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Date: Mon, 9 Feb 2009 15:23:43 -0800 (PST)
From: Davide Libenzi <davidel@xmailserver.org>
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To: Michael Kerrisk <mtk.manpages@gmail.com>
cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Thomas Gleixner <tglx@linutronix.de>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [patch 2/2] timerfd extend clockid support
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On Tue, 10 Feb 2009, Michael Kerrisk wrote:

> On Tue, Feb 10, 2009 at 9:10 AM, Davide Libenzi <davidel@xmailserver.org> wrote:
> > On Tue, 10 Feb 2009, Michael Kerrisk wrote:
> >
> >> > and I did not have even the time to peek
> >> > into the core timer code to see if the usage of other timer types in
> >> > eventfd would create problems. That's why I asked Thomas if they'd behave
> >> > differently from an hrtimer caller POV.
> >> > I'll try to take a look by myself today or tomorrow.
> >>
> >> Okay -- hopefully my test program may be useful (even if it is not
> >> itself fully tested yet, it's patterned after a similar test program I
> >> wrote fot the POSIX timers API, so it should mostly work).
> >
> > Answer was pretty easy once you look at the code :)
> > Timerfd uses core hrtimer functions, and clockids different from the ones
> > timerfd already handles, fall into the CPU-timers domain. Domain that is
> > not handled by hrtimer.
> > Changes to timerfd to support CPU-based timers are really deep (more than
> > changes, is a total rewrite). not only to timerfd, but also to CPU-based
> > timers to deliver notification by means different than signals.
> > Given the amount of code change, and given that a posix-timers->signalfd
> > bridge could solve the problem, I'm not going even close to suggest such a
> > change.
> 
> Davide,
> 
> Will you nevertheless push the patch that adds the EINVAL flags checks?

Sure, I'll send it to Greg and Andrew.


- Davide