Re: [ANNOUNCE] ktimers subsystem
From: Christopher Friesen
Date: Mon Sep 19 2005 - 23:58:06 EST
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
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