When did High-Resolution Timers hit mainline?

["Michael Kerrisk" <mtk.manpages@googlemail.com>]

Hi Ingo, Thomas,

I want to update some timer and sleep man pages to reflect the arrival
of high-resolution timers.  However, it's not quite clear to me when
HRTs properly arrived in mainline.  Was it 2.6.21?  And at that point,
was the resolution for all timer and sleep calls based on HRTs, so
that they all became more accurate?  (Or was it the case that various
system calls switched over to HRTs in different later kernel
versions?)  Specifically, I'm thinking of the following system calls

nanosleep()
clock_nanosleep()
setitimer()
timer_create()/timer_settime()

Was it the case that pre 2.6.21 (or whatever) these were all
jiffy-based in their accuracy, and then post 2.6.21, they were all HRT
based (if CONFIG_HIGH_RES_TIMERS is enabled)?

Cheers,

Michael
-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
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