Re: [ANNOUNCE] ktimers subsystem

Pavel Machek
2005-09-22T10:32:30Z

Hi!

> > Also the basic prerequisite for for high resolution timers is a fast and
> > simple access to clock_monotonic rather than to a backward corrected
> > clock_realtime representation.
>
> Yup that may be a reason to tolerate the add for realtime.
>
> > We should rather ask glibc people why gettimeofday() / clock_getttime()
> > is called inside the library code all over the place for non obvious
> > reasons.
>
> You can ask lots of application vendors the same question because its all
> over lots of user space code. The fact is that gettimeofday() /
> clock_gettime() efficiency is very critical to the performance of many
> applications on Linux. That is why the addtion of one add instruction may
> better be carefully considered. Many platforms can execute gettimeofday
> without having to enter the kernel.

Eh? One addition is going to be lost in noise compared to syscall overhead.
(For vsyscall, you may be closer to truth, but I doubt it. You could still gain
more than one addition by using some strange calling convention).

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