x86 vs AMD64 OCaml compiler performance

x86 vs AMD64 OCaml compiler performance

[Jon Harrop]

I just timed recompilation of my latest project to both byte code and native 
code on both 900MHz Athlon t-bird and 800MHz Athlon64. To my suprise, 
compilation to native code takes roughly the same amount of time on both 
computers but compilation to byte code is slightly faster (1m18 vs 1m40) on 
x86 but vastly faster (21s vs 1m50) on AMD64.

Any ideas why?

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
Technical Presentation Software
http://www.ffconsultancy.com/products/presenta

Re: [Caml-list] x86 vs AMD64 OCaml compiler performance

[Florian Hars]

Jon Harrop wrote:
> Any ideas why?

You have doublechecked that you always use either ocamlopt or ocamlopt.opt,
but not accidentally one for x86 and the other for amd64? This would explain 
the factor of approximately 5 you see...

Yours, Florian.

Re: [Caml-list] x86 vs AMD64 OCaml compiler performance

[Jon Harrop]

On Wednesday 06 July 2005 07:44, Florian Hars wrote:
> You have doublechecked that you always use either ocamlopt or ocamlopt.opt,
> but not accidentally one for x86 and the other for amd64? This would
> explain the factor of approximately 5 you see...

You are quite right - I think only ocamlc on the AMD64 had been compiled to 
native code because it is the only executable that "ldd" will run on.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
Technical Presentation Software
http://www.ffconsultancy.com/products/presenta

Re: [Caml-list] x86 vs AMD64 OCaml compiler performance

[Robert Roessler]

Jon Harrop wrote:

> I just timed recompilation of my latest project to both byte code and native 
> code on both 900MHz Athlon t-bird and 800MHz Athlon64. To my suprise, 
> compilation to native code takes roughly the same amount of time on both 
> computers but compilation to byte code is slightly faster (1m18 vs 1m40) on 
> x86 but vastly faster (21s vs 1m50) on AMD64.

Ummm... do you mean "1800MHz" or "1.8GHz" for the Athlon64? :)

Robert Roessler
roessler@rftp.com
http://www.rftp.com

Re: [Caml-list] x86 vs AMD64 OCaml compiler performance

[Jon Harrop]

On Wednesday 06 July 2005 18:16, you wrote:
> Jon Harrop wrote:
> > I just timed recompilation of my latest project to both byte code and
> > native code on both 900MHz Athlon t-bird and 800MHz Athlon64. To my
> > suprise, compilation to native code takes roughly the same amount of time
> > on both computers but compilation to byte code is slightly faster (1m18
> > vs 1m40) on x86 but vastly faster (21s vs 1m50) on AMD64.
>
> Ummm... do you mean "1800MHz" or "1.8GHz" for the Athlon64? :)

No, I got that bit right - 800MHz (downclocked for the muggy summer). Running 
at 1.8GHz it compiles in 9s but overheats and switches off after a few 
minutes, especially when the GPU is working like a Trojan.

With compilers compiled to native code I now get:

              ocamlc ocamlopt
800MHz AMD64     18s      24s
1.8GHz AMD64      9s      12s
900MHz Athlon    27s      34s

I'd have expected the compilers to be doing mostly tree manipulation so I was 
expecting the AMD64 to perform poorly, as the tree-intensive Set.union was 
the only benchmark where my AMD64 was slower in 64-bit mode than in 32-bit 
mode. In fact, the AMD64 is no slouch.

The vast majority of the time is spent compiling only a few of the source 
files. Four of them are autogenerated and just contain 300kB of data each, so 
it's no surprise those are slow. The other is my implementation of a scene 
graph. Although it is very elegant and actually works very well, many of the 
types are half a page long, so my guess is that the time is spent in the type 
system there.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
Technical Presentation Software
http://www.ffconsultancy.com/products/presenta

Re: [Caml-list] x86 vs AMD64 OCaml compiler performance

[Christopher Campbell]

Jon Harrop wrote:
> On Wednesday 06 July 2005 18:16, you wrote:
> 
>>Jon Harrop wrote:
>>
>>>I just timed recompilation of my latest project to both byte code and
>>>native code on both 900MHz Athlon t-bird and 800MHz Athlon64. To my
>>>suprise, compilation to native code takes roughly the same amount of time
>>>on both computers but compilation to byte code is slightly faster (1m18
>>>vs 1m40) on x86 but vastly faster (21s vs 1m50) on AMD64.
>>
>>Ummm... do you mean "1800MHz" or "1.8GHz" for the Athlon64? :)
> 
> 
> No, I got that bit right - 800MHz (downclocked for the muggy summer). Running 
> at 1.8GHz it compiles in 9s but overheats and switches off after a few 
> minutes, especially when the GPU is working like a Trojan.

You probably have, but I'll ask anyway.  Have you checked the heatsink 
is seated properly and the case has suitable airflow?  I have a Athlon64 
3200 (Winchester) with a 6600GT in a room with a combi boiler in the 
cupboard and it's always bloomin' hot in here but the system never 
crashes and dies.  Mind you, it has a smaller cache and I don't live in 
Cambridge (unfortunately I live in damp dreach Glasgow).