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share/man/man9/hardclock.9
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| .\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | .\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | ||||
| .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | .\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | ||||
| .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | .\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | ||||
| .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | .\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | ||||
| .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | .\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | ||||
| .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | ||||
| .\" POSSIBILITY OF SUCH DAMAGE. | .\" POSSIBILITY OF SUCH DAMAGE. | ||||
| .\" | .\" | ||||
| .Dd July 1, 2021 | .Dd February 27, 2023 | ||||
| .Dt HARDCLOCK 9 | .Dt HARDCLOCK 9 | ||||
| .Os | .Os | ||||
| .Sh NAME | .Sh NAME | ||||
| .Nm hardclock | .Nm hardclock | ||||
| .Nd real-time timer | .Nd real-time timer | ||||
| .Sh SYNOPSIS | .Sh SYNOPSIS | ||||
| .Ft void | .Ft void | ||||
| .Fn hardclock "int cnt" "int usermode" | .Fn hardclock "int cnt" "int usermode" | ||||
| .Sh DESCRIPTION | .Sh DESCRIPTION | ||||
| The | The | ||||
| .Fn hardclock | .Fn hardclock | ||||
| function is called periodically based on pending work. | function is called periodically based on pending work. | ||||
| The rate ranges from | The rate ranges from | ||||
| .Va hz | .Va hz | ||||
| times per second on a very busy system, to twice a second on an idle system. | times per second on a very busy system, to twice a second on an idle system. | ||||
| The | The | ||||
| .Va cnt | .Fa cnt | ||||
| argument reports an estimate of the number of ticks since the last call. | argument reports an estimate of the number of ticks since the last call. | ||||
| The sum of | Over long timescales, the average sum of | ||||
| .Va cnt | .Fa cnt | ||||
| over a second averages | over one second is | ||||
| .Va hz | .Va hz . | ||||
| over the long haul. | |||||
| See | See | ||||
| .Xr hz 9 | .Xr hz 9 | ||||
| for important details over shorter time scales. | for important details over shorter time scales. | ||||
| The argument | The | ||||
| .Va usermode | .Fa usermode | ||||
| is none-zero when | argument is non-zero when | ||||
| .Fn hardclock | .Fn hardclock | ||||
| is called from an context that interrupted usermode execution. | is called from an context that interrupted usermode execution. | ||||
| .Pp | .Pp | ||||
| .Fn hardclock | .Fn hardclock | ||||
| may perform different tasks such as: | may perform different tasks such as: | ||||
| .Bl -bullet -offset indent | .Bl -bullet -offset indent | ||||
| .It | .It | ||||
| Run the current process's virtual and profile time (decrease the | Run the current process's virtual and profile time (decrease the | ||||
| corresponding timers, if they are activated, and generate | corresponding timers, if they are activated, and generate | ||||
| .Li SIGVTALRM | .Li SIGVTALRM | ||||
| or | or | ||||
| .Li SIGPROF , | .Li SIGPROF , | ||||
| respectively). | respectively). | ||||
| .It | .It | ||||
| Increment the time-of-day, taking care of any | Increment the time-of-day, taking care of any | ||||
| .Xr ntpd 8 | .Xr ntpd 8 | ||||
| or | or | ||||
| .Xr adjtime 2 | .Xr adjtime 2 | ||||
| induced changes and leap seconds, as well as any necessary | induced changes and leap seconds, as well as any necessary | ||||
| compensations to keep in sync with PPS signals or external clocks, if | compensations to keep in sync with PPS signals or external clocks, if | ||||
| support for this is in the kernel (see | supported by the kernel. | ||||
| .Xr options 4 ) . | |||||
| .It | .It | ||||
| Schedule softclock interrupts ( | Schedule softclock interrupts | ||||
| .Xr swi 9 ) | .Po | ||||
| .Xr swi 9 | |||||
| .Pc | |||||
| processing. | processing. | ||||
| .It | .It | ||||
| Collect | Collect | ||||
| .Xr hwpmc 4 | .Xr hwpmc 4 | ||||
| statistics. | statistics. | ||||
| .It | .It | ||||
| Do device polling, when enabled. | Do device polling, when enabled | ||||
| .Po | |||||
| see | |||||
| .Xr polling 4 | |||||
| .Pc . | |||||
| .It | .It | ||||
| Implement software | Implement software | ||||
| .Xr watchdog 9 | .Xr watchdog 9 | ||||
| processing. | processing. | ||||
| .It | .It | ||||
| Enqueue | Enqueue | ||||
| .Xr epoch 9 | .Xr epoch 9 | ||||
| processing. | processing. | ||||
| .El | .El | ||||
| .Sh SEE ALSO | .Sh SEE ALSO | ||||
| .Xr adjtime 2 , | .Xr adjtime 2 , | ||||
| .Xr ntp_adjtime 2 , | .Xr ntp_adjtime 2 , | ||||
| .Xr signal 3 , | .Xr signal 3 , | ||||
| .Xr hwpmc 4 , | |||||
| .Xr polling 4 , | |||||
| .Xr ntpd 8 , | .Xr ntpd 8 , | ||||
| .Xr hz 9 | .Xr epoch 9 , | ||||
| .Xr eventtimers 9 , | |||||
| .Xr hz 9 , | |||||
| .Xr swi 9 , | |||||
| .Xr watchdog 9 | |||||