Re: Rob: Verne Tice's High Resolution Timing routines
Well how about using the normal timer interrupt counter and just using
the read time stamp instruction to interpolate between the timer
ticks, so the worst error would be less than a timer tick, and the
best outcome would increase the resolution of the timer.
Dan
On 12/18/05, Robert Craig <guest at rapideuphoria.com> wrote:
>
>
> posted by: Robert Craig <rds at RapidEuphoria.com>
>
> Vincent wrote:
> >
> > Great News: I found a "patch" solution to time()'s performance issues!
> > I feel so relieved now! 
> >
> > Not only does Verne's library offer a high resolution time(), but also =
out-performs
> > Euphoria v2.5 time() and is even faster than v1.2 on DOS and about 25% =
faster
> > on Windows. I made some minor optimizations (which sped up hrtime() eve=
n more),
> > and added memory deallocation routines to his library. I couldn't test =
it on
> > Linux or FreeBSD, but I imagine the performance would be much improved =
too.
> >
> > Not that you're is interested, but I thought I'd share the results. =
:
> >
> > Sequence operations:
> > * v1.2 'EX.exe' has slightly faster slicing than v2.5 'EX.exe' w/ hrtim=
e().
> > * v2.5 'EX.exe' w/ hrtime() performs 2x faster appending than v1.2 'EX.=
exe'.
> > * v2.5 'EX.exe' w/ hrtime() beats v1.2 'EX.exe' by a fair margin in all=
other
> > sequence tests.
> > * On Windows hrtime() is about 25% faster than regular time() on most b=
enchmarks,
> > but is still beaten slightly by v1.2 'EX.exe' in 3 out of 5 sequence te=
sts (it's
> > a close though, and the other 2 are faster).
> >
> > Old Sieve:
> > * v2.5 'EX.exe' w/ hrtime() is ~1.622x faster than normal v2.5 time().
> > * v2.5 'EX.exe' w/ hrtime() is about 5-10% faster than v1.2 time().
> > * v2.5 'EXW.exe' w/ hrtime() is the same speed as normal v2.5 time().
> >
> > New Sieve:
> > The newer sieve benchmark was designed better with very little reliance=
on time()
> > in determinding results. Both time() and hrtime() perform equally well =
on both DOS
> > & Windows; both of which are faster than v1.2 time().
> >
> >
> > The problem is the library uses the RDTSC CPU instruction, which is onl=
y available
> > in Pentium & K6 class CPUs and newer. So if you have a 386 or 486, your=
out
> > of luck and would have stick with normal time().
> >
> > Another problem is if the CPU has dynamic clock frequency adjustment te=
chnology
> > (speed-step, etc.), it would have to be disabled in the BIOS first; oth=
erwise
> > you could get unreliable timing results or worse.
> >
> > These issues will probably prevent you from ever implementing this sort=
of thing
> > in the official Euphoria interpreters, but you should still mention thi=
s library
> > in the time() comment paragraph, in the reference manual.
>
> I haven't looked at his stuff in any detail,
> but maybe there's a way of testing at start-up whether Verne's
> routines can be used. If not, I would fall back to using the
> normal time().
>
> Regards,
> Rob Craig
> Rapid Deployment Software
> http://www.RapidEuphoria.com
>
>
>
>
|
Not Categorized, Please Help
|
|
