Default to 4 threads (#243)

utils.h

@@ -14,11 +14,11 @@
 
 struct gpt_params {
     int32_t seed      = -1; // RNG seed
-    int32_t n_threads;
+    int32_t n_threads = std::min(4, (int32_t) std::thread::hardware_concurrency());
     int32_t n_predict = 128; // new tokens to predict
     int32_t repeat_last_n = 64;  // last n tokens to penalize
     int32_t n_ctx = 512; //context size
-    
+
     // sampling parameters
     int32_t top_k = 40;
     float   top_p = 0.95f;