Messages in this thread |  | | Date | Wed, 8 Nov 2017 20:07:27 +0100 | | From | Peter Zijlstra <> | | Subject | Re: [RFC PATCH v2] ftrace: support very early function tracing |
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On Wed, Nov 08, 2017 at 11:07:57AM -0500, Steven Rostedt wrote: > On Wed, 8 Nov 2017 09:10:58 +0100 > Peter Zijlstra <peterz@infradead.org> wrote: > > > On Tue, Nov 07, 2017 at 09:17:06PM -0500, Steven Rostedt wrote: > > > > +#ifdef CONFIG_X86_TSC > > > > + entry->clock = rdtsc(); > > > > +#else > > > > + entry->clock = trace_clock_local(); > > > > +#endif > > > > > > +#ifdef CONFIG_X86_TSC > > > > + cpu_khz = native_calibrate_cpu(); > > > > +#endif > > > > > > +#ifdef CONFIG_X86_TSC > > > > + ns = cycles_to_ns(entry->clock, cpu_khz); > > > > +#else > > > > + ns = entry->clock; > > > > +#endif > > > > Yeah, no, not going to happen... > > Agreed.
Depends on how early you need things; ideally you'd be able to use the stuff from here:
https://lkml.kernel.org/r/1504116205-355281-1-git-send-email-pasha.tatashin@oracle.com
That is, fix the normal time sources to work earlier instead of building parallel infrastructure.
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