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

-b, --bucket-size=N
    Specify the number of the buckets (4-1024).

-B, --bias
    Add a bias to all the buckets using the estimated mininum.

-c, --cpu-list=CPULIST
    Specify CPUs to run on. For example, '1,3,5,7-15'.

-C, --cpu-main-thread=CORE
    Specify which CPU the main thread runs on. Default is cpu0.

-f, --rtprio=PRIORITY
    Using specific SCHED_FIFO priority (1-99). Otherwise use the default priority, normally it will be SCHED_OTHER.

--json=FILENAME
    Write final results into FILENAME, JSON formatted.

-m, --workload-mem=SIZE
    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.

-D, --duration=TIME
    Specify test duration, e.g., 60, 20m, 2H (m/M: minutes, h/H: hours, d/D: days). By default the unit is s/second.

-T, --trace-threshold=THRESHOLD
    Stop the test when threshold triggered (in USEC). At the meantime, print a marker in ftrace and stop ftrace too.

-w, --workload=WORKLOAD
    Specify a kind of workload, default is no workload. Options: "no", "memmove".

-s, --single-preheat
    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.

-W, --bucket-width
    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.

-h, --help
    Show the help message.

-v, --version
    Show the version of the program.

-z, --zero-omit
    Don't display buckets in the output histogram if all zeros.

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