On Mon, Mar 12, 2007 at 06:08:11PM +0200, Avi Kivity wrote:
> Joerg Roedel wrote:
> >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.
> >  
> 
> -ENOCOFFEE?  You defined the macro 3 lines above the .byte directive...

Yes, lack of coffee, and even worse -EBLINDHACKER :-(

-- 
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to