Re: rdtscp instruction

[Christoph Egger <Christoph_Egger%gmx.de@localhost>]

On 02.08.10 23:06, David Laight wrote:
> On Mon, Jul 26, 2010 at 11:46:02AM +0200, Christoph Egger wrote:
>>
>> When we fill in the cpu id in MSR_TSC_AUX then userland
>> can detect and deal with TSC clock skews between different
>> physical cpus.
> 
> Unlikely since there can be a process switch between the msr read
> and tsc read, and the 2nd can run on a different cpu.

No, this can't happen. That's the point of the rdtscp instruction.
On a side note: Userland can't read an MSR as rdmsr instruction
can only be used by the OS.

Christoph