Re: [RFT] Port 0x80 I/O speed

From: Kyle McMartin
Date: Wed Dec 12 2007 - 00:23:19 EST


On Wed, Dec 12, 2007 at 12:31:18AM +0100, Rene Herman wrote:
> asm volatile ("rdtsc": "=A" (tsc));

rdtsc returns a 64-bit value in two 32-bit regs, you need to do

inline unsigned long long rdtsc(void)
{
unsigned int lo, hi;
asm volatile ("rdtsc": "=a" (lo), "=d" (hi));
return (unsigned long long)hi << 32 | lo;
}

as in msr.h, otherwise you'll only be looking at the value in %rax.

cheers,
Kyle
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