High Resolution Timer Support

This product enhances select timer-related system calls and APIs to provide a resolution finer than the default 10 millisecond resolution. It is part of the core OS.

Summary of Change

What’s New for Customers Migrating from HP-UX 11i v1 September 2005?

This product enhances select timer-related system calls and APIs to provide a resolution finer than the default 10 millisecond resolution.

The affected APIs are as follows:

timer_settime()
setitimer()
nanosleep()
sigtimedwait()
ualarm()
usleep()
pthread_cond_timedwait()
semtimedop()

This product is controlled by the tunable hires_timeout_enable.

What’s New for Customers Migrating from HP-UX 11i v2 June 2006?

See “What’s New for Customers Migrating from HP-UX 11i v1 September 2005?”

Impact

Many applications desire a finer resolution than the current clock tick resolution of 10 milliseconds for these APIs. To achieve this, the tunable hires_timeout_enable can be set to 1. This will modify system-wide behavior of the aforementioned APIs to give a finer resolution.

Compatibility

There are no known compatibility issues with prior releases and no difference in behavior across PA-RISC and Itanium®-based architectures. A new dynamic tunable hires_timeout_enable is provided to enable or disable the enhancement. By default, the enhancement is not enabled.

Performance

Turning on the tunable may lead to an increase in the number of timer-related interrupts. Turning off the tunable may lead to a decrease in the number of timer-related interrupts.

Documentation

For further information, see the hires_timeout_enable(5) manpage.

Obsolescence

Not applicable.