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1.0 | Use Linux perf interface to collect data about performance events on a per core basis |
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2.0 | Use jevents library (PMU tools) | ||
3.0 | Report hardware cache events, kernel PMU events, software events, hardware specific events | ||
4.0 | Should have a configurable interval | ||
5.0 | Should have configurable hardware specific events list | ||
6.0 | Provide SNMP support for any collectd values, through an PMU MIB | ||
7.0 |
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Provide support for multi PMU uncore events |
Overview
Performance counters are CPU hardware registers that count hardware events such as instructions executed, cache-misses suffered, or branches mispredicted. They form a basis for profiling applications to trace dynamic control flow and identify hotspots. Linux perf interface provides rich generalized abstractions over hardware specific capabilities.
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- Resolving symbolic event names using downloaded event files
- Reading performance counters from ring 3 in C programs,
- Handling the perf ring buffer (for example to read memory addresses)
For more information on jevents see https://github.com/andikleen/pmu-tools/tree/master/jevents.
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The intel_pmu plugin collects information provided by Linux perf interface. Using this interface, the intel_pmu plugin should collect the following metrics:
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Name | Type | Type Instance | Description | |
| Kernel PMU events | ||||
cpu-cycles | counter | cpu-cycles |
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instructions | counter | instructions | ||
cache-references | counter | cache-references | ||
cache-misses | counter | cache-misses | ||
Branches | counter | Branches | ||
branch-misses | counter | branch-misses | ||
bus-cycles | counter | bus-cycles | ||
| Hardware cache events | ||||
L1-dcache-loads | counter | L1-dcache-loads | ||
L1-dcache-load-misses | counter | L1-dcache-load-misses | ||
L1-dcache-stores | counter | L1-dcache-stores |
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L1-dcache-store-misses | counter | L1-dcache-store-misses | ||
L1-dcache-prefetches | counter | L1-dcache-prefetches | ||
L1-dcache-prefetch-misses | counter | L1-dcache-prefetch-misses | ||
L1-icache-loads | counter | L1-icache-loads |
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L1-icache-load-misses | counter | L1-icache-load-misses | ||
L1-icache-prefetches | counter | L1-icache-prefetches |
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L1-icache-prefetch-misses | counter | L1-icache-prefetch-misses |
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LLC-loads | counter | LLC-loads |
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LLC-load-misses | counter | LLC-load-misses | ||
LLC-stores | counter | LLC-stores | ||
LLC-store-misses | counter | LLC-store-misses | ||
LLC-prefetches | counter | LLC-prefetches | ||
LLC-prefetch-misses | counter | LLC-prefetch-misses | ||
dTLB-loads | counter | dTLB-loads | ||
dTLB-load-misses | counter | dTLB-load-misses | ||
dTLB-stores | counter | dTLB-stores |
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dTLB-store-misses | counter | dTLB-store-misses | ||
dTLB-prefetches | counter | dTLB-prefetches | ||
dTLB-prefetch-misses | counter | dTLB-prefetch-misses | ||
iTLB-loads | counter | iTLB-loads |
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iTLB-load-misses | counter | iTLB-load-misses | ||
branch-loads | counter | branch-loads |
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branch-load-misses | counter | branch-load-misses |
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| Software events | ||||
cpu-clock | counter | cpu-clock | ||
task-clock | counter | task-clock | ||
context-switches | counter | context-switches | ||
cpu-migrations | counter | cpu-migrations |
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page-faults | counter | page-faults | ||
minor-faults | counter | minor-faults |
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major-faults | counter | major-faults | ||
alignment-faults | counter | alignment-faults | ||
emulation-faults | counter | emulation-faults |
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Plugin configuration
The following configuration options should be supported by intel_pmu collectd plugin:
Name | Description | Comment | |
Interval | The interval within which to retrieve statistics on monitored events in seconds | Interval option is supported by collectd and is defined in <LoadPlugin> block. No additional functionality should be developed in intel_pmu plugin to support this option. | |
ReportHardwareCacheEvents | Enable/disable monitoring of hardware cache events |
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ReportKernelPMUEvents | Enable/disable monitoring of kernel PMU events | ||
ReportSoftwareEvents | Enable/disable monitoring of software vents |
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| EventList | Path to hardware events list file for current CPU. | File can be downloaded by event_download.py script which is part of pmu-tools package. | |
HardwareEvents | String containing comma separated list of hardware specific events to monitor |
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| Cores | Core groups definition. Monitored metrics are reported only for configured cores. If this option is omitted all available cores are monitored. If a group is enclosed in square brackets each core is added individually to a separate group (that is statistics are not aggregated). | Allowed formats: |
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| DispatchMultiPmu | Enable/disable dispatching of cloned multi PMU for uncore events. If disabled only total sum is dispatched as single event. If enabled separate metric is dispatched for every counter. | If enabled information about event type is added to type_instance. |
Here is an example of the plugin configuration section of collectd.conf file:
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HWSpecificEvents "L2_RQSTS.CODE_RD_HIT,L2_RQSTS.CODE_RD_MISS" "L2_RQSTS.ALL_CODE_RD"
Cores ""
DispatchMultiPmu false
</Plugin>
Implementation details
intel_pmu plugin does not introduce its own layer of functionality. It just reads configuration provided by user and prepares all needed parameters/data structures for jevents API. This table shows the correspondence between plugin’s API and jevents API that is used to configure Linux perf monitoring.
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plugin API | jevents API | Description |
pmu_config | Parse events groups to monitor provided by user in collectd.conf | |
pmu_init | resolve_event_extra | Resolve hardware specific events names to perf events (perf_event_attr) |
| jevent_next_pmu | Expand event into multiple PMU if neccessary (in use for uncore events) | |
setup_event | Setup perf events for monitoring | |
pmu_read | read_all_events | Read values of all monitored events |
pmu_shutdown | | |
For more details on plugin API see collectd plugin implementation guide https://collectd.org/wiki/index.php/Plugin_architecture.
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The following table outlines possible impact(s) the deployment of this deliverable may have on the current system.
Ref | System Impact Description | Recommendation / Comments |
1 | Plugin can easily exceed the default limit of allowed file descriptors. |
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The following assumptions apply to the scope specified in this document.
Ref | Assumption | Status | |
1 |
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Key Exclusions
The following exclusions apply to the scope discussed in this document.
Ref | Exclusion | Status | ||
1 |
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Key Dependencies
The following table outlines the key dependencies associated with this deliverable.
Ref | Dependency | Status | ||
1 | libjevents | |||
2 | Net-SNMP | |||
3 |
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4 |
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