Re: [RFC][PATCH] linux-2.5.59_getcycles_A0

[Andi Kleen]

On Fri, Feb 07, 2003 at 06:42:21PM -0800, john stultz wrote:
> > of applications who just need an increasing time stamp in user space,
> > and who do not want to fight ntpd for this. One example for such 
> > an application is the X server who needs this for its internal 
> > event sequencing.
> > 
> > Implementing it based on the current time infrastructure is very easy -
> > you just do not add xtime and wall jiffies in, but only jiffies.
> 
> Actually, we can't do this, because if interrupts are being blocked
> jiffies won't change. That is why I'm trying to provide hardware clock
> access to hangcheck. It just so happened it was using get_cycles() as an
> interface and it seemed appropriate for moving to timer_ops.

monotonic clock can use the hw clock too. It just shouldn't use anything 
manipulated by settimeofday() et.al.

> 
> > I don't think doing any special hacks and complicating get_cycles()
> > for it is the right way. Just implement a new monotonic clock primitive
> > (and eventually export it to user space too) 
> 
> Ok, so you're telling me to use another interface. I'm down with that
> (sometimes I just need it spelled out). Name suggestions? 
> read_hw_timer?

monotonic_clock() 

-Andi