Monitoring Binaries with Variorum

While the Variorum API allows for detailed critical path analysis of the power profile of user applications as well as for integration with system software such as Kokkos, Caliper, and Flux through code annotations, there are scenarios where such annotations are not possible. In order to support such scenarios, we provide the var_monitor tool, which can monitor a binary externally with Variorum in a vendor-neutral manner. This tool can monitor an application externally without requiring any code changes or annotations.

The variorum/src/var_monitor directory contains this tool, which is built along with the regular Variorum build. While a target executable is running, var_monitor collects time samples of power usage, power limits, energy, thermals, and other performance counters for all sockets in a node at a regular interval. By default, it collects basic node-level power information, such as CPU, memory, and GPU power, at 50ms intervals, which it reports in a CSV format. It also supports a verbose (-v) mode, where additional registers and sensors are sampled for the advanced user. The sampling rate is configurable with the -i option. As an example, the command below will sample the power usage while executing a sleep for 10 seconds in a vendor neutral manner:

$ var_monitor -a "sleep 10"

The resulting data is written to two files:


Here, hostname will change based on the node where the monitoring is occurring. The summary file contains global information such as execution time. The dat file contains the time sampled data, such as power, thermals, and performance counters in a column-delimited format. The output differs on each platform based on available counters.

var_monitor also supports profiling across multiple nodes with the help of resource manager commands (such as srun or jsrun) or MPI commands (such as mpirun). As shown in the example below, the user can specify the number of nodes through mpirun and utilize var_monitor with their application.

$ mpirun -np <num-nodes> ./var_monitor -a ./application

We also provide a set of simple plotting scripts for var_monitor, which are located in the src/var_monitor/scripts folder. The script can generate per-node as well as aggregated (across multiple nodes) graphs for the default version of var_monitor that provides node-level and CPU, GPU and memory data. This script works across all architectures that support Variorum’s JSON API for collecting power. Additionally, for IBM sensors data, which can be obtained with the var_monitor -v (verbose) option, we provide a post processing and R script for plots.

In addition to var_monitor that is vendor-neutral, for Intel systems only, we provide two other power capping tools, power_wrapper_static, and power_wrapper_dynamic that allow users to set a static (or dynamic) power cap and then monitor their binary application.

The example below will set a package-level power limit of 100W on each socket, and then sample the power usage while executing a sleep for 10 seconds:

$ power_wrapper_static -w 100 -a "sleep 10"

Similarly, the example below will set an initial package-level power limit of 100W on each socket, sample the power usage, and then dynamically adjust the power cap step-wise every 500ms while executing a sleep for 10 seconds:

$ power_wrapper_dynamic -w 100 -a "sleep 10"