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lo2s - Lightweight Node-level Performance Monitoring

lo2s is available as open source at https://github.com/tud-zih-energy/lo2s

lo2s creates parallel OTF2 traces with a focus on both application and system view. The traces can contain any of the following information:

  • From running threads
    • Calling context samples based on instruction overflows
    • The calling context samples are annotated with the disassembled assembler instruction string
    • The framepointer-based call-path for each calling context sample
    • Per-thread performance counter readings
    • Which thread was scheduled on which CPU at what time
  • From the system
    • Metrics from tracepoints (e.g. the selected C-state or P-state)
    • The node-level system tree (cpus (HW-threads), cores, packages)
    • CPU power measurements (x86_energy)
    • Microarchitecture specific metrics (x86_adapt, per package or per core)
    • Arbitrary metrics through plugins (Score-P compatible)

In general lo2s operates either in process monitoring or system monitoring mode.

With process monitoring, all information is grouped by each thread of a monitored process group - it shows you on which CPU is each monitored thread running. lo2s either acts as a prefix command to run the process (and also tracks its children), or lo2s attaches to a running process.

In the system monitoring mode, information is grouped by logical CPU - it shows you which thread was running on a given CPU. Metrics are also shown per CPU.

In both modes, system-level metrics (e.g. tracepoints), are always grouped by their respective system hardware component.