Re: [ANNOUNCE] ktimers subsystem

Ingo Molnar
2005-09-24T05:16:15Z

* Roman Zippel <zippel@linux-m68k.org> wrote:

> On Fri, 23 Sep 2005, Thomas Gleixner wrote:
>
> > The idea of ktimers is to use the requested time given by a timespec in
> > human time without any corrections, so we actually can avoid the above.
> >
> > Also doing time ordered insertion into a list introduces incompabilities
> > between 32/64 bit storage formats.
>
> Except that the (time) range of the list would be limited I don't really
> see a big difference.
> Anyway, the biggest cost is the conversion from/to the 64bit ns value
> [...]

Where do you get that notion from? Have you personally measured the
performance and code size impact of it? If yes, would you mind to share
the resulting data with us?

Our data is that the use of 64-bit nsec_t significantly reduces the size
of a representative piece of code (object size in bytes):

AMD64 I386 ARM PPC32 M68K
nsec_t_ops 226 284 252 428 206
timespec_ops 412 324 448 640 342

i.e. a ~40% size reduction when going to nsec_t on m68k, in that
particular function. Even larger, ~45% code size reduction on a true
64-bit platform.

Ingo