Re: [tip:timers/tracing] hrtimer: Add tracepoint for hrtimers

From: Ingo Molnar
Date: Tue Oct 13 2009 - 14:43:10 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Tue, 2009-10-13 at 15:26 +0200, Ingo Molnar wrote:
> > * Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> >
> > > On Tue, 2009-10-13 at 09:08 +0200, Ingo Molnar wrote:
> > > > * Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
> > > >
> > >
> > > > > (unsigned long long)(((ktime_t) { .tv64 = REC->expires }).tv64)
> > > > >
> > > > > Is not easy. It's basically implementing a C interpreter :-(
> > > >
> > > > Btw., what i suggested quite some time ago was that we should bind
> > > > tracepoints by emitting C source code stubs, which tools can then build
> > > > and link in, using gcc.
> > >
> > > Yeah, and I thought about that too. But that kills any chance of
> > > running the trace on one box (non x86) and reading it on another
> > > (x86). And that is one of my goals for this.
> >
> > Why does it kill that chance?
>
> Ah, I was thinking binary libraries from the trace points. But I
> missed you said C source code.
>
> But still, we need to build a way to convert big endian to little, as
> well as perhaps converting 32bit to 64 bit longs. As well as vice
> versa.

Exporting the print line as C in a convenient way does not in any way
make it more difficult to define endianness and bit size - we have to do
that anyway. It's largely orthogonal.

Ingo
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