Re: [patch 2/2] timerfd extend clockid support

From: Michael Kerrisk
Date: Mon Feb 09 2009 - 18:25:23 EST


On Tue, Feb 10, 2009 at 12:23 PM, Davide Libenzi
<davidel@xxxxxxxxxxxxxxx> wrote:
> On Tue, 10 Feb 2009, Michael Kerrisk wrote:
>
>> On Tue, Feb 10, 2009 at 9:10 AM, Davide Libenzi <davidel@xxxxxxxxxxxxxxx> 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.

Thanks! Please CC me.

Cheers,

Michael


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Michael Kerrisk
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