linux-kernel - Any hardware timers avialable to user-space?

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Message-ID: <AANLkTimJ+g=VuvW0HeGKX1my4JY+nWkBbRhP9nCFeawd@mail.gmail.com>
Date:	Fri, 7 Jan 2011 14:51:08 -0600
From:	Paul Sheer <paulsheer@...il.com>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Any hardware timers avialable to user-space?

Hi there,

I'm looking for a way to return the value of any hardware clock to user-space:

Dan Bernstein's 'clockspeed' (http://cr.yp.to/clockspeed.html) package
relies on the Pentium RDTSC instruction on Linux or gethrtime() on Solaris.
On Solaris, gethrtime() is the same as clock_gettime(CLOCK_MONOTONIC,...)

On Linux clock_gettime(CLOCK_MONOTONIC,...) incurs adjustments
(so sayeth lkml archives) and doesn't seem suitable for implementing
the kind of "ntp" client that is clockspeed's purpose.

Mentioned in Documentation/kvm/timekeeping.txt are a number of PC
hardware clocks like the 82C54.

Are any of these available to user space?

Are there any plans to create a gethrtime() function like on Solaris?

Has anyone suggested a new clock_gettime(CLOCK_HARDWARE,...) system call?

Many thanks

-paul
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