lkml.org 
[lkml]   [2012]   [Jan]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [patch] x86, tsc: fix SMI induced variation in quick_pit_calibrate()
From
Date
On Mon, 2012-01-16 at 17:30 -0800, Linus Torvalds wrote:
> On Mon, Jan 16, 2012 at 4:52 PM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> >
> > Hmm. I get the feeling that we should remove that line entirely.
>
> Yeah, I really cannot come up with a single good reason to keep that
> line, and suspect that I was a bit loopy when I wrote it.
>
> So here's the suggested trivially updated patch. Does this work for people?

It does work. But it is taking almost 105 iterations or so to stabilize.
And if I boot the system in power-save mode (lowest p-state), it takes
almost 115 iterations to stabilize (close to the 25msec limit). This is
on the latest gen platform.

So I suspect we can either go back to 500ppm error tolerance:

if ((d1+d2) >= delta >> 10)
continue;

or increase the MAX_QUICK_PIT_MS bit more.

thanks,
suresh



\
 
 \ /
  Last update: 2012-01-17 05:03    [W:0.094 / U:0.736 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site