Re: Intel P6 vs P7 system call performance

H. Peter Anvin
2002-12-17T21:34:20Z

Benjamin LaHaise wrote:
> On Tue, Dec 17, 2002 at 11:11:19AM -0800, H. Peter Anvin wrote:
>
>>>against 0xfffffxxx and "rollback" (or complete) any incomplete
>>>gettimeofday call prior to saving a task's state. but i bet that test is
>>>undesirable on all interrupt paths.
>>>
>>
>>Exactly. This is a real problem.
>
>
> No, just take the number of context switches before and after the attempt
> to read the time of day.
>

How do you do that from userspace, atomically? A counter in the shared
page?

-hpa