There are some recent discussions on the freebsd-current list. The infrastructure is there to provide a common shared page for processes to mmap into the address space... but according to Kip's comment, libc support is not there yet:
http://lists.freebsd.org/pipermail/freebsd-current/2011-June/025191.html Also, the kernel needs to update the variable in that shared page on each clock interrupt (depending on the resolution I believe), and I think that needs to be added too. IMO, the time returned by gettimeofday does not need to be high precision. There are higher resolution time APIs on Linux and I believe the application programmers know when to use the slower but more accurate clock API. (At least in Grid Engine we only need a quick way of getting the current time, and we don't care if it is precise to the nanosecond range.) See Linux security issue & solution: http://lwn.net/Articles/446528/ See also the Google SoC idea: http://wiki.freebsd.org/IdeasPage#Timecounter_Performance_Improvements_.28GSoC.29 Rayson ================================= Grid Engine / Open Grid Scheduler http://gridscheduler.sourceforge.net On Tue, Sep 6, 2011 at 8:49 PM, Manish Vachharajani <mani...@lineratesystems.com> wrote: > I believe that Linux uses a less precise clock that scales better > across cores and is much faster than the precise clock FreeBSD uses > even on one core. I don't know POSIX and other standards well enough > to know if this is an acceptable solution on FreeBSD. However, there > are less precise clocks on FreeBSD that are considerably faster (i.e., > the _FAST variants). Someone with more expertise in these matters > needs to comment on whether a change to using a _FAST clock is > appropriate in libc. If it is acceptable, I think that it is easier > to just make time use the FAST clock instead of getting programmers to > change their programs. > > On Tue, Sep 6, 2011 at 6:41 PM, Eitan Adler <li...@eitanadler.com> wrote: >> On Tue, Sep 6, 2011 at 6:44 PM, Manish Vachharajani >> <mani...@lineratesystems.com> wrote: >>> Lots of libraries assume that time is fast because it >>> is fast under Linux. >> >> Silly question, but why can't we make it fast too? >> >> -- >> Eitan Adler >> > > Manish > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org" > -- Rayson ================================================== Open Grid Scheduler - The Official Open Source Grid Engine http://gridscheduler.sourceforge.net/ _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
