Re: [PATCH] i386 No-Idle-Hz aka Dynamic-Ticks 5

Srivatsa Vaddagiri
2005-08-08T15:06:44Z

On Mon, Aug 08, 2005 at 12:38:23AM -0700, Tony Lindgren wrote:
> It should not matter when the PIT gets reprogrammed, as the system time is
> not updated from PIT timer. Jiffies are calculated from a second timer, such
> as ACPI PM timer or TSC.

I am more worried about timer latencies and its effects. Because of this skew
between when jiffy interrupt was originally supposed to happen and when it
will now happen, it can lead to, for example, scheduling latencies upto
1 jiffy (for HZ=100, that could hurt some apps?) Not to mention that
this will not play well with high-res-timers, but that is probably
not a concern now!

--

Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017