Re: Intel P6 vs P7 system call performance

[H. Peter Anvin]

Pavel Machek wrote:
>>
>>don't many of the multi-CPU problems with tsc go away because you've got a
>>per-cpu physical page for the vsyscall?
>>
>>i.e. per-cpu tsc epoch and scaling can be set on that page.
> 
> Problem is that cpu's can randomly drift +/- 100 clocks or so... Not
> nice at all.
> 

­­±100 clocks is what... ±50 ns these days?  You can't get that kind of
accuracy for anything outside the CPU core anyway...

	-hpa