Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 21 Apr 2005 09:13:02 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [PATCH] Bad rounding in timeval_to_jiffies [was: Re: Odd Timer behavior in 2.6 vs 2.4 (1 extra tick)] |
| |
On Thu, 21 Apr 2005, Chris Friesen wrote: > > Does mainline have a high precision monotonic wallclock that is not > affected by time-of-day changes? Something like "nano/mico seconds > since boot"?
High precision? No. We do have "jiffies since boot". We don't actually expose it anywhere, although you _can_ get it's "standardized version", aka "centi-seconds per boot" from things like /proc/uptime.
(Not high-performance, but such an interface _could_ be. It's one of the few things we could trivially map into the "system call page", and have accessible to user space with just a simple read - faster even than the "fast gettimeofday" implementations).
The thing is, most people who want the time of day want a real time with some precision. Getting "approximate uptime" really really _really_ fast might be useful for some things, but I don't know how many.
Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| ![\](/images/icornerr.gif) |