On Fri, Mar 09, 2007 at 08:10:03PM +0200, Avi Kivity wrote:
> Joerg Roedel wrote:
> >From: Joerg Roedel <[EMAIL PROTECTED]>
> >
> >This patch simplifies the get_cycles_sync() function by removing
> >the #ifdefs from it. Further it introduces an optimization for AMD
> >processors. There the RDTSCP instruction is used instead of CPUID;RDTSC
> >which is helpfull if the kernel runs as a KVM guest. Running as a guest
> >makes CPUID very expensive because it causes an intercept of the guest.
> >
> > +#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? I couldn't found it in the current git tree. And
the rdtscp macros in msr.h use the plain opcode too.
Regards,
Joerg
--
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG
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