-Process parameters:
+Process parameters
+==================
- initial_load [neighbors...]
+The process parameters are: initial_load [neighbors...]
-Communications:
- - two channels per host: normal and low_latency
+Communications
+==============
-How shall we manage link failures ?
+There are two receiving channels per host: control for information
+messages, and data for load transfers.
-Process model (?)
+Process model
+=============
- while (there is something to do) {
- compute some task;
- get received tasks;
- compute load balancing;
- send tasks to neighbors;
- }
+Each process is made of 3 threads: a receiver thread, a computing
+thread, and a load-balancer thread.
- * Open Questions :
- - definition of load on heterogeneous hosts?
- - how to detect convergence?
- : No need to detect convergence. Computation stops when there
- nothing more to do.
+* Receiver thread
+ ---------------
- - how to manage link failures?
+ Loop
+ | wait for a message to come, either on data channel, or on ctrl channel
+ | push received message in a buffer of received messages
+ | -> ctrl messages on the one side
+ | -> data messages on the other side
+ +-
- - shall we retrieve pending tasks?
- : Ideally, why shall. How? By using some acknowledgment?
+ The loop terminates when a "finalize" message is received on each
+ channel.
+
+* Computing thread
+ ----------------
+
+ Loop
+ | if we received some real load, get it (data messages)
+ | if there is some real load to send, send it
+ | if we own some load, simulate some computing on it
+ | sleep a bit if we are looping too fast
+ +-
+ send CLOSE on data for all neighbors
+ wait for CLOSE on data from all neighbors
+
+ The loop terminates when process::still_running() returns false.
+ (read the source for full details...)
+
+* Load-balancing thread
+ ---------------------
+
+ Loop
+ | call load-balancing algorithm
+ | send ctrl messages
+ | sleep (min_lb_iter_duration)
+ | receive ctrl messages
+ +-
+ send CLOSE on ctrl for all neighbors
+ wait for CLOSE on ctrl from all neighbors
+
+ The loop terminates when process::still_running() returns false.
+ (read the source for full details...)
+
+Some notes about *load attributes
+=================================
+process::real_load Current *real* load.
+ Used for the computations.
+ Displayed in log messages.
+
+process::expected_load Current load estimation.
+ Used for load-balancing estimation, and for
+ diffusing to neighbors.
+ * Without bookkeeping, it equals real_load
+ minus pending sends.
+ * With bookkeeping, it corresponds to the
+ "virtual load".
