---
name: "fi_mon_sampler"
section: "1"
platform: "linux"
package: "libfabric"
version: "2.7.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/fi_mon_sampler"
---

# fi\_mon\_sampler(1)

Simple sampler for ofi\_hook\_monitor provider.

## NAME

fi\_mon\_sampler - Simple sampler for ofi\_hook\_monitor provider.

## SYNOPSIS

-

  ```
   fi_mon_sampler [OPTIONS] <target>      sample from file(s) at <target>
  ```

## DESCRIPTION

Extract data from the ofi\_hook\_monitor provider via communication files. \<target\> can either be one communication file or a folder of files. Data is exported based on -f \<format\> and either printed to stdout (only for single files), or stored per communication file at -o \<outpath\>. The sampler can watch the communication files for changes via the option -w \<msec\> for repeated sampling.

The name format of the output files is based on the ofi\_hook\_monitor provider and is as follows: \<ppid\>\_\<pid\>\_\<sequential id\>\_\<job id\>\_\<provider name\>. ppid and pid are taken from the perspective of the monitored application. In a batched environment running SLURM, job id is set to the SLURM job ID, otherwise it is set to 0.

## HOW TO RUN

Launch a libfabric application with FI\_HOOK=monitor to enable the ofi\_hook\_monitor provider. Adjust the monitor provider settings according to [fi\_hook(7)](/fi_hook/7.md).

Then launch the sampler via fi\_mon\_sampler -o \<output\> \<target\>. By default, the ofi\_hook\_monitor provider stores data at /dev/shm/ofi/\<uid\>/\<hostname\>.

The sampler will generate output files in the directory specified at \<output\>, one for each monitored provider.

## OPTIONS

- *-w \<msec\>*

  Watch files for changes, check every \<msec\> milliseconds.

- *-f \<format\>*

  Output format. Currently only supports CSV.

- *-o \<outpath\>*

  Output file path. Uses stdout if unset.

## USAGE EXAMPLES

Launch a libfabric application and enable the ofi\_hook\_monitor provider:

-

  ```
  FI_HOOK=monitor fi_pingpong [OPTIONS]
  ```

Launch another fi\_pingpong with the respective settings.

Finally, launch the sampler:

-

  ```
  fi_mon_sampler -o $HOME -w 1000 -f csv /dev/shm/ofi/$UID/$HOSTNAME
  ```

## OUTPUT

Output files will be generated in the folder specified at -o \<output\>.

In -f csv mode, this will contain a CSV file with data for all monitored libfabric functions. For each function, both the count and sum counters are exported, indicated by the column name suffix \_c and \_s respectively. In addition, each function is monitored for each data size bucket. Refer to [fi\_hook(7)](/fi_hook/7.md) for more details.

Example CSV output, first four columns, first three rows:

-

  ```
  mon_recv_0_64_c,mon_recv_0_64_s,mon_recv_64_512_c,mon_recv_64_512_s
  0,0,0,0
  22529,0,0,0
  113664,0,0,0
  ```

## SEE ALSO

[fi\_hook(7)](/fi_hook/7.md)

## AUTHORS

OpenFabrics.