diff --git a/lib/simd/l1p.h b/lib/simd/l1p.h
new file mode 100644
index 00000000..8e43fdbd
--- /dev/null
+++ b/lib/simd/l1p.h
@@ -0,0 +1,37 @@
+#pragma once
+namespace Grid {
+// L1p optimisation 
+inline void bgq_l1p_optimisation(int mode)
+{
+#ifdef QPX
+#undef L1P_CFG_PF_USR
+#define L1P_CFG_PF_USR  (0x3fde8000108ll)   /*  (64 bit reg, 23 bits wide, user/unpriv) */
+
+  uint64_t cfg_pf_usr;
+  if ( mode ) { 
+    cfg_pf_usr =
+        L1P_CFG_PF_USR_ifetch_depth(0)       
+      | L1P_CFG_PF_USR_ifetch_max_footprint(1)   
+      | L1P_CFG_PF_USR_pf_stream_est_on_dcbt 
+      | L1P_CFG_PF_USR_pf_stream_establish_enable
+      | L1P_CFG_PF_USR_pf_stream_optimistic
+      | L1P_CFG_PF_USR_pf_adaptive_throttle(0xF) ;
+    //    if ( sizeof(Float) == sizeof(double) ) {
+      cfg_pf_usr |=  L1P_CFG_PF_USR_dfetch_depth(2)| L1P_CFG_PF_USR_dfetch_max_footprint(3)   ;
+      //    } else {
+      //      cfg_pf_usr |=  L1P_CFG_PF_USR_dfetch_depth(1)| L1P_CFG_PF_USR_dfetch_max_footprint(2)   ;
+      //    }
+  } else { 
+    cfg_pf_usr = L1P_CFG_PF_USR_dfetch_depth(1)
+      | L1P_CFG_PF_USR_dfetch_max_footprint(2)   
+      | L1P_CFG_PF_USR_ifetch_depth(0)       
+      | L1P_CFG_PF_USR_ifetch_max_footprint(1)   
+      | L1P_CFG_PF_USR_pf_stream_est_on_dcbt 
+      | L1P_CFG_PF_USR_pf_stream_establish_enable
+      | L1P_CFG_PF_USR_pf_stream_optimistic
+      | L1P_CFG_PF_USR_pf_stream_prefetch_enable;
+  }
+  *((uint64_t *)L1P_CFG_PF_USR) = cfg_pf_usr;
+#endif
+}
+}