diff --git a/benchmarks/Benchmark_ITT.cc b/benchmarks/Benchmark_ITT.cc
index 4f16b1de..9bf7d0a5 100644
--- a/benchmarks/Benchmark_ITT.cc
+++ b/benchmarks/Benchmark_ITT.cc
@@ -218,7 +218,7 @@ public:
     std::cout<<GridLogMessage << "----------------------------------------------------------"<<std::endl;
   
   uint64_t lmax=48;
-#define NLOOP (10*lmax*lmax*lmax*lmax/lat/lat/lat/lat)
+#define NLOOP (50*lmax*lmax*lmax*lmax/lat/lat/lat/lat)
 
     GridSerialRNG          sRNG;      sRNG.SeedFixedIntegers(std::vector<int>({45,12,81,9}));
     for(int lat=8;lat<=lmax;lat+=4){
@@ -368,7 +368,7 @@ public:
       const int num_cases = 4;
 #endif
       controls Cases [] = {
-#if defined(AVX512) 
+#ifdef AVX512
 	{ QCD::WilsonKernelsStatic::OptInlineAsm , QCD::WilsonKernelsStatic::CommsAndCompute  ,CartesianCommunicator::CommunicatorPolicySequential  },
 	{ QCD::WilsonKernelsStatic::OptInlineAsm , QCD::WilsonKernelsStatic::CommsThenCompute ,CartesianCommunicator::CommunicatorPolicySequential  },
 #endif
@@ -380,6 +380,10 @@ public:
 
       for(int c=0;c<num_cases;c++) {
 
+	QCD::WilsonKernelsStatic::Comms = Cases[c].CommsOverlap;
+	QCD::WilsonKernelsStatic::Opt   = Cases[c].Opt;
+	CartesianCommunicator::SetCommunicatorPolicy(Cases[c].CommsAsynch);
+
 	std::cout<<GridLogMessage << "=================================================================================="<<std::endl;
 	if ( WilsonKernelsStatic::Opt == WilsonKernelsStatic::OptGeneric   ) std::cout << GridLogMessage<< "* Using GENERIC Nc WilsonKernels" <<std::endl;
 	if ( WilsonKernelsStatic::Opt == WilsonKernelsStatic::OptHandUnroll) std::cout << GridLogMessage<< "* Using Nc=3       WilsonKernels" <<std::endl;
@@ -390,10 +394,6 @@ public:
 	if ( sizeof(Real)==8 )   std::cout << GridLogMessage<< "* DOUBLE precision "<<std::endl;
 	std::cout<<GridLogMessage << "=================================================================================="<<std::endl;
 
-
-	QCD::WilsonKernelsStatic::Comms = Cases[c].CommsOverlap;
-	QCD::WilsonKernelsStatic::Opt   = Cases[c].Opt;
-	CartesianCommunicator::SetCommunicatorPolicy(Cases[c].CommsAsynch);
 	int nwarm = 10;
 	double t0=usecond();
 	FGrid->Barrier();
diff --git a/lib/communicator/Communicator_base.cc b/lib/communicator/Communicator_base.cc
index 6767495f..3ce3a774 100644
--- a/lib/communicator/Communicator_base.cc
+++ b/lib/communicator/Communicator_base.cc
@@ -41,6 +41,7 @@ uint64_t            CartesianCommunicator::MAX_MPI_SHM_BYTES   = 128*1024*1024;
 CartesianCommunicator::CommunicatorPolicy_t  
 CartesianCommunicator::CommunicatorPolicy= CartesianCommunicator::CommunicatorPolicyConcurrent;
 int CartesianCommunicator::nCommThreads = -1;
+int CartesianCommunicator::Hugepages = 0;
 
 /////////////////////////////////
 // Alloc, free shmem region
@@ -134,7 +135,10 @@ void *CartesianCommunicator::ShmBufferTranslate(int rank,void * local_p) {
 }
 void CartesianCommunicator::ShmInitGeneric(void){
 #if 1
-  ShmCommBuf =(void *) mmap(NULL, MAX_MPI_SHM_BYTES, PROT_READ | PROT_WRITE,  MAP_HUGETLB| MAP_SHARED | MAP_ANONYMOUS, -1, 0); 
+
+  int mmap_flag = MAP_SHARED | MAP_ANONYMOUS;
+  if ( Hugepages ) mmap_flag |= MAP_HUGETLB;
+  ShmCommBuf =(void *) mmap(NULL, MAX_MPI_SHM_BYTES, PROT_READ | PROT_WRITE, mmap_flag, -1, 0); 
   if (ShmCommBuf == (void *)MAP_FAILED) exit(EXIT_FAILURE);  
   std::cout << "ShmCommBuf "<<ShmCommBuf<<std::endl;
 #else 
diff --git a/lib/communicator/Communicator_base.h b/lib/communicator/Communicator_base.h
index 84dbedb4..ac7d94f3 100644
--- a/lib/communicator/Communicator_base.h
+++ b/lib/communicator/Communicator_base.h
@@ -50,13 +50,24 @@ namespace Grid {
 class CartesianCommunicator {
   public:    
 
-  // 65536 ranks per node adequate for now
+
+  ////////////////////////////////////////////
+  // Isend/Irecv/Wait, or Sendrecv blocking
+  ////////////////////////////////////////////
+  enum CommunicatorPolicy_t { CommunicatorPolicyConcurrent, CommunicatorPolicySequential };
+  static CommunicatorPolicy_t CommunicatorPolicy;
+  static void SetCommunicatorPolicy(CommunicatorPolicy_t policy ) { CommunicatorPolicy = policy; }
+
+  ///////////////////////////////////////////
+  // Up to 65536 ranks per node adequate for now
   // 128MB shared memory for comms enought for 48^4 local vol comms
   // Give external control (command line override?) of this
-
+  ///////////////////////////////////////////
   static const int MAXLOG2RANKSPERNODE = 16;            
   static uint64_t  MAX_MPI_SHM_BYTES;
   static int       nCommThreads;
+  // use explicit huge pages
+  static int       Hugepages;
 
   // Communicator should know nothing of the physics grid, only processor grid.
   int              _Nprocessors;     // How many in all
@@ -122,10 +133,6 @@ class CartesianCommunicator {
   /////////////////////////////////
   static void * ShmCommBuf;
 
-  // Isend/Irecv/Wait, or Sendrecv blocking
-  enum CommunicatorPolicy_t { CommunicatorPolicyConcurrent, CommunicatorPolicySequential };
-  static CommunicatorPolicy_t CommunicatorPolicy;
-  static void SetCommunicatorPolicy(CommunicatorPolicy_t policy ) { CommunicatorPolicy = policy; }
   
   size_t heap_top;
   size_t heap_bytes;
diff --git a/lib/communicator/Communicator_mpi3.cc b/lib/communicator/Communicator_mpi3.cc
index e6e33d33..4f769971 100644
--- a/lib/communicator/Communicator_mpi3.cc
+++ b/lib/communicator/Communicator_mpi3.cc
@@ -41,8 +41,13 @@ Author: Peter Boyle <paboyle@ph.ed.ac.uk>
 #ifdef HAVE_NUMAIF_H
 #include <numaif.h>
 #endif
+
+// Make up for linex deficiencies
 #ifndef SHM_HUGETLB
-#define SHM_HUGETLB 04000
+#define SHM_HUGETLB 0x0
+#endif
+#ifndef MAP_HUGETLB
+#define MAP_HUGETLB 0x0
 #endif
 
 namespace Grid {
@@ -213,8 +218,11 @@ void CartesianCommunicator::Init(int *argc, char ***argv) {
       int fd=shm_open(shm_name,O_RDWR|O_CREAT,0666);
       if ( fd < 0 ) {	perror("failed shm_open");	assert(0);      }
       ftruncate(fd, size);
+      
+      int mmap_flag = MAP_SHARED;
+      if (Hugepages) mmap_flag |= MAP_HUGETLB;
+      void * ptr =  mmap(NULL,size, PROT_READ | PROT_WRITE, mmap_flag, fd, 0);
 
-      void * ptr =  mmap(NULL,size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
       if ( ptr == MAP_FAILED ) {       perror("failed mmap");      assert(0);    }
       assert(((uint64_t)ptr&0x3F)==0);
 
@@ -628,8 +636,9 @@ double CartesianCommunicator::StencilSendToRecvFrom( void *xmit,
 						     int bytes,int dir)
 {
   std::vector<CommsRequest_t> list;
-  StencilSendToRecvFromBegin(list,xmit,dest,recv,from,bytes,dir);
+  double offbytes = StencilSendToRecvFromBegin(list,xmit,dest,recv,from,bytes,dir);
   StencilSendToRecvFromComplete(list,dir);
+  return offbytes;
 }
 
 double CartesianCommunicator::StencilSendToRecvFromBegin(std::vector<CommsRequest_t> &list,
@@ -671,7 +680,7 @@ double CartesianCommunicator::StencilSendToRecvFromBegin(std::vector<CommsReques
   }
 
   if ( CommunicatorPolicy == CommunicatorPolicySequential ) { 
-    this->StencilSendToRecvFromComplete(list);
+    this->StencilSendToRecvFromComplete(list,dir);
   }
 
   return off_node_bytes;
diff --git a/lib/qcd/action/fermion/WilsonFermion5D.cc b/lib/qcd/action/fermion/WilsonFermion5D.cc
index 0b6c9e3d..404ecce0 100644
--- a/lib/qcd/action/fermion/WilsonFermion5D.cc
+++ b/lib/qcd/action/fermion/WilsonFermion5D.cc
@@ -135,10 +135,11 @@ WilsonFermion5D<Impl>::WilsonFermion5D(GaugeField &_Umu,
 template<class Impl>
 void WilsonFermion5D<Impl>::Report(void)
 {
-    std::vector<int> latt = GridDefaultLatt();          
-    RealD volume = Ls;  for(int mu=0;mu<Nd;mu++) volume=volume*latt[mu];
-    RealD NP = _FourDimGrid->_Nprocessors;
-    RealD NN = _FourDimGrid->NodeCount();
+  RealD NP     = _FourDimGrid->_Nprocessors;
+  RealD NN     = _FourDimGrid->NodeCount();
+  RealD volume = Ls;  
+  std::vector<int> latt = _FourDimGrid->GlobalDimensions();
+  for(int mu=0;mu<Nd;mu++) volume=volume*latt[mu];
 
   if ( DhopCalls > 0 ) {
     std::cout << GridLogMessage << "#### Dhop calls report " << std::endl;
@@ -390,17 +391,18 @@ void WilsonFermion5D<Impl>::DhopInternalOverlappedComms(StencilImpl & st, Lebesg
   st.CommsMergeSHM(compressor);// Could do this inside parallel region overlapped with comms
   DhopFaceTime+=usecond();
 
-  // Rely on async comms; start comms before merge of local data
   double ctime=0;
   double ptime=0;
-  //  DhopComputeTime-=usecond();
-  //  DhopCommTime-=usecond();
+
+  //////////////////////////////////////////////////////////////////////////////////////////////////////
+  // Ugly explicit thread mapping introduced for OPA reasons.
+  //////////////////////////////////////////////////////////////////////////////////////////////////////
 #pragma omp parallel reduction(max:ctime) reduction(max:ptime)
   { 
     int tid = omp_get_thread_num();
     int nthreads = omp_get_num_threads();
     int ncomms = CartesianCommunicator::nCommThreads;
-    if (ncomms == -1) ncomms = st.Packets.size(); 
+    if (ncomms == -1) ncomms = 1;
     assert(nthreads > ncomms);
     if (tid >= ncomms) {
       double start = usecond();
diff --git a/lib/stencil/Stencil.h b/lib/stencil/Stencil.h
index d1d7a7e0..cca67587 100644
--- a/lib/stencil/Stencil.h
+++ b/lib/stencil/Stencil.h
@@ -252,10 +252,15 @@ class CartesianStencil { // Stencil runs along coordinate axes only; NO diagonal
   //////////////////////////////////////////
   void CommunicateThreaded()
   {
+#ifdef GRID_OMP
     // must be called in parallel region
     int mythread = omp_get_thread_num();
     int nthreads = CartesianCommunicator::nCommThreads;
-    if (nthreads == -1) nthreads = Packets.size();
+#else
+    int mythread = 0;
+    int nthreads = 1;
+#endif
+    if (nthreads == -1) nthreads = 1;
     if (mythread < nthreads) {
       for (int i = mythread; i < Packets.size(); i += nthreads) {
 	double start = usecond();
diff --git a/lib/util/Init.cc b/lib/util/Init.cc
index 39a726cf..3fd8b4cd 100644
--- a/lib/util/Init.cc
+++ b/lib/util/Init.cc
@@ -222,6 +222,11 @@ void Grid_init(int *argc,char ***argv)
     CartesianCommunicator::MAX_MPI_SHM_BYTES = MB*1024*1024;
   }
 
+  if( GridCmdOptionExists(*argv,*argv+*argc,"--shm-hugepages") ){
+    CartesianCommunicator::Hugepages = 1;
+  }
+
+
   if( GridCmdOptionExists(*argv,*argv+*argc,"--debug-signals") ){
     Grid_debug_handler_init();
   }
@@ -304,6 +309,7 @@ void Grid_init(int *argc,char ***argv)
     std::cout<<GridLogMessage<<"  --threads n     : default number of OMP threads"<<std::endl;
     std::cout<<GridLogMessage<<"  --grid n.n.n.n  : default Grid size"<<std::endl;
     std::cout<<GridLogMessage<<"  --shm  M        : allocate M megabytes of shared memory for comms"<<std::endl;
+    std::cout<<GridLogMessage<<"  --shm-hugepages : use explicit huge pages in mmap call "<<std::endl;    
     std::cout<<GridLogMessage<<std::endl;
     std::cout<<GridLogMessage<<"Verbose and debug:"<<std::endl;
     std::cout<<GridLogMessage<<std::endl;
@@ -317,7 +323,7 @@ void Grid_init(int *argc,char ***argv)
     std::cout<<GridLogMessage<<std::endl;
     std::cout<<GridLogMessage<<"  --comms-concurrent : Asynchronous MPI calls; several dirs at a time "<<std::endl;    
     std::cout<<GridLogMessage<<"  --comms-sequential : Synchronous MPI calls; one dirs at a time "<<std::endl;    
-    std::cout<<GridLogMessage<<"  --comms-overlap : Overlap comms with compute "<<std::endl;    
+    std::cout<<GridLogMessage<<"  --comms-overlap    : Overlap comms with compute "<<std::endl;    
     std::cout<<GridLogMessage<<std::endl;
     std::cout<<GridLogMessage<<"  --dslash-generic: Wilson kernel for generic Nc"<<std::endl;    
     std::cout<<GridLogMessage<<"  --dslash-unroll : Wilson kernel for Nc=3"<<std::endl;    
@@ -356,12 +362,13 @@ void Grid_init(int *argc,char ***argv)
   if( GridCmdOptionExists(*argv,*argv+*argc,"--comms-sequential") ){
     CartesianCommunicator::SetCommunicatorPolicy(CartesianCommunicator::CommunicatorPolicySequential);
   }
+
   if( GridCmdOptionExists(*argv,*argv+*argc,"--lebesgue") ){
     LebesgueOrder::UseLebesgueOrder=1;
   }
   CartesianCommunicator::nCommThreads = -1;
-  if( GridCmdOptionExists(*argv,*argv+*argc,"--commthreads") ){
-    arg= GridCmdOptionPayload(*argv,*argv+*argc,"--commthreads");
+  if( GridCmdOptionExists(*argv,*argv+*argc,"--comms-threads") ){
+    arg= GridCmdOptionPayload(*argv,*argv+*argc,"--comms-threads");
     GridCmdOptionInt(arg,CartesianCommunicator::nCommThreads);
   }
   if( GridCmdOptionExists(*argv,*argv+*argc,"--cacheblocking") ){
@@ -378,7 +385,10 @@ void Grid_init(int *argc,char ***argv)
 		  Grid_default_latt,
 		  Grid_default_mpi);
 
-  std::cout << GridLogDebug << "Requesting "<< CartesianCommunicator::MAX_MPI_SHM_BYTES <<" byte stencil comms buffers "<<std::endl;
+  std::cout << GridLogMessage << "Requesting "<< CartesianCommunicator::MAX_MPI_SHM_BYTES <<" byte stencil comms buffers "<<std::endl;
+  if ( CartesianCommunicator::Hugepages) {
+    std::cout << GridLogMessage << "Mapped stencil comms buffers as MAP_HUGETLB "<<std::endl;
+  }
 
   if( GridCmdOptionExists(*argv,*argv+*argc,"--decomposition") ){
     std::cout<<GridLogMessage<<"Grid Default Decomposition patterns\n";