[!310] Change scaling of autotune results

Merge branch 'experiments/autotune' into 'master'

ref:extensions/dune-codegen The scaling of the autotune results was bugged.

See merge request [extensions/dune-codegen!310]

  [extensions/dune-codegen!310]: gitlab.dune-project.org/extensions/dune-codegen/merge_requests/310

python/dune/codegen/sumfact/autotune.py

@@ -167,7 +167,8 @@ def generate_standalone_code(sf, filename):
                       ])
 
         # Add the implementation of the kernel.
-        f.write("  for(int i=0; i<{}; ++i)\n".format(int(1e9 / sf.operations)))
+        repeats = int(1e9 / sf.operations)
+        f.write("  for(int i=0; i<{}; ++i)\n".format(repeats))
         f.write("  {\n")
         for line in knl.member.lines[1:]:
             f.write("    {}\n".format(line))
@@ -177,7 +178,7 @@ def generate_standalone_code(sf, filename):
         f.writelines(["  auto stop = Dune::PDELab::TSC::stop();\n",
                       "  std::ofstream file;\n",
                       "  file.open(argv[1]);\n",
-                      "  file << Dune::PDELab::TSC::elapsed(start, stop) << std::endl;\n",
+                      "  file << Dune::PDELab::TSC::elapsed(start, stop) / {} << std::endl;\n".format(str(float(repeats))),
                       "  file.close();\n",
                       "  accum += output[dis(rng)];\n",
                       "  std::cout << accum;\n",