From 6b67d25d9f6f242b566eac8b0ed0169fd65a39c1 Mon Sep 17 00:00:00 2001
From: laurent <laurent.mazare@gmail.com>
Date: Fri, 30 Jun 2023 18:46:32 +0100
Subject: [PATCH] Do not use rayon for a single thread.

---
 candle-core/src/cpu_backend.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/candle-core/src/cpu_backend.rs b/candle-core/src/cpu_backend.rs
index b9300534..5af7c019 100644
--- a/candle-core/src/cpu_backend.rs
+++ b/candle-core/src/cpu_backend.rs
@@ -249,6 +249,12 @@ impl Map2 for MatMul {
             let lhs_p = &lhs[step * a_skip..];
             let rhs_p = &rhs[step * b_skip..];
             let dst_p = &mut dst[step * c_skip..];
+            let num_threads = crate::utils::get_num_threads();
+            let parallelism = if num_threads > 1 {
+                Parallelism::Rayon(crate::utils::get_num_threads())
+            } else {
+                Parallelism::None
+            };
             unsafe {
                 gemm(
                     /* m: usize = */ m,
@@ -269,7 +275,7 @@ impl Map2 for MatMul {
                     /* conj_dst: bool = */ false,
                     /* conj_lhs: bool = */ false,
                     /* conj_rhs: bool = */ false,
-                    Parallelism::Rayon(crate::utils::get_num_threads()),
+                    parallelism,
                 )
             }
         }