Messages in this thread | | | Date | Wed, 14 Jul 2004 13:28:39 -0700 (PDT) | From | Christoph Lameter <> | Subject | Re: gettimeofday nanoseconds patch (makes it possible for the posix-timer functions to return higher accuracy) |
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On Wed, 14 Jul 2004, john stultz wrote:
> Honestly, I'm not a fan of the patch. It realistically only helps ia64 > and and adds more confusing code to the generic time code. If there > isn't an real/immediate need for this, I'd wait to 2.7 for a better > cleanup.
The immediate need is that clock_gettime only returns microseconds scaled to nanoseconds.
> None the less, I do understand the desire for the change (and am working > to address it in 2.7), so could you at least use a better name then > gettimeofday()? Maybe get_ns_time() or something? Its just too similar > to do_gettimeofday and the syscall gettimeofday().
Right. I had it named getnstimeofday before but the feeling was that the patch should not introduce a new name. Any approach that would allow progress on the issue would be fine with me.
> Really, I feel the cleaner method is to fix do_gettimeofday() so it > returns a timespec and then convert it to a timeval in > sys_gettimeofday(). However this would add overhead to the syscall, so I > doubt folks would go for it.
do_gettimeofday is used all over the linux kernel for a variety of purposes and lots of code depends on the presence of a timeval struct.
> I think the ia64 time interpolation code is a step in the right > direction (def better then the i386 bits), but it still isn't the > cleanest and clearest way. My plan is to select a reliable timesource > for the system, then use a periodic interrupt to accumulate time from > the timesource (in order to avoid overflows). This avoids lost tick > issues and cleanly separates the timer subsystem from the time of day > subsystem.
That is what the changes to the time_interpolator do.
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