Re: [ANNOUNCE] ktimers subsystem

Christoph Lameter
2005-09-19T23:05:28Z

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.

> > 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.