Re: [PATCH] time: Use CLOCK_REALTIME for time (BZ #30200)

[Florian Weimer <fweimer@redhat.com>]

* Adhemerval Zanella Netto:

> On 08/03/23 13:23, Bruno Haible wrote:
>> Paul Eggert wrote:
>>> My idea is to go through the apps I help maintain, and make sure that 
>>> they never call 'time' anywhere that it's important that a timestamp be 
>>> in sync with with the rest of the system
>> 
>> Alternatively, these applications can continue to call 'time', if the
>> package uses the Gnulib module 'time' that provides a workaround against
>> https://sourceware.org/bugzilla/show_bug.cgi?id=30200 .
>> 
>> Bruno
>
> Florian, do you really think that and latency increase of roughly 15ns 
> is really worth all the trouble gnulib is pushing? It means that we will 
> end up with programs that use CLOCK_REALTIME, while other use 
> CLOCK_REALTIME_COURSE.  
>
> If users really to squeeze more performance, they can use clock_gettime
> with CLOCK_REALTIME_COURSE.  It should have similar performance to
> time vDSO.

Eh, I think the difference derives from using the time vDSO entrypoint
(which your patch removed as well on x86-64).  I don't see a performance
difference between CLOCK_REALTIME and CLOCK_REALTIME_COARSE, so that's
not it.

Thanks,
Florian