Re: Does 2.6.26 provide nanosecond time to the user?

Re: Does 2.6.26 provide nanosecond time to the user?

[Robert Hancock]

Reg Clemens wrote:
> Im confused.
> (sorry I havent been following the linux-kernel mailing list on this)
> 
> Does 2.6.26 use nanosecond time
>     (1) internally?
>     (2) provide it to the user?
> 
> I see no way to turn it on/off in xconfig.
> Yet I do see STA_NANO defined in sys/timex.h which is a good start.
> 
> and IF it provides it to the user, what do I use to get nanosecond time.
> My search with man -k for timespec turns up
>       sys_clock_getres
> and sys_clock_gettime
> 
> or possibly clock_getres and clock_gettime, the man pages use both,
> but NONE of these entry points seem to exist in my system.
> 
> Puzzled.

clock_gettime should exist. Old glibc version?

Does 2.6.26 provide nanosecond time to the user?

[Reg Clemens]

Im confused.
(sorry I havent been following the linux-kernel mailing list on this)

Does 2.6.26 use nanosecond time
    (1) internally?
    (2) provide it to the user?

I see no way to turn it on/off in xconfig.
Yet I do see STA_NANO defined in sys/timex.h which is a good start.

and IF it provides it to the user, what do I use to get nanosecond time.
My search with man -k for timespec turns up
      sys_clock_getres
and sys_clock_gettime

or possibly clock_getres and clock_gettime, the man pages use both,
but NONE of these entry points seem to exist in my system.

Puzzled.


-- 
                                        Reg.Clemens
                                        reg@dwf.com

Re: Does 2.6.26 provide nanosecond time to the user?

[Måns Rullgård]

Reg Clemens <reg@dwf.com> writes:

> Im confused.
> (sorry I havent been following the linux-kernel mailing list on this)
>
> Does 2.6.26 use nanosecond time
>     (1) internally?
>     (2) provide it to the user?
>
> I see no way to turn it on/off in xconfig.
> Yet I do see STA_NANO defined in sys/timex.h which is a good start.
>
> and IF it provides it to the user, what do I use to get nanosecond time.
> My search with man -k for timespec turns up
>       sys_clock_getres
> and sys_clock_gettime
>
> or possibly clock_getres and clock_gettime, the man pages use both,
> but NONE of these entry points seem to exist in my system.

You might need to link with -lrt to get those functions.

-- 
Måns Rullgård
mans@mansr.com

Re: Does 2.6.26 provide nanosecond time to the user?

[Reg Clemens]

> Reg Clemens <reg@dwf.com> writes:
> 
> > Im confused.
> > (sorry I havent been following the linux-kernel mailing list on this)
> >
> > Does 2.6.26 use nanosecond time
> >     (1) internally?
> >     (2) provide it to the user?
> >
> > I see no way to turn it on/off in xconfig.
> > Yet I do see STA_NANO defined in sys/timex.h which is a good start.
> >
> > and IF it provides it to the user, what do I use to get nanosecond time.
> > My search with man -k for timespec turns up
> >       sys_clock_getres
> > and sys_clock_gettime
> >
> > or possibly clock_getres and clock_gettime, the man pages use both,
> > but NONE of these entry points seem to exist in my system.
> 
> You might need to link with -lrt to get those functions.
> 
Thanks, -lrt works fine, that answers that part of the question, how about
the first question.

-- 
                                        Reg.Clemens
                                        reg@dwf.com

Re: Does 2.6.26 provide nanosecond time to the user?

[Christoph Lameter]

Reg Clemens wrote:

> Thanks, -lrt works fine, that answers that part of the question, how about
> the first question.

The kernels use a variety of clocks internally. If the clocks are capable of
nanosecond resolution then the results will be available via clock_gettime().

Re: Does 2.6.26 provide nanosecond time to the user?

[Chris Friesen]

Reg Clemens wrote:
> Im confused.
> (sorry I havent been following the linux-kernel mailing list on this)
> 
> Does 2.6.26 use nanosecond time
>     (1) internally?
>     (2) provide it to the user?

It's available to userspace via clock_gettime(), but whether it really 
is accurate to sub-microseconds will depend on the specific version of 
the kernel and hardware architecture being used.

Chris