Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt

Martin J. Bligh
2005-07-13T21:33:58Z

>> Len Brown, a year ago: "The bottom line number to laptop users is
>> battery lifetime. Just today somebody complained to me that Windows
>> gets twice the battery life that Linux does."
>
> It seems the motivation for lower HZ is really:
>
> (1) ACPI/SMM suckage in laptops
>
> (2) NUMA systems with *horrible* remote memory latencies

It makes a difference on more normal SMP systems as well, just not as
much. See earlier in the thread. The NUMA system I used as an example
was actually a newer one with something like a 4:1 ratio, not an older
one with 20:1 or so. I have a feeling it's more to do with the number
of procs and the scheduler being invoked more than it is really to do
with NUMA ratios.

It seems people are agreed we want sub-HZ timers, and eventually go
to tickless ... the question is more what to do in the meantime.

M.