def collect_metrics(env, strategy, servers_patched, servers_being_emptied,
migrations_data):
""" Gather metrics from the current maintenance step.
Supported metrics:
- Simulation steps
- Number of servers being updated
- Number of servers being emptied
- Number of updated servers
- Number of nonupdated servers
- Vulnerability Surface (Severo et al. 2020)
- Number of VM migrations
- Overall migrations duration (amount of time spent with migrations in the current step)
- Longer migration
- Shorter migration
- Average migration duration
- Servers occupation rate
- Servers consolidation rate
Parameters
==========
env : SimPy.Environment
Used to quantity the amount of simulation time spent by the migration
strategy : String
Name of the used maintenance strategy
servers_patched : List
List of servers updated in the current maintenance step
servers_being_emptied : List
List of servers being emptied in the current maintenance step
migrations_data : List
Information on each migration performed in the current maintenance step
Returns
=======
output : Dictionary
List of metrics collected during the current maintenance step
"""
output = {}
# Number of simulation steps
output['simulation_steps'] = env.now
# Name of the used maintenance strategy
output['strategy'] = strategy
# Other simulation metrics
output['metrics'] = {}
# Number of updated and nonupdated servers
output['metrics']['updated_servers'] = len(Server.updated())
output['metrics']['nonupdated_servers'] = len(Server.nonupdated())
# Vulnerability Surface (Severo et al. 2020) = Number of non-updated servers * Elapsed time
output['metrics']['vulnerability_surface'] = env.now * output['metrics'][
'nonupdated_servers']
# Gathering VM migration metrics
output['metrics']['vm_migrations'] = 0
output['metrics']['migrations_duration'] = 0
output['metrics']['longer_migration'] = 0
output['metrics']['shorter_migration'] = 0
output['metrics']['avg_migration_duration'] = 0
if len(migrations_data) > 0:
# Number of VM migrations performed in this interval
output['metrics']['vm_migrations'] = len(migrations_data)
# Time spent performing VM migrations
migrations_duration = sum(migr['duration'] for migr in migrations_data)
output['metrics']['migrations_duration'] = migrations_duration
# Longer migration
output['metrics']['longer_migration'] = max(
migr['duration'] for migr in migrations_data)
# Shorter migration
output['metrics']['shorter_migration'] = min(
migr['duration'] for migr in migrations_data)
# Average migration duration
output['metrics'][
'avg_migration_duration'] = migrations_duration / len(
migrations_data)
# Gathering server-related metrics
# Occupation rate
aggregated_occupation_rate = sum(sv.occupation_rate()
for sv in Server.all())
output['metrics']['occupation_rate'] = aggregated_occupation_rate / len(
Server.used_servers())
# Consolidation rate
output['metrics']['consolidation_rate'] = Server.consolidation_rate()
# Servers being updated
output['metrics']['servers_being_updated'] = len(servers_patched)
# Servers being emptied
output['metrics']['servers_being_emptied'] = len(servers_being_emptied)
return (output)
def show_metrics(dataset, heuristic, output_file=None):
""" Presents information and metrics of the performed placement
and optionally stores these results into an output CSV file.
Currently, this method outputs the following metrics:
- Servers occupation rate
- Servers consolidation rate
Parameters
==========
dataset : String
Name of the used dataset
heuristic : STring
Name of the used placement heuristic
output_file : String
Optional parameters regarding the name of the output CSV file
"""
# Servers occupation rate
occupation_rate = sum(sv.occupation_rate()
for sv in Server.all()) / len(Server.used_servers())
# Servers consolidation rate
consolidation_rate = Server.consolidation_rate()
# Prints out the placement metrics
print(
'========================\n== SIMULATION RESULTS ==\n========================'
)
print(f'Dataset: "{dataset}"')
print(f'Placement Strategy: {heuristic}\n')
print(f'Consolidation Rate: {consolidation_rate}')
print(f'Occupation Rate: {occupation_rate}\n')
print('Placement:')
for server in Server.all():
vms = [vm.id for vm in server.virtual_machines]
print(f'SV_{server.id}. VMs: {vms}')
# If the output_file parameter was provided, stores the placement results into a CSV file
if output_file:
with open(output_file, mode='w') as csv_file:
output_writer = csv.writer(csv_file,
delimiter='\t',
quotechar='"',
quoting=csv.QUOTE_MINIMAL)
# Creating header
output_writer.writerow([
'Dataset', 'Strategy', 'No. of Servers', 'No. of VMs',
'Occupation Rate', 'Consolidation Rate'
])
# Creating body
output_writer.writerow([
dataset, heuristic,
Server.count(),
VirtualMachine.count(), occupation_rate, consolidation_rate
])