Gen4MAST is a tool to automatically generate MAST models, and apply the MAST tool on them. This is a generalization using Java of the GEN4MAST prototype built using Python (http://mast.unican.es/gen4mast/). Gen4MAST is provided as open source. An executable pre-compiled jar file is also available in this link.
This is a quick tutorial of Gen4MAST. This tutorial uses the jar release of Gen4MAST that can be downloaded from here.
Gen4MAST requires the MAST tool in its binary form must be downloaded before executing Gen4MAST. MAST can be downloaded from here. Gen4MAST requires MAST version 1.4 or above.
To execute Gen4MAST, a properties file must be created. This file specifies the characteristics of the systems to be generated, and which MAST techniques to apply on them, such as schedulability analyses or priority optimizations. The properties file used in this tutorial can be downloaded [here] (https://github.com/rivasjm/gen4mast/raw/master/releases/gen4mast.properties).
Gen4MAST requires Java version 1.8. Before executing Gen4MAST, the user must modify the properties file to indicate the location of the MAST Analysis tool (mast_analysis.exe in windows). This is specified with key MAST_PATH in the provided properties file.
The properties file of this tutorial generates a synthetic pool of distributed systems using two different WCET generation methods: SCALE and UUNIFAST. This pool can be used to study the differences on schedulability of these two techniques. For this tutorial, the Offset-Based Analysis is applied to each generated system, and the results are stored in an SQLite database. Five different seeds numbers are used to generated the systems. A thread pool of size 4 is used to execute this study (parameter THREAD_POOL_SIZE of the properties file).
Gen4MAST can be launched as a standard executable java jar file as follows:
java -jar gen4mast.jar path_to_properties_file
If the path to the properties file is not provided, Gen4MAST will look for a file called "gen4mast.properties" in the current directory.
The generation and execution of this tutorial takes a few seconds, depending on the computer used.
During the execution of Gen4MAST, a directory called results will be created, in which the intermediate MAST results are stored. This results are then compiled into a SQLite database in the current directory (results.db).
After executing Gen4MAST, a SQLite database with the results is generated. This database can be accessed programatically with any programming language that supports SQLite, for example Python (sqlite3 library).
Additionally, the results database can be accessed using special purpose programs such as DB Browser for SQLite.
The properties file contains all the configuration information of Gen4MAST. It specifies among others the characteristics of the system to be generated, and which techniques to apply on them, from the techniques available in MAST (e.g. schedulability analysis, prioritity assignment, etc.).
The file follows the standard Java properties file format, in its plain text version (non XML).
Each key in the properties file can be assigned several values separated by comma. For example, parameter N_FLOWS=4,6 will generate two kinds of systems: systems with 4 end-to-end flows, and systems with 6 end-to-end flows.
All properties must be specified in the file, no defaults values are assumed.
This properties specify the characteristics of the systems to be generated.
| Property | Description |
|---|---|
| SEED | Seed to initialize the random number generator. Different seeds can be given to generate several systems with the same characteristics, but created with different seeds. Optionally, a range of seeds can be provided: SEED=1-5 is equivalent to SEED=1,2,3,4,5 |
| N_PROCESSORS | Number of processing resources in the system |
| N_FLOWS | Number of end-to-end flows in the system |
| N_TASKS | Maximum number of steps in the end-to-end flows |
| RANDOM_LENGTH | Boolean. False indicates that every end-to-end flow has N_TASKS steps. True indicates that each end-to-end flow will have a random number of steps in the range [2,N_STEPS] |
| SINGLE_FLOWS | Indicates the percentage of end-to-end flows that will have only one step (independent tasks) |
| SCHED_POLICY | Scheduling Policy used: FP for fixed priorities scheduling, or EDF for earliest deadline first scheduling |
| PERIOD_DISTRIBUTION | Probability distribution used to select the end-to-end flows periods: UNIFORM uniform distribution, LOG-UNIFORM logarithmic-uniform distribution |
| PERIOD_BASE | Minimum value that the periods can have |
| PERIOD_RATIO | Is used to indicate the maximum possible value of the periods, calculated as PERIOD_BASE * PERIOD_RATIO |
| DEADLINE | Indicates which end-to-end deadlines to assign to the end-to-end flows. If an integer is provided, the deadlines are calculated as *DEADLINE * period. Additionaly, predefined values in the segment [T, NT] are established (T and N are respectively the period and number of steps of the end-to-end flow). the predefined values are: T,NT for the limits of the range, T1,T2 for the first and second thirds of the segment, and Q1,Q2,Q3 for the first, second and third quarters of the segment |
| TASK_LOCALIZATION | Established how steps should be statically assigned to a processing resource: RANDOM assigns steps to processing resources randomly, AVOID_CONSECUTIVE avoids if possible two consecutive steps to be located in the same processing resource, AVOID_REPETITION avoids if possible that the end-to-end flows repeat a processing resource. |
| UTILIZATION | Average system utilization, given as percentage |
| UTILIZATION_BCET_FACTOR | Normalized factor to establish best-case execution times of the steps, between 0 and 1. A value of 1 indicates best-case execution times equal to worst-case execution times |
| UTILIZATION_WCET_METHOD | Method used to calculate the worst-case execution times of the steps: SCALE assings the same utilization to every step, and UUNIFAST uses the UUnifast algorithm link |
| UTILIZATION_BALANCING | Indicates the load balancing among the processing resources: BALANCED force every processing resource to have the same utilization, and with NON_BALANCED each processing resource have different utilizations |
| Property | Description |
|---|---|
| NAME | Name of this study. This value is used to identify this execution in the results database |
| WORK_PATH | Working path in which all intermediate files will be generated |
| MAST_PATH | Path of the MAST tool main executable (mast_analysis.exe in windows). Version 1.4 and above of MAST is required |
| ANALYSIS_TOOL | Which schedulability analysis tool to apply. A description of the available techniques can be found here. Available options in Gen4MAST: HOLISTIC (Holistic Analysis), OFFSET (Offset Based Approximate Analysis), OFFSET_SLANTED (Offset Based Slanted Analysis), OFFSET_OPT (Offset Based Approximate with Precedence Relations Analysis), BRUTE_FORCE (Offset Based Brute Force Analysis) |
| ASSIGNMENT_TOOL | Which scheduling parameters assignment technique to apply. A description of the available techniques can be found here. Available options in Gen4MAST: UD, ED, PD, NPD, HOSPA |
| SYNC | Boolean that indicates if the clocks of the processing resources are going to be synchronized or not. This is relevant for EDF scheduling. If clocks are syncrhonized, GC-EDF scheduling is used, otherwise LC-EDF scheudling is used. |
| HOSPA_INIT | Initial assignment used if HOSPA is used as the scheduling parameter assignment: PD, NPD |
| HOSPA_KA | Ka parameters for HOSPA |
| HOSPA_KR | Kr parameters for HOSPA |
| HOSPA_ITERATIONS | Maximum number of iterations that HOSPA is going to perform |
| HOSPA_OVERITERATIONS | Maximum number of iterations over an already schedulable solution that HOSPA is going to perform. This over-iterations further optimize the solution |
| ANALYSIS_STOP_FACTOR | The analysis stops if at any moment, any worst-case response time calculated is larger that ANALYSIS_STOP_FACTOR times the deadline |
| LC_EDF_GSD | Boolean that indicates if LC-EDF-GSD scheduling deadline assignment is used link. With LC-EDF-GSD enabled, global scheduling deadlines are assigned in LC-EDF |
| LC_EDF_DS_FACTOR | Integer that indicates the LC-EDF-DS scheduling deadline assignment factor link. The scheduling deadlines are scaled by a factor LC_EDF_DS_FACTOR |
| CALCULATE_SLACK | Boolean that enables the claculation of the system slack |
| JITTER_AVOIDANCE | Boolean that activates the emulation of a jitter avoidance technique in the schedulability analysis (not yet implemented in MAST) |
| ANALYSIS_TIMEOUT | Timeout in milliseconds of the schedulability analysis |
| Property | Description |
|---|---|
| DISPATCHER | Indicated which job dispatcher to use: LOCAL for local execution, and CLUSTER_TORQUE for dispatch of jobs in the nodes of a supercomputer |
| THREAD_POOL_SIZE | FOR LOCAL DISPATCHER ONLY. Thread pool size |
| GENERATOR_JAR_PATH | FOR CLUSTER_TORQUE DISPATCHER ONLY Path for the generator (e.g. Utilization Series Generator) jar file. In the supercomputer, that generator is executed as an independent jar program |
| CLUSTER_USER_EMAIL | FOR CLUSTER_TORQUE DISPATCHER ONLY User email |
| NUMBER_OF_CLUSTER_JOBS | FOR CLUSTER_TORQUE DISPATCHER ONLY Number of cluster jobs to be sent to the nodes |
| Property | Description |
|---|---|
| GENERATOR | Which generator to use. For now, Gen4MAST only implements UTILIZATION_SERIES, that generates systems in a series of increasing utilizations |
| CLEAN_AFTER | FOR UTILIZATION_SERIES GENERATOR ONLY. Boolean that indicates if intermediate files should be deleted once Gen4MAST finishes its execution |
| UTILIZATION_START | FOR UTILIZATION_SERIES GENERATOR ONLY. Initial system utilization in the series (percentage) |
| UTILIZATION_STEP | FOR UTILIZATION_SERIES GENERATOR ONLY. Step in the series of utilizations (percentage) |
| UTILIZATION_TOP | FOR UTILIZATION_SERIES GENERATOR ONLY. Final system utilization in the series (percentage) |
| Property | Description |
|---|---|
| STORER | Which results manager to use. For now Gen4MAST only implements SQLITE_MAST, which stores the results in an SQLite database. If CLUSTER_TORQUE dispatcher is used, a new database is created for each cluster job dispatched. |
| RESULTS_LOCATION | FOR SQLITE_MAST RESULTS MANAGER ONLY. Path of the results database |