X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/eb637bd7e0c8b1dc75b0d7cd1ec199b097134d34..739ef71fe22da81ca46a254e74bbba851825f9dc:/ChangeLog

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 ----------------------------------------------------------------------------
 
-SimGrid (3.28.1) NOT RELEASED YET (v3.29 expected September 22. 2021, 19:21 UTC)
+SimGrid (3.29) October 7. 2021
+
+The "Ask a stupid question" release.
+
+We wish that every user ask one question about SimGrid to celebrate.
+On Mattermost, Stack Overflow or using the issues tracker.
+
 
 New modeling features:
- - Non-linear resource sharing for decay models:
-   - The total capacity may depend on the number of concurrent usages
-   - For that, resources can take a callback that computes the capacity 
-     depending on the idle capacity and the number of concurrent usages
+ - Non-linear resource sharing, modeling resources whose performance heavily degrades with contention:
+   - The total capacity may be updated dynamically through a callback
+     and depends mainly on the number of concurrent flows.
    - Examples (both cpp and python): io-degradation, network-nonlinear, exec-cpu-nonlinear
 
- - Dynamic factors for CPU and disk: similarly to dynamic network factors,
-   allows the user to set a callback which can affect the progress of activities
-   (multiplicative factor applied when updating the amount of work remaining).
-   - Example: examples/cpp/exec-cpu-factors
+ - Dynamic factors: model variability in the speed of activities
+    - Each action can now have a factor that affects its progression.
+      This multiplicative factor is applied when updating the amount of work
+      remaining, thereby an activity with factor=0.5 only uses half of the
+      instantaneous power/bandwidth it is allocated and will appear twice
+      slower than what it actually consumes.
+    - This can be used to model a overhead (e.g., there is a 20 bytes
+      header in a 480 bytes TCP packet so the factor 0.9583) but the novelty
+      is this factor can now easily be adjusted depending on activity's and
+      resources characteristics.
+    - This existed for network (e.g., the effective bandwidth depends
+      on the message in SMPI piecewise-linear network model) but it is now
+      more general (the factor may depend on the source and destination and
+      thus account to different behaviors for intra-node communications and
+      extra-node communications) and is available for CPUs (e.g., if you
+      want to model an affinity as in the "Unrelated Machines" problem in
+      scheduling) and disks (e.g., if you want to model a stochastic
+      capacity) too.
+    - For that, resources can be provided with a callback that computes
+      the activity factor when creating the action.
+    - Example: examples/cpp/exec-cpu-factors
+    - The same mechanism is also available for the latency, which
+      allows to easily introduce complex variability patterns.
 
 Python:
  - Added support to programmatic platform creation in Python.
@@ -28,6 +52,9 @@ SMPI:
    - scan/excan can now be replayed
    - wait action now uses ranks and not pid, as the other ones.
    - smpi/init and smpi/finalization-barrier are now valid for replays.
+ - exit() is now intercepted by SMPI to avoid premature shutdown of
+   simulation. First non 0 return codes is returned as simulation return
+   code.
 
 Documentation:
   * New section "Release Notes" documenting recent and current developments.