Re: [RFC PATCH] x86:Use cpu_khz for loops_per_jiffy calculation

Alok Kataria
2008-06-09T17:55:28Z

On Mon, 2008-06-09 at 06:11 -0700, Ingo Molnar wrote:
> * Alok Kataria <akataria@vmware.com> wrote:
>
> > --- linux-2.6.orig/arch/x86/kernel/tsc_32.c 2008-05-27 12:28:16.000000000 -0700
> > +++ linux-2.6/arch/x86/kernel/tsc_32.c 2008-06-03 17:28:46.000000000 -0700
> > @@ -401,6 +401,7 @@
> > void __init tsc_init(void)
> > {
> > int cpu;
> > + u64 lpj;
> >
> > if (!cpu_has_tsc || tsc_disabled) {
> > /* Disable the TSC in case of !cpu_has_tsc */
> > @@ -421,6 +422,10 @@
> > return;
> > }
> >
> > + lpj = ((u64)cpu_khz * 1000);
> > + do_div(lpj, HZ);
> > + lpj_tsc = lpj;
>
> that wont work very well as lpj_tsc is not declared.

lpj_tsc is declared in include/linux/delay.h, and that declaration is
available in tsc_32.c

I compile tested against current git too and seems fine to me.

Also this patch is not to be applied to any tree yet, i will make a
different patch which calculates lpj_tsc from tsc_khz instead and use it
only for the boor processor.
There were some concerns from Arjan and Pavel regarding cpu frequency
being different on different cpus. I was waiting to hear back from them
before sending a new patch.

Let me know your comments on my questions/suggestions from the earlier
post
http://marc.info/?l=linux-kernel&m=121269125317375&w=2

Thanks,
Alok

>
> Ingo