Re: [discuss] [PATCH 4/4 TRY#3] optimize and simplify get_cycles_sync()

From: Michael Matz
Date: Mon Mar 12 2007 - 09:30:23 EST


Hi Joerg,

On Mon, 12 Mar 2007, Joerg Roedel wrote:

> > >+#define RDTSCP ".byte 0x0f, 0x01, 0xf9"
> > >+ alternative_io_two("cpuid\nrdtsc",
> > >+ "rdtsc", X86_FEATURE_SYNC_RDTSC,
> > >+ ".byte 0x0f, 0x01, 0xf9", X86_FEATURE_RDTSCP,
> > >
> >
> > why not use the RDTSCP macro here?
>
> Does this macro exist?

Look carefully at your patch again, or at least the four quoted lines
above. You've added it yourself, in exactly the form you'd need in the
alternative_io_two() call :-)

> I couldn't found it in the current git tree. And the rdtscp macros in
> msr.h use the plain opcode too.


Ciao,
Michael.
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