[isabelle-dev] Poly/ML x86_64_32 available for testing

Fabian Immler immler at in.tum.de
Tue Jan 22 22:00:16 CET 2019

On 1/22/2019 2:28 PM, Makarius wrote:
> On 22/01/2019 20:05, Fabian Immler wrote:
>> These numbers look quite extreme:
>> The slowdown in polyml-5.7.1-8 is about a factor of 2-3 (and not 30 as
>> it seems to be the case with polyml-test-0a6ebca445fc).
>> The following is isabelle/ab5a8a2519b0 afp/f49f0b0ead38 on lxcisa0:
>> ML_PLATFORM="x86-linux"
>> ML_OPTIONS="--minheap 2000 --maxheap 4000"
>> Finished HOL-ODE-Numerics (0:25:27 elapsed time, 1:07:49 cpu time,
>> factor 2.66)
>> Finished HOL-ODE-ARCH-COMP (0:18:01 elapsed time, 0:26:19 cpu time,
>> factor 1.46)
> Can you point to some smaller parts of these sessions, where the effect
> is visible? We can then use profiling to get an idea what actually
> happens in x86_64_32.
It should be the by (tactic ...) invocations, which ultimately run 
generated code as an oracle (the one defined via @{computation_check} 

The term that is being evaluated should be printed when declaring
(But it takes a lot of time to get there...)

I would have assumed that it is the heavy use of int computations that 
makes the difference, and it should be precisely the kind that is tested 
in the attached Float_Test.thy.

On my Windows-Laptop and on lxcisa0, however, I see the expected 
slowdown of about a factor of 2, but not more...

Could the issue be related to specific machines?
(I am testing HOL-ODE-ARCH-COMP with 
polyml-test-0a6ebca445fc/x86_64_32-linux right now, but that does take 
some time...)


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theory Float_Test

definition "logistic p r x =
  normfloat (float_round_down p (float_round_down p (r * x)) * (float_plus_down p 1 (-x)))"

primrec iter where
  "iter p r x 0 = x"
| "iter p r x (Suc n) = iter p r (logistic p r x) n"

definition "logistic_chaos i = iter 30 (Float 15 (-4)) (Float 1 (-1)) (nat_of_integer i)"

ML \<open>val logistic_chaos = @{code logistic_chaos}\<close>
ML \<open>logistic_chaos 1000000\<close>

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