonreentrant BLAS libraries
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16889

Differential Revision: D14008928

Pulled By: jamesr66a

fbshipit-source-id: 498e2133bd6564dba539a2d9751f4e61afbce608

diff --git a/aten/src/TH/generic/THTensorMath.cpp b/aten/src/TH/generic/THTensorMath.cpp
index 29904c9..16ff7d2 100644 (file)
--- a/aten/src/TH/generic/THTensorMath.cpp
+++ b/aten/src/TH/generic/THTensorMath.cpp
@@ -1041,7 +1041,6 @@ void THTensor_(addmm)(THTensor *r_, scalar_t beta, THTensor *t, scalar_t alpha,
   int64_t ldm1_ = (transpose_m1 == 'n' ? m1_->stride((transpose_r == 'n' ? 1 : 0)) : m1_->stride((transpose_r == 'n' ? 0 : 1)));
   int64_t ldm2_ = (transpose_m2 == 'n' ? m2_->stride((transpose_r == 'n' ? 1 : 0)) : m2_->stride((transpose_r == 'n' ? 0 : 1)));
 
-#pragma omp critical(blasgemm)
   /* do the operation */
   THBlas_(gemm)(transpose_m1,
                 transpose_m2,