Changes between Version 9 and Version 10 of ticket/0829

Timestamp:

2011-06-03T15:06:30+02:00 (13 years ago)

Author:

rblod

Comment:

--

ticket/0829

@@ -117 +117 @@
 }}}
 It was implemented in wrk_nemo_2 and implemented for test in traadv_tvd. To avoid changing all routines before a definitive choice, we choose to keep the old way and duplicate wrk_nemo in wrk_nemo_2 (later saved as wrk_nemo_2_simple), so we declare the double amount of memory, this would of course not be the case if it was implemented in all routines[[BR]]
-To avoid memory leaks, we could check for instance at the end of step that each counter is equal to one.
+To avoid memory leaks, we could check for instance at the end of step that each counter is equal to one.[[BR]]
+This was implemented here : http://forge.ipsl.jussieu.fr/nemo/changeset/2775
 
 ==== 3- Dynamic dynamic memory ====
@@ -123 +124 @@
 The point here is to avoid to have hard-coded the maximum of potential work arrays in use, and to optimize the memory size, especially for applications expensive in memory (biogeochemistry, assimilation)[[BR]]
 Here again, as a preliminary test, the implementation is done is w and the previous one is renamed wrk_nemo_2_simple.[[BR]]
-For each type of work arrays, we use an associated chained list to build the working arrays needed. But when we exit a routine, we do not destroy the working array created but we just point back to the beginning of the list. Actually at the end of the first time step we should have built all the memory needed. 
+For each type of work arrays, we use an associated chained list to build the working arrays needed. But when we exit a routine, we do not destroy the working array created but we just point back to the beginning of the list. If the following routine need one array more, we just add an element in the chain. Actually at the end of the first time step we should have built exactly  the total amount of memory needed. 
+{{{
+   TYPE work_space_3d
+     LOGICAL ::  in_use
+     INTEGER :: indic
+     REAL(wp), DIMENSION(:,:,:), POINTER :: wrk
+     TYPE (work_space_3d), POINTER :: next => NULL()
+     TYPE (work_space_3d), POINTER :: prev => NULL()
+   END TYPE
+   TYPE(work_space_3d), POINTER :: s_wrk_3d_root, s_wrk_3d
+}}}
+Then same way than above
+Then in each routine, we declare local arrays as pointers
+{{{
+ REAL(wp), DIMENSION (:,:,:), POINTER ::   zwi, zwz
 
+ CALL nemo_allocate(zwi)     ! begin routine
+ CALL nemo_deallocate(zwi)     ! to come back 
+}}}
+
+At his point, this looks very nice, but I'm questioning myself if we shouldn't simply use a standard dynamic memory implementation. I guess the answer can be formulated in term of performances :
+ * is it more expensive to allocate/deallocate at each call 
+ * or to CALL a subroutine pointing toward an existing allocated array
 
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