Re: [ANNOUNCE] ktimers subsystem

["Christopher Friesen" <cfriesen@nortel.com>]

Thomas Gleixner wrote:
> On Mon, 2005-09-19 at 16:39 -0600, Christopher Friesen wrote:
> 
>>Thomas Gleixner wrote:

>>>We should rather ask glibc people why gettimeofday() / clock_getttime()
>>>is called inside the library code all over the place for non obvious
>>>reasons.

>>--flight-recorder style logs

> If you want to implement such stuff efficiently you rely on rdtscll() on
> x86 or other monotonic easy accessible time souces and not on a
> permanent call to gettimeofday.

Not portable across architectures, and doesn't work across all smp/numa 
environments.  Also not easy to compare with other nodes on the network, 
whereas with ntp-synch'd nodes you can use gettimeofday() for quite 
accurate correlations.

> Please beware me of red herrings. If application developers code with
> respect to random OS worst case behaviour then they should not complain
> that OS N is having an additional add instruction in one of the pathes.

Actually I'm not complaining about additional add instructions.  I was 
just suggesting some reasons why apps might reasonably want to know the 
time frequently.

Chris