This patch adds the two POSIX clocks CLOCK_REALTIME_HR and
CLOCK_MONOTONIC_HR to the posix clocks & timers package.  A
small change is made in sched.h and the rest of the patch is
against .../kernel/posix_timers.c.

Concerns and on going work:

The kernel interface to the signal delivery code and it's
need for &regs causes the nanosleep and clock_nanosleep code
to be very messy.  The supplied interface works for the x86
platform and provides the hooks for other platforms to
connect (see .../include/asm-i386/signal.h for details), but
a much cleaner solution is desired.

This patch guards against overload by limiting the repeat
interval of timers to a fixed value (currently 0.5 ms).  A
suggested change, and one I am working on, is to not put the
timer back in the timer list until the user's signal handler
has completed processing the current expiry.  This requires
a call back from the signal completion code, again a
platform dependent thing, BUT it has the advantage of
automatically adjusting the interval to match the hardware,
the system overhead and the current load.  In all cases, the
standard says we need to account for the overruns, but by
not getting the timer interrupt code involved in useless
spinning, we just bump the overrun, saving a LOT of
overhead.

This patch fixes the high resolution timer resolution at 1
micro second.  Should this number be a CONFIG option?

I think it would be a "good thing"® to move the NTP stuff to
the jiffies clock.  This would allow the wall clock/ jiffies
clock difference to be a "fixed value" so that code that
needed this would not have to read two clocks.  Setting the
wall clock would then just be an adjustment to this "fixed
value".  It would also eliminate the problem of asking for a
wall clock offset and getting a jiffies clock offset.  This
issue is what causes the current 2.5.44 system to fail the
simple:

time sleep 60

test (any value less than 60 seconds violates the standard
in that it implies a timer expired early).

Patch is against 2.5.44-bk1

These patches as well as the POSIX clocks & timers patch are
available on the project site:
http://sourceforge.net/projects/high-res-timers/

The 3 parts to the high res timers are:
 core           The core kernel (i.e. platform independent)
changes
 i386           The high-res changes for the i386 (x86)
platform
*posixhr        The changes to the POSIX clocks & timers
patch to
use high-res timers

Please apply.
-- 
George Anzinger   george@mvista.com
High-res-timers: 
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rml