Messages in this thread | | | Date | Wed, 8 May 2013 08:44:19 +0200 | From | Ingo Molnar <> | Subject | Re: Fwd: [GIT PULL] timer changes for v3.10 |
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* Pavel Machek <pavel@ucw.cz> wrote:
> > Sorry. You seem to not like the merged change, but I guess I'm not > > quite sure what exactly your objection is here. > > I'm not exactly sure what my objections are. > > TSC was not designed for long-term precise timekeeping. [...]
The TSC is just a 64-bit counter that can be read very cheaply.
If the TSC is _implemented_ precisely in hardware and is kept in sync over CPUs then it's obviously fit for long-term precise timekeeping from that point on.
> [...] I guess it may work ok for short naps, [...]
Historically the TSC was not very precise nor kept in sync, but see the measurements from Feng Tang, it's very precise now on good hardware - and it's also a very cheap to read clocksource.
> [...] but some people suspend their machines for longer than that. Plus > I wonder how it will interfere with /etc/adjtime.
If it's precise then why should it interfere?
The history of the TSC being problematic can be ignored the moment CPU makers fix it completely - and apparently that is happening...
Thanks,
Ingo
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