Define grammar for workload characterization¶
https://blueprints.launchpad.net/watcher/+spec/workload-characterization-grammar
Problem description¶
When applications are deployed in cloud, they compete for resources and it becomes a challenge for “cloud operators to ensure” and “tenants to get” desired performance and quality of service (QoS) for the workloads.
When we run several workloads in cloud, we need to characterize these workloads as input to watcher for profiling, fingerprinting, application QoS, placements and consolidation. Audit can refer to these grammars and implement QoS Strategy
Also, from a cloud infrastructure standpoint, these workload characteristics can also be used to gauge SLAs and decisions for killing or rebalancing workloads elsewhere.
An example of workload characterization is a weighted combination of CPU, Memory or any other resource attributes like High IOPs, Network latency etc.
Scope of this blueprint is -
A definition of a grammar for characterizing workload specific targeting at composite metrics for a VM.
A lightweight solution for parsing the defined grammar using the TOSCA-Parser library.
A solution for persisting the grammar for VMs leveraging VM metadata.
Use Cases¶
As an OpenStack administrator or user, I want to be able to create a TOSCA structured workload character. As an OpenStack administrator or user, I want to be able to build an optimization strategy using the defined workload character grammar.
Project Priority¶
Pike
Proposed change¶
Workload characterization is important for QoS to achieve performance goals and SLAs. Building optimization strategies or workload placement based on the defined workload character.
Defining a workload character
A workload character will constitute one or more Performance Units.
A Performance Unit will have a resource name (Example - vcpus, cpu_util, memory, memory.usage, disk.device.iops), Value (Number of CPU Cores, Memory in MB, Number of IOPs), Unit, an Operator (>, <, =), and Weight (priority ranging from -20 to 19 for highest and lowest priorities respectively). Weights are used to create a threshold to optimally run the workload.
Resource name and units should be in compliance with Nova and any strategy supported metric services.
Example of a performance unit:
vcpus = 2 Cores
cpu_util > 90 %
memory.usage > 2000 MB
disk.device.iops > 1500 counts/s
Examples of Workload Characters
cpu_bound_workload: (vcpus = 2 Cores OR cpu_util > 90)
big_data_workload = (memory.usage > 2000 MB AND disk.device.iops < 1500 counts/s)
Represent workload character using TOSCA
The above can be represented in a TOSCA structure
Example :
cpu_bound_workload =
watcher:
derived_from: tosca.nodes.Root
description: '{vcpus} or {cpu_util}'
properties:
vcpus:
required: true
weight: -20
type: integer
constraints:
- equal: 2
cpu_util:
required: true
weight: 19
type: integer
constraints:
- greater_than: 90
disk_io_workload=
watcher:
derived_from: tosca.nodes.Root
properties:
disk_iops:
required: true
weight: 5
type: integer
constraints:
- greater_than: 1200
Parse and validate workload grammar
Use TOSCA-Parser module to parse a TOSCA serialized workload grammar and validate it by applying values from telemetry or other metrics.
Snippet to parse a grammar -
from toscaparser.nodetemplate import NodeTemplate
custom_snippet = '''
watcher:
derived_from: tosca.nodes.Root
description: '{vcpus} or {cpu_util}'
properties:
vcpus:
required: true
weight: -20
type: integer
constraints:
- equal: 2
cpu_util:
required: true
weight: 19
type: integer
constraints:
- greater_than: 90
'''
custom_def = yamlparser.simple_parse(custom_snippet)
equation = custom_def['watcher']['description']
data = '''
server:
type: watcher
properties:
vcpus: 2
cpu_util: 89
'''
parsed_data = yamlparser.simple_parse(data)
nodetemplate = NodeTemplate('server', parsed_data, custom_def)
p_names = {}
for p in nodetemplate.get_properties_objects():
try:
p.validate()
p_names[p.name] = True
except:
p_names[p.name] = False
print(equation.format(**p_names))
Output -
True
Here is more examples and documentation - https://pypi.org/project/tosca-parser/0.7.0
Store Grammar in VM Metadata
The grammar should be added as VM Metadata. Watcher will then poll this data and make it available in the cluster data model for Audit and Strategy to refer. This metadata addition will be watcher specific and should have an identifiable key like “watcher-workload-grammar”.
Example to store grammar in VM Metadata -
{
"meta": {
"workload_character":
"watcher:
derived_from: tosca.nodes.Root
description: '{vcpus} or {cpu_util}'
properties:
vcpus:
required: true
weight: -20
type: integer
constraints:
- equal: 2
cpu_util:
required: true
weight: 19
type: integer
constraints:
- greater_than: 90"
}
}
curl -H 'Content-Type: application/json' -H "X-Auth-Token: token" -X PUT -d '{
"meta": {
"workload_character":
"watcher:
derived_from: tosca.nodes.Root
description: '{vcpus} or {cpu_util}'
properties:
vcpus:
required: true
weight: -20
type: integer
constraints:
- equal: 2
cpu_util:
required: true
weight: 19
type: integer
constraints:
- greater_than: 90"
}
}'
https://openstack_controller:8774/v2.1/tenant_id/servers/9b4daf23-c01c-44ad-a
f7-4c20a7b382d6/metadata/workload_character
Alternatives¶
No Alternatives
Data model impact¶
Modifications will be made to the cluster data model to read and store VM metadata in memory for strategies and audits to reference.
REST API impact¶
None.
Security impact¶
None.
Notifications impact¶
None.
Other end user impact¶
None.
Performance Impact¶
None.
Other deployer impact¶
None.
Developer impact¶
None.
Implementation¶
Assignee(s)¶
Intel and Walmart are working together on this blueprint.
Primary assignee:
Chris Spencer(chrisspencer) Prashanth Hari (hvprash) Susanne Balle (sballe)
Other contributors:
Work Items¶
Create module for parsing the grammar
Modify cluster data model to read VM Metadata and store in memory for strategies and audits to refer
Refactor the code to populate workload grammar from vm_metadata in cluster data model - Model Root - https://git.io/vXSbA - Nova cluster data model - https://git.io/vXS9N
Dependencies¶
None.
Testing¶
None.
Documentation Impact¶
None.
References¶
None.
