Re: What is timo from sleep(9) functions

From: Warner Losh <>
Date: Thu, 05 May 2022 14:38:21 UTC
On Thu, May 5, 2022 at 7:50 AM Farhan Khan <> wrote:

> Hi all,
> Hopefully simple question:
> What is the unit of the `int timeo` parameter in sleep(9)? Is it the
> timeout in milliseconds? Or would 1 mean a second?
> Related, what does the `hz` variable mean and why is it used? I see
> instances of timo's in multiples of hz (ie, hz * 10). OpenGrok shows it
> defined in a few different places and its not clear to me which it is.

The units are ticks. 1/hz seconds. There's other functions that let you
sleep with other units (all the _sbt ones).

     The parameter timo specifies a timeout for the sleep.  If timo is not
     then the thread will sleep for at most timo / hz seconds.  If the
     expires, then the sleep function will return EWOULDBLOCK.