Thoroughly document unit/send-get/strided_sendget.f90.

Use only the needed number of images for the testing strided_sendget.

Author: vehre

CMakeLists.txt

@@ -213,7 +213,7 @@ if(opencoarrays_aware_compiler)
   add_mpi_test(get_with_offset_1d 2 ${tests_root}/unit/send-get/get_with_offset_1d)
   add_mpi_test(whole_get_array 2 ${tests_root}/unit/send-get/whole_get_array)
   add_mpi_test(strided_get 2 ${tests_root}/unit/send-get/strided_get)
-  add_mpi_test(strided_sendget 4 ${tests_root}/unit/send-get/strided_sendget)
+  add_mpi_test(strided_sendget 3 ${tests_root}/unit/send-get/strided_sendget)
   add_mpi_test(co_sum 4 ${tests_root}/unit/collectives/co_sum_test)
   add_mpi_test(co_broadcast 4 ${tests_root}/unit/collectives/co_broadcast_test)
   add_mpi_test(co_min 4 ${tests_root}/unit/collectives/co_min_test)

src/tests/unit/send-get/strided_sendget.f90

@@ -1,67 +1,105 @@
+! Test that sendget with strides on either side (of the assignment) works
+! as expected.
+!
+! This test needs at least three images, because sendget has the potential
+! to check whether on image used in the communication is the current one.
+! More than three images do not pay, because there is no general code in
+! this test.
+!
 ! Written by Andre Vehreschild
+
 program stridedsendgettest
 
   implicit none
 
+  integer, parameter :: src_image = 2, dst_image = 3, master_image = 1
   integer, save, dimension(4,6) :: srcmat[*], dstmat[*]
   integer, save, dimension(6) :: srcvec[*], dstvec[*]
   integer :: i
   logical :: test_passed = .true.
 
-  if (this_image() == 2) then
+  ! Make sure that enough images are available for this test.
+  ! Everything less than dst_image == 3 may make sendget use an
+  ! optimized version saving a part of the communication, which is
+  ! not what the test should test.
+  if (num_images() < dst_image) error stop "Need at least three images."
+
+  ! On the src_image, set some defined values, to be able to distinguish
+  ! strides going wrong.
+  if (this_image() == src_image) then
     srcvec = [(2 * i, i = 1, 6)]
     srcmat = reshape([(i * 2, i = 1, 4*6)], [4,6])
-  elseif (this_image() == 3) then
+  ! On the dst_image set values that enable to recognize unset values.
+  elseif (this_image() == dst_image) then
     dstmat = -1
     dstvec = -2
   end if
 
+  ! Make sure data is valid on all images.
   sync all
-  if (this_image() == 1) then
-    dstvec(:)[3] = srcvec(:)[2]
-    dstmat(3,:)[3] = srcvec(:)[2]
+
+  ! master_image is the controller in this communication and therefore needs
+  ! to initiate the communication. 
+  if (this_image() == master_image) then
+    ! Transfer data from the src-vector to the dst-vector on image
+    ! dst_image.  This is a transfer of a contingous block of data and here for
+    ! completeness only.
+    dstvec(:)[dst_image] = srcvec(:)[src_image]
+    ! This statement uses a stride in the send phase of the communication.
+    dstmat(3,:)[dst_image] = srcvec(:)[src_image]
   end if
 
+  ! Make sure the communication has completed.
   sync all
-  if (this_image() == 3) then
-    if (any(dstvec(:) /= [2, 4, 6, 8, 10, 12])) then
-      print *, dstvec(:)
-      print *, "SendGet vec/vec does not match."
-!      error stop "SendGet vec/vec does not match."
-      test_passed = .false.
-    end if
 
-    if (any(dstmat(3,:) /= [2, 4, 6, 8, 10, 12])) then
-      print *, dstmat(3,:)
-      print *, "SendGet matrow/vec does not match."
-!      error stop "SendGet matrow/vec does not match."
-      test_passed = .false.
+  ! Check the result of communication on the dst_image.
+  if (this_image() == dst_image) then
+    ! Check that transfering to the vector has succeeded.
+    if (any(dstvec /= [2, 4, 6, 8, 10, 12])) error stop "SendGet vec/vec does not match."
+
+    ! Check that transfering a vector into a matrix changes only the
+    ! values desired.
+    if (any(dstmat /= reshape([-1, -1,  2, -1, &
+                               -1, -1,  4, -1, &
+                               -1, -1,  6, -1, &
+                               -1, -1,  8, -1, &
+                               -1, -1, 10, -1, &
+                               -1, -1, 12, -1], [4, 6]))) then
+      error stop "SendGet matrow/vec does not match."
     end if
+    ! Reset the dst-buffers to enable new test.
+    dstvec = -2
+    dstmat = -1
   end if
 
+  ! Wait for dst having done its tests.
   sync all
-  if (this_image() == 1) then
-    dstvec(:)[3] = srcmat(2,:)[2]
-    dstmat(3,:)[3] = srcmat(2,:)[2]
+  if (this_image() == master_image) then
+    ! Execute strided get in sendget and store in a vector to just
+    ! test the get.
+    dstvec(:)[dst_image] = srcmat(2,:)[src_image]
+    ! Test both strided get and strided send at once.
+    dstmat(3,:)[dst_image] = srcmat(2,:)[src_image]
   end if
 
+  ! Ensure that the communication is all done.
   sync all
-  if (this_image() == 3) then
-    if (any(dstvec(:) /= [4, 12, 20, 28, 36, 44])) then
-      print *, dstvec(:)
-      print *, "SendGet vec/matrow does not match."
-!      error stop "SendGet vec/matrow does not match."
-      test_passed = .false.
-    end if
+  if (this_image() == dst_image) then
+    ! Check, that the strided get has the expected result.
+    if (any(dstvec /= [4, 12, 20, 28, 36, 44])) error stop "SendGet vec/matrow does not match."
 
-    if (any(dstmat(3,:) /= [4, 12, 20, 28, 36, 44])) then
-      print *, dstmat(3,:)
-      print *, "SendGet matrow/matrow does not match."
-!      error stop "SendGet matrow/matrow does not match."
-      test_passed = .false.
+    ! And that both communications with stride work as expected.   
+    if (any(dstmat /= reshape([-1, -1,  4, -1, &
+                               -1, -1, 12, -1, &
+                               -1, -1, 20, -1, &
+                               -1, -1, 28, -1, &
+                               -1, -1, 36, -1, &
+                               -1, -1, 44, -1], [4, 6]))) then
+      error stop "SendGet matrow/matrow does not match."
     end if
 
-    if (test_passed) print *, "Test passed"
+    ! Above checks would stop with an error on failure, so its save
+    ! to unguardedly print here, when all tests pass.
+    print *, "Test passed"
   end if
-
 end program