Re: PROBLEM: no cpu MHz in /proc/cpuinfo on 2.6.25.4-rt6

[Mark Hounschell]

Arjan van de Ven wrote:
> On Wed, 11 Jun 2008 16:37:38 -0400
>>> Mark 
>>>
>> Ok, what would one use besides the tsc to take a fast high-res time
>> stamp in a kernel module that could also be used in user land (same
>> time source) to for instance calculate  the the time between an event
>> in the kernel to an event in user land?
>>
>> do_gettimeofday / gettimeofday are not really acceptable.
> 
> 
> why not? both of these (they're teh same) are the best the kernel can
> do. If there was a better way to do it, gettimeofday() would use it.
> It's not even a system call if we can get away with it
> (although system calls are pretty cheap)
> 
> really, think about it. if there was a better way, gettimeofday() would
> use it.
> 
> 

The results of gettimeofday are worse that what you describe about the tsc.
NTP etc... and take considerably longer the a tsc read.

Mark
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