## Friday, May 7, 2010

### A Python on iPad benchmark

Now that my iPad is really mine, i.e., jailbroken, I installed Python on it and tried a large integer arithmetic benchmark. I'm curious because this will indicate something about the performance of fully porting Sage to the iPad (though of course Sage would use MPIR for large integers...).

First, on my 64-bit 2.6Ghz Intel Dunnington box (sage.math.washington.edu):
```>>> import resource
>>> def cputime(s=0): return sum(resource.getrusage(resource.RUSAGE_SELF)[:2])-s
...
>>> t=cputime()
>>> a=3**(10**6)
>>> cputime()-t
0.53000000000000003
>>> b=a*(a+1)
>>> cputime()-t
2.46
```

Next on my laptop, which is a top-end macbook air (64-bit intel core2 duo running 64-bit python 2.6.x):
```>>> t=cputime()
>>> a=3**(10**6)
>>> cputime()-t
0.64609700000000003
>>> b=a*(a+1)
>>> cputime()-t
3.1051849999999996
```

```>>> t=cputime()
>>> a=3**(10**6)
>>> cputime()-t
2.3500000000000014
>>> b=a*(a+1)
>>> cputime()-t
9.5899999999999963
```

Not bad!! Note that 32-bit versus 64-bit (and Python 2.5 versus 2.6) may be relevant, depending on how Python big integer arithmetic is implemented.

As a bonus, I have an older iPhone 3G (not 3Gs), where we get:

```>>> t=cputime()
>>> a=3**(10**6)
>>> cputime()-t
7.6699999999999999
>>> b=a*(a+1)
>>> cputime()-t
```

Wow, so the iPhone 3G at this benchmark is about TEN TIMES slower than the iPad. No wonder the iPad feels snappier.

Note that I view genuinely porting Sage to the iPad/iPhone as something that will only ever be available to people who jailbreak their devices. This is because Apple bans running any interpreter except Javascript on the iPhone. (Of course, I can always hope that Apple will get sued into opening up their app store...) For a person like me, a jailbroken iPad is dramatically superior to the standard iPad -- full multitasking, ssh access, Python, being able to easily change screen brightness, having full access to the filesystem, etc. Now if only I had Sage! (Of course, Sage usable on the iPad via the web, but sometimes I don't have reliable network access.)