Date: Thu, 28 Feb 2008 16:07:25 -0500 From: Jung-uk Kim <jkim@FreeBSD.org> To: freebsd-x11@FreeBSD.org Cc: delphij@delphij.net, Thomas Mueller <tmueller@sysgo.com> Subject: Re: Xorg vs gettimeofday() and clock_gettime() Message-ID: <200802281607.30178.jkim@FreeBSD.org> In-Reply-To: <20080227103210.694787ec@tom.ulm.sysgo.com> References: <47C320DB.70004@delphij.net> <18371.11144.568407.26227@gromit.timing.com> <20080227103210.694787ec@tom.ulm.sysgo.com>
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On Wednesday 27 February 2008 04:32 am, Thomas Mueller wrote:
> On Mon, 25 Feb 2008 13:56:40 -0700, John Hein wrote:
> > Xin LI wrote at 12:11 -0800 on Feb 25, 2008:
> > > Shall we make some source-level change to Xorg (either
> > > upstream under ifdef FreeBSD or our own port, _FAST clocks are
> > > not available on some other operating systems) so that we can
> > > override the gettimeofday() direct calls and X_GETTIMEOFDAY's
> > > to use clock_gettime with a faster clock?
> >
> > Sounds good to me.
> > I vote for putting in a patch in the x11-servers/xorg-server port
> > so it gets some quick exposure and then feeding it back upstream
> > where it can be added on their schedule.
>
> FWIW, xorg already has support for clock_gettime(CLOCK_MONOTONIC)
> in xorg-server-1.4/os/utils.c:
>
> _X_EXPORT CARD32
> GetTimeInMillis(void)
> {
> struct timeval tv;
>
> #ifdef MONOTONIC_CLOCK
> struct timespec tp;
> if (clock_gettime(CLOCK_MONOTONIC, &tp) == 0)
> return (tp.tv_sec * 1000) + (tp.tv_nsec / 1000000L);
> #endif
>
> X_GETTIMEOFDAY(&tv);
> return(tv.tv_sec * 1000) + (tv.tv_usec / 1000);
> }
>
> Apparently the autoconf check for presence of CLOCK_MONOTONIC fails
> on FreeBSD:
>
> #define _POSIX_C_SOURCE 199309L
> #include <time.h>
>
> int main(int argc, char *argv[]) {
> struct timespec tp;
>
> if (clock_gettime(CLOCK_MONOTONIC, &tp) == 0)
> return 0;
> else
> return 1;
> }
>
> /usr/include/time.h:
> #if !defined(CLOCK_REALTIME) && __POSIX_VISIBLE >= 200112
> #define CLOCK_REALTIME 0
> [...]
> #define CLOCK_MONOTONIC 4
>
> Was CLOCK_MONOTONIC already defined for _POSIX_C_SOURCE 199309?
So this test was introduced in the following commit:
http://lists.freedesktop.org/archives/xorg-commit/2006-November/009390.html
Google found me this:
http://www.opengroup.org/austin/mailarchives/ag-review/msg00489.html
'The recently-approved 1003.1j-2000 adds CLOCK_MONOTONIC to the list.'
I think 1003.1b-1993 added clock_gettime(2) and configure.ac tests
bogus spec.
Jung-uk Kim
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