Each gem5 experiment is wrapped inside a run object.
These run objects contain all of the information required to execute the gem5 experiments and can optionally be executed via the gem5art tasks library (or manually with the
run() function.). gem5Run interacts with the Artifact class of gem5art to ensure reproducibility of gem5 experiments and also stores the current gem5Run object and the output results in the database for later analysis.
SE and FS mode runs
Next are two methods (for SE (system-emulation) and FS (full-system) modes of gem5) from gem5Run class which give an idea of the required arguments from a user’s perspective to create a gem5Run object:
@classmethod def createSERun(cls, name: str, gem5_binary: str, run_script: str, outdir: str, gem5_artifact: Artifact, gem5_git_artifact: Artifact, run_script_git_artifact: Artifact, *params: str, timeout: int = 60*15) -> 'gem5Run': ....... @classmethod def createFSRun(cls, name: str, gem5_binary: str, run_script: str, outdir: str, gem5_artifact: Artifact, gem5_git_artifact: Artifact, run_script_git_artifact: Artifact, linux_binary: str, disk_image: str, linux_binary_artifact: Artifact, disk_image_artifact: Artifact, *params: str, timeout: int = 60*15) -> 'gem5Run': .......
For the user it is important to understand different arguments passed to run objects:
name: name of the run, can act as a tag to search the database to find the required runs (it is expected that user will use a unique name for different experiments)
gem5_binary: path to the actual gem5 binary to be used
run_script: path to the python run script that will be used with gem5 binary
outdir: path to the directory where gem5 results should be written
gem5_artifact: gem5 binary git artifact object
gem5_git_artifact: gem5 source git repo artifact object
run_script_git_artifact: run script artifact object
linux_binary(only full-system): path to the actual linux binary to be used (used by run script as well)
disk_image(only full-system): path to the actual disk image to be used (used by run script as well)
linux_binary_artifact(only full-system): linux binary artifact object
disk_image_artifact(only full-system): disk image artifact object
params: other params to be passed to the run script
timeout: longest time in seconds for which the current gem5 job is allowed to execute
The artifact parameters (
run_script_git_artifact) are used to ensure this is reproducible run.
Apart from the above mentioned parameters, gem5Run class also keeps track of other features of a gem5 run e.g., the start time, the end time, the current status of gem5 run, the kill reason (if the run is finished), etc.
While the user can write their own run script to use with gem5 (with any command line arguments), currently when a
gem5Run object is created for a full-system experiment using
createFSRun method, it is assumed that the path to the
disk_image is passed to the run script on the command line (as arguments of the
Running an experiment
gem5Run object has everything needed to run one gem5 execution.
Normally, this will be performed by using the gem5art tasks package.
However, it is also possible to manually execute a gem5 run.
run function executes the gem5 experiment.
It takes two optional parameters: a task associated with the run for bookkeeping and an optional directory to execute the run in.
run function executes the gem5 binary by using
This creates another process to execute gem5.
run function is blocking and does not return until the child process has completed.
While the child process is running, every 5 seconds the parent python process will update the status in the
info.json file is the serialized
gem5run object which contains all of the run information and the current status.
gem5Run objects have 7 possible status states.
These are currently simple strings stored in the
Created: The run has been created. This is set in the constructor when either
Begin run: When
run()is called, after the database is checked, we enter the
Failed artifact check for ...: The status is set to this when the artifact check fails.
Spawning: Next, just before
Popenis called, the run enters the
Running: Once the parent process begins spinning waiting for the child to finish, the run enters the
Finished: When the child finished with exit code
0, the run enters the
Failed: When the child finished with a non-zero exit code, the run enters the
Run Already in the Database
When starting a run with gem5art, it might complain that the run already exists in the database. Basically, before launching a gem5 job, gem5art checks if this run matches an existing run in the database. In order to uniquely identify a run, a single hash is made out of:
- the runscript
- the parameters passed to the runscript
- the artifacts of the run object which, for an SE run, include: gem5 binary artifact, gem5 source git artifact, run script (experiments repo) artifact. For an FS run, the list of artifacts also include linux binary artifact and disk image artifacts in addition to the artifacts of an SE run.
If this hash already exists in the database, gem5art will not launch a new job based on this run object as a run with same parameters would have already been executed. In case, user still wants to launch this job, the user will have to remove the existing run object from the database.
Searching the Database to find Runs
gem5art provides the utility
gem5art-getruns to search the database and retrieve runs.
Based on the parameters,
gem5art-getruns will dump the results into a file in the json format.
usage: gem5art-getruns [-h] [--fs-only] [--limit LIMIT] [--db-uri DB_URI] [-s SEARCH_NAME] filename Dump all runs from the database into a json file positional arguments: filename Output file name optional arguments: -h, --help show this help message and exit --fs-only Only output FS runs --limit LIMIT Limit of the number of runs to return. Default: all --db-uri DB_URI The database to connect to. Default mongodb://localhost:27017 -s SEARCH_NAME, --search_name SEARCH_NAME Query for the name field
Manually searching the database
Once you start running the experiments with gem5 and want to know the status of those runs, you can look at the gem5Run artifacts in the database.
For this purpose, gem5art provides a method
getRuns, which you can use as follows:
import gem5art.run from gem5art.artifact import getDBConnection db = getDBConnection() for i in gem5art.run.getRuns(db, fs_only=False, limit=100): print(i)
Searching the Database to find Runs with Specific Names
As discussed above, while creating a FS or SE mode Run object, the user has to pass a name field to recognize
a particular set of runs (or experiments).
We expect that the user will take care to use a name string which fully characterizes a set of experiments and can be thought of as a
For example, if we are running experiments to test linux kernel boot on gem5, we can use a name field
boot_tests_[month_year] (where month_year correspond to the month and year when the experiments were run).
Later on, the same name can be used to search for relevant gem5 runs in the database.
For this purpose, gem5art provides a method
getRunsByName, which can be used as follow:
import gem5art.run from gem5art.artifact import getDBConnection db = getDBConnection() for i in gem5art.run.getRunsByName(db, name='boot_tests_v1', fs_only=True, limit=100): print(i)