fwi: merge mpi pure experiment

The getResources function is used to assign the proper cpu binding
depending on the version. However, additional contraints are required to
ensure that we have enough points in Y.

By default the mpi+send+seq branch is disabled.

garlic/exp/fwi/common.nix

@@ -31,6 +31,15 @@ rec {
     # join branch, even if we have multiple blocksizes.
     unique (map fixBlocksize allConfigs);
 
+  getResources = {gitBranch, hw}:
+  if (gitBranch == "garlic/mpi+send+seq") then {
+    cpusPerTask = hw.cpusPerSocket;
+    ntasksPerNode = hw.socketsPerNode;
+  } else {
+    cpusPerTask = 1;
+    ntasksPerNode = hw.cpusPerNode;
+  };
+
   exec = {nextStage, conf, ...}: stages.exec {
     inherit nextStage;