7 changed files with 667 additions and 63 deletions
--- a/Grid/Benchmark_Grid.cpp
+++ b/Grid/Benchmark_Grid.cpp
@ -73,6 +73,8 @@ class Benchmark
        {local[0] * mpi[0], local[1] * mpi[1], local[2] * mpi[2], local[3] * mpi[3]});
    GridCartesian *TmpGrid = SpaceTimeGrid::makeFourDimGrid(
        latt4, GridDefaultSimd(Nd, vComplex::Nsimd()), GridDefaultMpi());
+    Grid::Coordinate shm;
+    GlobalSharedMemory::GetShmDims(mpi, shm);

    uint64_t NP = TmpGrid->RankCount();
    uint64_t NN = TmpGrid->NodeCount();
@ -85,7 +87,9 @@ class Benchmark
    std::cout << GridLogMessage << "* OpenMP threads : " << GridThread::GetThreads()
              << std::endl;

-    std::cout << GridLogMessage << "* MPI tasks      : " << GridCmdVectorIntToString(mpi)
+    std::cout << GridLogMessage << "* MPI layout     : " << GridCmdVectorIntToString(mpi)
+              << std::endl;
+    std::cout << GridLogMessage << "* Shm layout     : " << GridCmdVectorIntToString(shm)
              << std::endl;

    std::cout << GridLogMessage << "* vReal          : " << sizeof(vReal) * 8 << "bits ; "
@ -118,6 +122,7 @@ class Benchmark
    for (unsigned int i = 0; i < mpi.size(); ++i)
    {
      tmp["mpi"].push_back(mpi[i]);
+      tmp["shm"].push_back(shm[i]);
    }
    tmp["ranks"] = NP;
    tmp["nodes"] = NN;
@ -132,6 +137,8 @@ class Benchmark

    Coordinate simd_layout = GridDefaultSimd(Nd, vComplexD::Nsimd());
    Coordinate mpi_layout = GridDefaultMpi();
+    Coordinate shm_layout;
+    GlobalSharedMemory::GetShmDims(mpi_layout, shm_layout);

    for (int mu = 0; mu < Nd; mu++)
      if (mpi_layout[mu] > 1)
@ -143,8 +150,8 @@ class Benchmark
    std::cout << GridLogMessage << "Benchmarking threaded STENCIL halo exchange in "
              << nmu << " dimensions" << std::endl;
    grid_small_sep();
-    grid_printf("%5s %5s %15s %15s %15s %15s %15s\n", "L", "dir", "payload (B)",
-                "time (usec)", "rate (GB/s/node)", "std dev", "max");
+    grid_printf("%5s %5s %7s %15s %15s %15s %15s %15s\n", "L", "dir", "shm",
+                "payload (B)", "time (usec)", "rate (GB/s/node)", "std dev", "max");

    for (int lat = 16; lat <= maxlat; lat += 8)
    {
@ -173,74 +180,80 @@ class Benchmark
      for (int dir = 0; dir < 8; dir++)
      {
        int mu = dir % 4;
-        if (mpi_layout[mu] > 1)
+        if (mpi_layout[mu] == 1) // skip directions that are not distributed
+          continue;
+        bool is_shm = mpi_layout[mu] == shm_layout[mu];
+        bool is_partial_shm = !is_shm && shm_layout[mu] != 1;
+
+        std::vector<double> times(Nloop);
+        for (int i = 0; i < NWARMUP; i++)
+        {
+          int xmit_to_rank;
+          int recv_from_rank;
+
+          if (dir == mu)
+          {
+            int comm_proc = 1;
+            Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
+          }
+          else
+          {
+            int comm_proc = mpi_layout[mu] - 1;
+            Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
+          }
+          Grid.SendToRecvFrom((void *)&xbuf[dir][0], xmit_to_rank, (void *)&rbuf[dir][0],
+                              recv_from_rank, bytes);
+        }
+        for (int i = 0; i < Nloop; i++)
        {

-          std::vector<double> times(Nloop);
-          for (int i = 0; i < NWARMUP; i++)
+          dbytes = 0;
+          double start = usecond();
+          int xmit_to_rank;
+          int recv_from_rank;
+
+          if (dir == mu)
          {
-            int xmit_to_rank;
-            int recv_from_rank;
-
-            if (dir == mu)
-            {
-              int comm_proc = 1;
-              Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
-            }
-            else
-            {
-              int comm_proc = mpi_layout[mu] - 1;
-              Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
-            }
-            Grid.SendToRecvFrom((void *)&xbuf[dir][0], xmit_to_rank,
-                                (void *)&rbuf[dir][0], recv_from_rank, bytes);
+            int comm_proc = 1;
+            Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
          }
-          for (int i = 0; i < Nloop; i++)
+          else
          {
-
-            dbytes = 0;
-            double start = usecond();
-            int xmit_to_rank;
-            int recv_from_rank;
-
-            if (dir == mu)
-            {
-              int comm_proc = 1;
-              Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
-            }
-            else
-            {
-              int comm_proc = mpi_layout[mu] - 1;
-              Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
-            }
-            Grid.SendToRecvFrom((void *)&xbuf[dir][0], xmit_to_rank,
-                                (void *)&rbuf[dir][0], recv_from_rank, bytes);
-            dbytes += bytes;
-
-            double stop = usecond();
-            t_time[i] = stop - start; // microseconds
+            int comm_proc = mpi_layout[mu] - 1;
+            Grid.ShiftedRanks(mu, comm_proc, xmit_to_rank, recv_from_rank);
          }
-          timestat.statistics(t_time);
+          Grid.SendToRecvFrom((void *)&xbuf[dir][0], xmit_to_rank, (void *)&rbuf[dir][0],
+                              recv_from_rank, bytes);
+          dbytes += bytes;

-          dbytes = dbytes * ppn;
-          double bidibytes = 2. * dbytes;
-          double rate = bidibytes / (timestat.mean / 1.e6) / 1024. / 1024. / 1024.;
-          double rate_err = rate * timestat.err / timestat.mean;
-          double rate_max = rate * timestat.mean / timestat.min;
-          grid_printf("%5d %5d %15d %15.2f %15.2f %15.1f %15.2f\n", lat, dir, bytes,
-                      timestat.mean, rate, rate_err, rate_max);
-          nlohmann::json tmp;
-          nlohmann::json tmp_rate;
-          tmp["L"] = lat;
-          tmp["dir"] = dir;
-          tmp["bytes"] = bytes;
-          tmp["time_usec"] = timestat.mean;
-          tmp_rate["mean"] = rate;
-          tmp_rate["error"] = rate_err;
-          tmp_rate["max"] = rate_max;
-          tmp["rate_GBps"] = tmp_rate;
-          json_results["comms"].push_back(tmp);
+          double stop = usecond();
+          t_time[i] = stop - start; // microseconds
        }
+        timestat.statistics(t_time);
+
+        dbytes = dbytes * ppn;
+        double bidibytes = 2. * dbytes;
+        double rate = bidibytes / (timestat.mean / 1.e6) / 1024. / 1024. / 1024.;
+        double rate_err = rate * timestat.err / timestat.mean;
+        double rate_max = rate * timestat.mean / timestat.min;
+        grid_printf("%5d %5d %7s %15d %15.2f %15.2f %15.1f %15.2f\n", lat, dir,
+                    is_shm           ? "yes"
+                    : is_partial_shm ? "partial"
+                                     : "no",
+                    bytes, timestat.mean, rate, rate_err, rate_max);
+        nlohmann::json tmp;
+        nlohmann::json tmp_rate;
+        tmp["L"] = lat;
+        tmp["dir"] = dir;
+        tmp["shared_mem"] = is_shm;
+        tmp["partial_shared_mem"] = is_partial_shm;
+        tmp["bytes"] = bytes;
+        tmp["time_usec"] = timestat.mean;
+        tmp_rate["mean"] = rate;
+        tmp_rate["error"] = rate_err;
+        tmp_rate["max"] = rate_max;
+        tmp["rate_GBps"] = tmp_rate;
+        json_results["comms"].push_back(tmp);
      }
      for (int d = 0; d < 8; d++)
      {
--- a/Quda/.clang-format
+++ b/Quda/.clang-format
@ -0,0 +1,14 @@
+{
+  BasedOnStyle: LLVM,
+  UseTab: Never,
+  IndentWidth: 2,
+  TabWidth: 2,
+  BreakBeforeBraces: Allman,
+  AllowShortIfStatementsOnASingleLine: false,
+  IndentCaseLabels: false,
+  ColumnLimit: 90,
+  AccessModifierOffset: -4,
+  NamespaceIndentation: All,
+  FixNamespaceComments: false,
+  SortIncludes: true,
+}
--- a/Quda/Benchmark_Quda.cpp
+++ b/Quda/Benchmark_Quda.cpp
@ -0,0 +1,458 @@
+#include <algorithm>
+#include <array>
+#include <blas_quda.h>
+#include <cassert>
+#include <chrono>
+#include <color_spinor_field.h>
+#include <communicator_quda.h>
+#include <dirac_quda.h>
+#include <fstream>
+#include <gauge_tools.h>
+#include <memory>
+#include <mpi.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+// remove to use QUDA's own flop counting instead of Grid's convention
+#define FLOP_COUNTING_GRID
+
+#include "json.hpp"
+using nlohmann::json;
+json json_results;
+
+using namespace quda;
+
+// thanks chatGPT :)
+std::string get_timestamp()
+{
+  // Get the current time
+  auto now = std::chrono::system_clock::now();
+
+  // Convert the current time to a time_t object
+  std::time_t currentTime = std::chrono::system_clock::to_time_t(now);
+
+  // Format the time using std::put_time
+  std::stringstream ss;
+  ss << std::put_time(std::localtime(&currentTime), "%Y%m%d %H:%M:%S");
+
+  return ss.str();
+}
+
+// This is the MPI grid, i.e. the layout of ranks
+int nranks = -1;
+std::array<int, 4> mpi_grid = {1, 1, 1, 1};
+
+// run f() in a loop for roughly target_time seconds
+// returns seconds per iteration it took
+template <class F> double bench(F const &f, double target_time, int niter_warmup = 5)
+{
+  device_timer_t timer;
+  timer.start();
+  for (int iter = 0; iter < niter_warmup; ++iter)
+    f();
+  timer.stop();
+
+  double secs = timer.last() / niter_warmup;
+  int niter = std::max(1, int(target_time / secs));
+  // niter = std::min(1000, niter);
+  // printfQuda("during warmup took %f s/iter, deciding on %d iters\n", secs, niter);
+
+  // important: each rank has its own timer, so their measurements can slightly vary. But
+  // 'niter' needs to be consistent (bug took me a couple hours to track down)
+  comm_broadcast_global(&niter, sizeof(niter), 0);
+
+  timer.reset(__FUNCTION__, __FILE__, __LINE__);
+  timer.start();
+  for (int iter = 0; iter < niter; ++iter)
+    f();
+  timer.stop();
+  return timer.last() / niter;
+}
+
+void initComms(int argc, char **argv)
+{
+  // init MPI communication
+  MPI_Init(&argc, &argv);
+
+  MPI_Comm_size(MPI_COMM_WORLD, &nranks);
+  assert(1 <= nranks && nranks <= 100000);
+
+  mpi_grid[3] = nranks;
+
+  // this maps coordinates to rank number
+  auto lex_rank_from_coords = [](int const *coords, void *)
+  {
+    int rank = coords[0];
+    for (int i = 1; i < 4; i++)
+      rank = mpi_grid[i] * rank + coords[i];
+    return rank;
+  };
+
+  initCommsGridQuda(4, mpi_grid.data(), lex_rank_from_coords, nullptr);
+
+  for (int d = 0; d < 4; d++)
+    if (mpi_grid[d] > 1)
+      commDimPartitionedSet(d);
+
+  json_results["geometry"]["ranks"] = nranks;
+  json_results["geometry"]["mpi"] = mpi_grid;
+}
+
+// creates a random gauge field. L = local(!) size
+cudaGaugeField make_gauge_field(int L)
+{
+  GaugeFieldParam param;
+
+  // dimension and type of the lattice object
+  param.nDim = 4;
+  param.x[0] = L;
+  param.x[1] = L;
+  param.x[2] = L;
+  param.x[3] = L;
+
+  // number of colors. potentially confusingly, QUDA sometimes uses the word "color" to
+  // things unrelated with physical color. things like "nColor=32" do pop up in deflation
+  // solvers where it (to my understanding) refers to the number of (parallely processed)
+  // deflation vectors.
+  param.nColor = 3;
+
+  // boundary conditions (dont really care for benchmark)
+  param.t_boundary = QUDA_PERIODIC_T;
+
+  // for this benchmark we only need "SINGLE" and/or "DOUBLE" precision. But smaller
+  // precisions are available in QUDA too
+  param.setPrecision(QUDA_SINGLE_PRECISION);
+
+  // no even/odd subset, we want a full lattice
+  param.siteSubset = QUDA_FULL_SITE_SUBSET;
+
+  // what kind of 3x3 matrices the field contains. A proper gauge field has SU(3)
+  // matrices, but (for example) smeared/thick links could have non-unitary links.
+  param.link_type = QUDA_SU3_LINKS;
+
+  // "NULL" does not initialize the field upon creation, "ZERO" would set everything to 0
+  param.create = QUDA_NULL_FIELD_CREATE;
+
+  // field should be allocated directly on the accelerator/GPU
+  param.location = QUDA_CUDA_FIELD_LOCATION;
+
+  // "reconstruct" here means reconstructing a SU(3) matrix from fewer than 18 real
+  // numbers (=3x3 complex numbers). Great feature in production (saving
+  // memory/cache/network bandwidth), not used for this benchmark.
+  param.reconstruct = QUDA_RECONSTRUCT_NO;
+
+  // "ghostExchange" would often be called "halo exchange" outside of Quda. This has
+  // nothing to do with ghost fields from continuum/perturbative qcd.
+  param.ghostExchange = QUDA_GHOST_EXCHANGE_NO;
+
+  // This controls the physical order of elements. "float2" is the the default
+  param.order = QUDA_FLOAT2_GAUGE_ORDER;
+
+  // this means the field is a LORENTZ vector (which a gauge field must be). Has nothing
+  // to do with spin.
+  param.geometry = QUDA_VECTOR_GEOMETRY;
+
+  // create the field and fill with random SU(3) matrices
+  // std::cout << param << std::endl; // double-check parameters
+  auto U = cudaGaugeField(param);
+  gaugeGauss(U, /*seed=*/1234, 1.0);
+  return U;
+}
+
+// create a random source vector (L = local size)
+ColorSpinorField make_source(int L, int Ls = 1)
+{
+  // NOTE: `param.x` directly determines the size of the (local, per rank) memory
+  // allocation. Thus for checkerboarding, we have to specifly x=(L/2,L,L,L) to get a
+  // physical local volume of L^4, thus implicity choosing a dimension for the
+  // checkerboarding (shouldnt really matter of course which one).
+  ColorSpinorParam param;
+  param.nColor = 3;
+  param.nSpin = 4;
+  param.nVec = 1; // only a single vector
+  param.pad = 0;
+  param.siteSubset = QUDA_PARITY_SITE_SUBSET;
+  param.nDim = Ls == 1 ? 4 : 5;
+  param.x[0] = L / 2;
+  param.x[1] = L;
+  param.x[2] = L;
+  param.x[3] = L;
+  param.x[4] = Ls;
+  param.pc_type = QUDA_4D_PC;
+  param.siteOrder = QUDA_EVEN_ODD_SITE_ORDER;
+
+  // somewhat surprisingly, the DiracWilson::Dslash(...) function only works with the
+  // UKQCD_GAMMA_BASIS
+  param.gammaBasis = QUDA_UKQCD_GAMMA_BASIS;
+
+  param.create = QUDA_NULL_FIELD_CREATE; // do not (zero-) initilize the field
+  param.setPrecision(QUDA_SINGLE_PRECISION);
+  param.location = QUDA_CUDA_FIELD_LOCATION;
+
+  // create the field and fill it with random values
+  auto src = ColorSpinorField(param);
+  quda::RNG rng(src, 1234);
+  spinorNoise(src, rng, QUDA_NOISE_GAUSS);
+  /*printfQuda(
+      "created src with norm = %f (sanity check: should be close to %f) and %f bytes\n",
+      blas::norm2(src), 2.0 * 12 * geom[0] * geom[1] * geom[2] * geom[3],
+      src.Bytes() * 1.0);*/
+  // src.PrintDims();
+
+  return src;
+}
+
+void benchmark_wilson(std::vector<int> const &L_list, double target_time)
+{
+  printfQuda("==================== wilson dirac operator ====================\n");
+#ifdef FLOP_COUNTING_GRID
+  printfQuda("IMPORTANT: flop counting as in Benchmark_Grid\n");
+#else
+  printfQuda("IMPORTANT: flop counting by QUDA's own convention (different from "
+             "Benchmark_Grid)\n");
+#endif
+  printfQuda("%5s %15s %15s\n", "L", "time (usec)", "Gflop/s/rank");
+
+  for (int L : L_list)
+  {
+    // printfQuda("starting wilson L=%d\n", L);
+
+    auto U = make_gauge_field(L);
+    auto src = make_source(L);
+
+    // create (Wilson) dirac operator
+    DiracParam param;
+    param.kappa = 0.10;
+    param.dagger = QUDA_DAG_NO;
+    param.matpcType = QUDA_MATPC_EVEN_EVEN;
+    auto dirac = DiracWilson(param);
+
+    // insert gauge field into the dirac operator
+    // (the additional nullptr's are for smeared links and fancy preconditioners and such.
+    // Not used for simple Wilson fermions)
+    dirac.updateFields(&U, nullptr, nullptr, nullptr);
+    auto res = ColorSpinorField(ColorSpinorParam(src));
+    auto f = [&]() { dirac.Dslash(res, src, QUDA_EVEN_PARITY); };
+
+    // first run to get the quda tuning out of the way
+    dirac.Flops(); // reset flops counter
+    f();
+    double flops = 1.0 * dirac.Flops();
+
+    // actual benchmarking
+    auto start_time = get_timestamp();
+    double secs = bench(f, target_time);
+    auto end_time = get_timestamp();
+
+#ifdef FLOP_COUNTING_GRID
+    // this is the flop counting from Benchmark_Grid
+    double Nc = 3;
+    double Nd = 4;
+    double Ns = 4;
+    flops = (Nc * (6 + (Nc - 1) * 8) * Ns * Nd + 2 * Nd * Nc * Ns + 2 * Nd * Nc * Ns * 2);
+    flops *= L * L * L * L / 2.0;
+#endif
+
+    printfQuda("%5d %15.2f %15.2f\n", L, secs * 1e6, flops / secs * 1e-9);
+
+    json tmp;
+    tmp["L"] = L;
+    tmp["Gflops_wilson"] = flops / secs * 1e-9;
+    tmp["start_time"] = start_time;
+    tmp["end_time"] = end_time;
+    json_results["flops"]["results"].push_back(tmp);
+  }
+}
+
+void benchmark_dwf(std::vector<int> const &L_list, double target_time)
+{
+  printfQuda("==================== domain wall dirac operator ====================\n");
+#ifdef FLOP_COUNTING_GRID
+  printfQuda("IMPORTANT: flop counting as in Benchmark_Grid\n");
+#else
+  printfQuda("IMPORTANT: flop counting by QUDA's own convention (different from "
+             "Benchmark_Grid)\n");
+#endif
+  printfQuda("%5s %15s %15s\n", "L", "time (usec)", "Gflop/s/rank");
+  int Ls = 12;
+  for (int L : L_list)
+  {
+    // printfQuda("starting dwf L=%d\n", L);
+    auto U = make_gauge_field(L);
+    auto src = make_source(L, Ls);
+
+    // create dirac operator
+    DiracParam param;
+    param.kappa = 0.10;
+    param.Ls = Ls;
+    param.m5 = 0.1;
+    param.dagger = QUDA_DAG_NO;
+    param.matpcType = QUDA_MATPC_EVEN_EVEN;
+    auto dirac = DiracDomainWall(param);
+
+    // insert gauge field into the dirac operator
+    // (the additional nullptr's are for smeared links and fancy preconditioners and such)
+    dirac.updateFields(&U, nullptr, nullptr, nullptr);
+    auto res = ColorSpinorField(ColorSpinorParam(src));
+    auto f = [&]() { dirac.Dslash(res, src, QUDA_EVEN_PARITY); };
+
+    // first run to get the quda tuning out of the way
+    dirac.Flops(); // reset flops counter
+    f();
+    double flops = 1.0 * dirac.Flops();
+
+    // actual benchmarking
+    auto start_time = get_timestamp();
+    double secs = bench(f, target_time);
+    auto end_time = get_timestamp();
+
+#ifdef FLOP_COUNTING_GRID
+    // this is the flop counting from Benchmark_Grid
+    double Nc = 3;
+    double Nd = 4;
+    double Ns = 4;
+    flops = (Nc * (6 + (Nc - 1) * 8) * Ns * Nd + 2 * Nd * Nc * Ns + 2 * Nd * Nc * Ns * 2);
+    flops *= L * L * L * L * Ls / 2.0;
+#endif
+
+    printfQuda("%5d %15.2f %15.2f\n", L, secs * 1e6, flops / secs * 1e-9);
+    json tmp;
+    tmp["L"] = L;
+    tmp["Gflops_dwf4"] = flops / secs * 1e-9;
+    tmp["start_time"] = start_time;
+    tmp["end_time"] = end_time;
+    json_results["flops"]["results"].push_back(tmp);
+  }
+}
+
+void benchmark_axpy(std::vector<int> const &L_list, double target_time)
+{
+  // number of iterations for warmup / measurement
+  // (feel free to change for noise/time tradeoff)
+  constexpr int niter_warmup = 5;
+
+  printfQuda("==================== axpy / memory ====================\n");
+
+  ColorSpinorParam param;
+  param.nDim = 4;   // 4-dimensional lattice
+  param.x[4] = 1;   // no fifth dimension
+  param.nColor = 3; // supported values for nSpin/nColor are configured when compiling
+                    // QUDA. "3*4" will probably always be enabled, so we stick with this
+  param.nSpin = 4;
+  param.nVec = 1;                            // just a single vector
+  param.siteSubset = QUDA_FULL_SITE_SUBSET;  // full lattice = no odd/even
+  param.pad = 0;                             // no padding
+  param.create = QUDA_NULL_FIELD_CREATE;     // do not (zero-) initilize the field
+  param.location = QUDA_CUDA_FIELD_LOCATION; // field should reside on GPU
+  param.setPrecision(QUDA_SINGLE_PRECISION);
+
+  // the following dont matter for an axpy benchmark, but need to choose something
+  param.pc_type = QUDA_4D_PC;
+  param.siteOrder = QUDA_EVEN_ODD_SITE_ORDER;
+  param.gammaBasis = QUDA_DEGRAND_ROSSI_GAMMA_BASIS;
+
+  printfQuda("%5s %15s %15s %15s %15s\n", "L", "size (MiB/rank)", "time (usec)",
+             "GiB/s/rank", "Gflop/s/rank");
+  for (int L : L_list)
+  {
+    // printfQuda("starting axpy L=%d\n", L);
+    //  IMPORTANT: all of `param.x`, `field_elements`, `field.Bytes()`
+    //             are LOCAL, i.e. per rank / per GPU
+
+    param.x[0] = L;
+    param.x[1] = L;
+    param.x[2] = L;
+    param.x[3] = L;
+
+    // number of (real) elements in one (local) field
+    size_t field_elements = 2 * param.x[0] * param.x[1] * param.x[2] * param.x[3] *
+                            param.nColor * param.nSpin;
+
+    // create the field(s)
+    auto fieldA = ColorSpinorField(param);
+    auto fieldB = ColorSpinorField(param);
+    assert(fieldA.Bytes() == sizeof(float) * field_elements); // sanity check
+    assert(fieldB.Bytes() == sizeof(float) * field_elements); // sanity check
+
+    // fill fields with random values
+    quda::RNG rng(fieldA, 1234);
+    spinorNoise(fieldA, rng, QUDA_NOISE_GAUSS);
+    spinorNoise(fieldB, rng, QUDA_NOISE_GAUSS);
+
+    // number of operations / bytes per iteration
+    // axpy is one addition, one multiplication, two read, one write
+    double flops = 2 * field_elements;
+    double memory = 3 * sizeof(float) * field_elements;
+
+    auto f = [&]() { blas::axpy(1.234, fieldA, fieldB); };
+
+    // first run to get the quda tuning out of the way
+    f();
+
+    // actual benchmarking
+    auto start_time = get_timestamp();
+    double secs = bench(f, target_time);
+    auto end_time = get_timestamp();
+
+    double mem_MiB = memory / 1024. / 1024.;
+    double GBps = mem_MiB / 1024 / secs;
+    printfQuda("%5d %15.2f %15.2f %15.2f %15.2f\n", L, mem_MiB, secs * 1e6, GBps,
+               flops / secs * 1e-9);
+
+    json tmp;
+    tmp["L"] = L;
+    tmp["size_MB"] = mem_MiB;
+    tmp["GBps"] = GBps;
+    tmp["GFlops"] = flops / secs * 1e-9;
+    tmp["start_time"] = start_time;
+    tmp["end_time"] = end_time;
+    json_results["axpy"].push_back(tmp);
+  }
+}
+
+int main(int argc, char **argv)
+{
+  std::string json_filename = ""; // empty indicates no json output
+  for (int i = 0; i < argc; i++)
+  {
+    if (std::string(argv[i]) == "--json-out")
+      json_filename = argv[i + 1];
+  }
+
+  initComms(argc, argv);
+
+  initQuda(-1); // -1 for multi-gpu. otherwise this selects the device to be used
+
+  //  verbosity options are:
+  //  SILENT, SUMMARIZE, VERBOSE, DEBUG_VERBOSE
+  setVerbosity(QUDA_SUMMARIZE);
+
+  printfQuda("MPI layout = %d %d %d %d\n", mpi_grid[0], mpi_grid[1], mpi_grid[2],
+             mpi_grid[3]);
+
+  benchmark_axpy({8, 12, 16, 24, 32, 48}, 1.0);
+
+  setVerbosity(QUDA_SILENT);
+  benchmark_wilson({8, 12, 16, 24, 32, 48}, 1.0);
+  benchmark_dwf({8, 12, 16, 24, 32}, 1.0);
+  setVerbosity(QUDA_SUMMARIZE);
+
+  printfQuda("==================== done with all benchmarks ====================\n");
+
+  if (!json_filename.empty())
+  {
+    printfQuda("writing benchmark results to %s\n", json_filename.c_str());
+
+    int me = 0;
+    MPI_Comm_rank(MPI_COMM_WORLD, &me);
+    if (me == 0)
+    {
+      std::ofstream json_file(json_filename);
+      json_file << std::setw(2) << json_results;
+    }
+  }
+
+  endQuda();
+  quda::comm_finalize();
+  MPI_Finalize();
+}
--- a/Quda/Readme.md
+++ b/Quda/Readme.md
@ -0,0 +1,30 @@
+# QUDA benchmarks
+
+This folder contains benchmarks for the [QUDA](https://github.com/lattice/quda) library.
+
+- `Benchmark_Quda`: This benchmark measure floating point performances of fermion
+matrices (Wilson and DWF), as well as memory bandwidth (using a simple `axpy` operation). Measurements are
+performed for a fixed range of problem sizes.
+
+## Building
+After setting up your compilation environment (Tursa: `source /home/dp207/dp207/shared/env/production/env-{base,gpu}.sh`):
+```bash
+./build-quda.sh <env_dir>          # build Quda
+./build-benchmark.sh <env_dir>     # build benchmark
+```
+where `<env_dir>` is an arbitrary directory where every product will be stored.
+
+## Running the Benchmark
+
+The benchmark should be run as
+```bash
+mpirun -np <ranks> <env_dir>/prefix/qudabench/Benchmark_Quda
+```
+where `<ranks>` is the total number of GPU's to use. On Tursa this is 4 times the number of nodes.
+
+Note:
+- on Tursa, the `wrapper.sh` script that is typically used with Grid is not necessary.
+- due to Qudas automatic tuning, the benchmark might take significantly longer to run than `Benchmark_Grid` (even though it does fewer things).
+  - setting `QUDA_ENABLE_TUNING=0` disables all tuning (degrades performance severely). By default, it is turned on.
+  - setting `QUDA_RESOURCE_PATH=<some folder>` enables Quda to save and reuse optimal tuning parameters, making repeated runs much faster
+  
--- a/Quda/build-benchmark.sh
+++ b/Quda/build-benchmark.sh
@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC1090,SC1091
+
+set -euo pipefail
+
+if (( $# != 1 )); then
+    echo "usage: $(basename "$0") <environment directory>" 1>&2
+    exit 1
+fi
+env_dir=$1
+
+# TODO: this is Tursa specific. have not figured out the correct way to do this.
+EXTRA_LIBS="/home/dp207/dp207/shared/env/versions/220428/spack/opt/spack/linux-rhel8-zen2/gcc-9.4.0/cuda-11.4.0-etxow4jb23qdbs7j6txczy44cdatpj22/lib64/stubs/libcuda.so /home/dp207/dp207/shared/env/versions/220428/spack/opt/spack/linux-rhel8-zen2/gcc-9.4.0/cuda-11.4.0-etxow4jb23qdbs7j6txczy44cdatpj22/lib64/stubs/libnvidia-ml.so"
+
+# NOTE: these flags need to be in sync with Qudas compilation options (see build-quda.sh)
+BUILD_FLAGS="-O3 -std=c++17 -DMPI_COMMS -DMULTI_GPU -DQUDA_PRECISION=12 -DQUDA_RECONSTRUCT=4"
+
+call_dir=$(pwd -P)
+script_dir="$(dirname "$(readlink -f "${BASH_SOURCE:-$0}")")"
+cd "${env_dir}"
+env_dir=$(pwd -P)
+cd "${call_dir}"
+BUILD_DIR="${env_dir}/build/Quda-benchmarks"
+PREFIX_DIR="${env_dir}/prefix/qudabench"
+QUDA_DIR=${env_dir}/prefix/quda
+mkdir -p "${BUILD_DIR}"
+mkdir -p "${PREFIX_DIR}"
+
+LINK_FLAGS="-Wl,-rpath,$QUDA_DIR/lib: $QUDA_DIR/lib/libquda.so $EXTRA_LIBS -lpthread -lmpi"
+
+g++ $BUILD_FLAGS -I$QUDA_DIR/include/targets/cuda  -I$QUDA_DIR/include   -c -o $BUILD_DIR/Benchmark_Quda.o  $script_dir/Benchmark_Quda.cpp
+g++ -g -O3 $BUILD_DIR/Benchmark_Quda.o -o $PREFIX_DIR/Benchmark_Quda $LINK_FLAGS -lmpi
--- a/Quda/build-quda.sh
+++ b/Quda/build-quda.sh
@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC1090,SC1091
+
+BUILD_FLAGS="-O3 -std=c++17"
+QUDA_FLAGS="-DQUDA_MPI=ON -DQUDA_PRECISION=14 -DQUDA_RECONSTRUCT=4 -DQUDA_GPU_ARCH=sm_80"
+
+set -euo pipefail
+
+if (( $# != 1 )); then
+    echo "usage: $(basename "$0") <environment directory>" 1>&2
+    exit 1
+fi
+env_dir=$1
+
+call_dir=$(pwd -P)
+mkdir -p ${env_dir}
+cd "${env_dir}"
+env_dir=$(pwd -P)
+cd "${call_dir}"
+
+build_dir="${env_dir}/build/quda"
+if [ -d "${build_dir}" ]; then
+    echo "error: directory '${build_dir}' exists"
+    exit 1
+fi
+mkdir -p "${build_dir}"
+
+git clone https://github.com/lattice/quda.git "${build_dir}"
+cd "${build_dir}"
+
+mkdir build; cd build
+cmake .. $QUDA_FLAGS -DCMAKE_INSTALL_PREFIX=${env_dir}/prefix/quda
+make -j128
+make install
+
+cd "${call_dir}"
--- a/Quda/env.sh
+++ b/Quda/env.sh
@ -0,0 +1,21 @@
+module load gcc/9.3.0
+module load cuda/11.4.1
+module load openmpi/4.1.1-cuda11.4
+
+export QUDA_RESOURCE_PATH=$(pwd)/tuning
+export OMP_NUM_THREADS=4
+export OMPI_MCA_btl=^uct,openib
+export OMPI_MCA_pml=ucx # by fabian. no idea what this is
+#export UCX_TLS=rc,rc_x,sm,cuda_copy,cuda_ipc,gdr_copy
+export UCX_TLS=gdr_copy,rc,rc_x,sm,cuda_copy,cuda_ipc
+export UCX_RNDV_THRESH=16384
+export UCX_RNDV_SCHEME=put_zcopy
+export UCX_IB_GPU_DIRECT_RDMA=yes
+export UCX_MEMTYPE_CACHE=n
+
+export OMPI_MCA_io=romio321
+export OMPI_MCA_btl_openib_allow_ib=true
+export OMPI_MCA_btl_openib_device_type=infiniband
+export OMPI_MCA_btl_openib_if_exclude=mlx5_1,mlx5_2,mlx5_3
+
+export QUDA_REORDER_LOCATION=GPU # this is the default anyway