RE: FW: [RFC] A more general timeout specification

[Roman Zippel <zippel@linux-m68k.org>]

Hi,

On Wed, 31 Aug 2005, Perez-Gonzalez, Inaky wrote:

> >Why is that needed in a _general_ timeout API? What exactly makes it so
> >useful for everyone and not just more complex for everyone?
> 
> Because if a system call gets a timeout specification it needs to
> verify its correctness first. Instead of doing that at the point
> where it goes to sleep, that could be deep in an atomic section,
> we provide a separate function [timeout_validate()] which is the
> one you mention, to do that.
> 
> Usefulness: (see the rationale in the patch), but in a nutshell;
> most POSIX timeout specs have to be absolute in CLOCK_REALTIME
> (eg: pthread_mutex_timed_lock()). Current kernel needs the timeout
> relative, so glibc calls the kernel/however gets the time, computes
> relative times and syscalls. Race conditions, overhead...etc. 
> 
> This mechanism supports both. That's why it is more general.

Your patch basically only mentions fusyn, why does it need multiple clock 
sources? Why is not sufficient to just add a relative/absolute version, 
which convert the time at entry to kernel time?

bye, Roman
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