1. Manuals
  2. Tumbleweed
  3. rt-tests
  4. oslat(8)

Scroll to navigation

OSLAT(8) System Manager's Manual OSLAT(8)

NAME

oslat - OS Latency Detector

SYNOPSIS

oslat [ -shvz ] [ -b bucket-size ] [ -B bias ] [ -c cpu-list ] [ -C cpu-main-thread ] [ -f rt-prio ] [ --json filename ] [ -m workload-mem ] [-t runtime ] [ -T trace-threshold ] [ -w workload ] [ -W bucket-width ]

DESCRIPTION

oslat is an open source userspace polling mode stress program to detect OS level latency. The program runs a busy loop with no or various workloads, collecting TSC information and measuring the time frequently during the process.

OPTIONS

Specify the number of the buckets (4-1024).
Add a bias to all the buckets using the estimated mininum.
Specify CPUs to run on. For example, '1,3,5,7-15'.
Specify which CPU the main thread runs on. Default is cpu0.
Using specific SCHED_FIFO priority (1-99). Otherwise use the default priority, normally it will be SCHED_OTHER.
Write final results into FILENAME, JSON formatted.
Size of the memory to use for the workload (e.g., 4K, 1M). Total memory usage will be this value multiplies 2*N, because there will be src/dst buffers for each thread, and N is the number of processors for testing.
Specify test duration, e.g., 60, 20m, 2H (m/M: minutes, h/H: hours, d/D: days). By default the unit is s/second.
Stop the test when threshold triggered (in USEC). At the meantime, print a marker in ftrace and stop ftrace too.
Specify a kind of workload, default is no workload. Options: "no", "memmove".
Use a single thread when measuring latency at preheat stage NOTE: please make sure the CPU frequency on all testing cores are locked before using this parmater. If you don't know how to lock the freq then please don't use this parameter.
Interval between buckets in nanoseconds

NOTE: Widths not a multiple of 1000 cause ns-precision output You are responsible for considering the impact of measurement overhead at the nanosecond scale.

Show the help message.
Show the version of the program.
Don't display buckets in the output histogram if all zeros.

AUTHOR

oslat was written by Peter Xu <peterx@redhat.com>.

August 17, 2020