From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Abderrahmane Benbachir <abderrahmane.benbachir@polymtl.ca>,
linux-kernel@vger.kernel.org, mingo@redhat.com,
mathieu.desnoyers@efficios.com,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [RFC PATCH v2] ftrace: support very early function tracing
Date: Wed, 8 Nov 2017 20:07:27 +0100 [thread overview]
Message-ID: <20171108190727.GL3326@worktop> (raw)
In-Reply-To: <20171108110757.5ef58e53@gandalf.local.home>
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.
next prev parent reply other threads:[~2017-11-08 19:07 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 23:44 [RFC PATCH v2] ftrace: support very early function tracing Abderrahmane Benbachir
2017-11-08 2:17 ` Steven Rostedt
2017-11-08 8:10 ` Peter Zijlstra
2017-11-08 16:07 ` Steven Rostedt
2017-11-08 19:07 ` Peter Zijlstra [this message]
2017-11-08 19:19 ` Steven Rostedt
2017-11-08 19:33 ` Peter Zijlstra
2017-11-08 15:56 ` Abderrahmane Benbachir
2017-11-08 18:44 ` Abderrahmane Benbachir
2017-11-08 19:09 ` Steven Rostedt
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