rfc: high-resolution timer framework

[Alexander Shishkin <alexander.shishkin%teleca.com@localhost>]

Hi everybody,

This is to announce and request for comments on the so-called
high-resolution timer framework [1] that we came up with and want to share
and further improve.

High-resolution timers are implemented on top of posix timers interface
and are meant to provide userspace applications with timers as accurate
as 1ms. Current implementation adds separate CLOCK_HIGHRES timer type,
which might be moved in place of CLOCK_REALTIME code at some point.

The implementation comes in three patches for the convenience: first one
introduces the framework into kernel so that it extends timecounter
structure with an additional field which is either a pointer to a
structure with two high-resolution timer methods or NULL in case a
timecounter in not capable of this. Relevant timecounter drivers are
changed to set this field to NULL; two other patches introduce experimental
high-resolution timer drivers based upon lapic and omap general-purpose
timer.

[1] http://koowaldah.org/people/ash/netbsd/hrtim-patchset.tar.gz

Regards,
--
Alex