Re: [ANNOUNCE] ktimers subsystem

Thomas Gleixner
2005-09-19T23:12:15Z

On Mon, 2005-09-19 at 16:04 -0700, Christoph Lameter wrote:
> On Tue, 20 Sep 2005, Thomas Gleixner wrote:
>
> > Hmm. I don't understand the argument line completely.
> >
> > 1. The kernel has to provide ugly mechanisms because a lot of
> > applications implementations are doing the Wrong Thing ?
>
> Lets skip the "wrong thing"... Or are you saying that glibc and all the
> apps are all wrong?
>
> Applications call gettimeofday for a variety of reasons. One is because it
> is widely available over different platformsn and application want to
> schedule things, need timestamps etc etc.

Accepted. But I still doubt that the number of calls to gettimeofday is
in anyway justified. The question I'm asking if it is really worth a
long and epic discussion about a single add instruction ?

> > > Many platforms can execute gettimeofday
> > > without having to enter the kernel.
> >
> > Which ones ? How is this achieved with respect to all the time adjust,
> > correction... code ?
>
> IA64 f.e. has a special instruction that allows access to kernel user
> space without having to do a context switch.

Ok, was not aware of that and John kindly clarified this already.

tglx