Re: [PATCH] pmtmr and PRINTK_TIME timings display

[Borislav Petkov]

On Tuesday 16 August 2005 00:18, john stultz wrote:
> On Thu, 2005-08-04 at 17:23 +0200, Borislav Petkov wrote:
> > I get it. Actually, I wasn't very sure whether this is the right solution
> > since my desktop machine uses tsc timer as default while the laptop the
> > pmtmr. I also remember that there was a patch a while ago on lkml which
> > enabled a modifiable behavior for PRINTK_TIME through a /proc interface
> > and kernel boot option but it somehow didn't get accepted. Ok, then,
> > since we keep the jiffies solution across arch's, how can I force the
> > kernel to use tsc for printk timings so that i can see the deltas between
> > the different printk's instead of the jiffies_64 ns value? The Pentium-M
> > Centrino on the laptop evidently supports rdtsc as a msr instruction.
>
> The issue is that there are a number of laptops that do not properly
> support cpufreq and additionally newer laptop chips halt their TSC's
> when they go into C3 mode. This keeps the TSC from working as a proper
> timesource on these systems, and causes the need for alternative
> timesources like the ACPI PM timer.

This _is_ actually my laptop I'm testing it on and sofar no problem. But as 
Steven pointed out earlier, one probably needs a different kind of timing 
information besides delta timings. Besides, <scripts/show_delta> can do all 
the formatting and delta computation already.

Thanks & regards,
Borislav Petkov.
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