[info-mcl] digitool (MCL) / clozure (OpenMCL)

[Lawrence E. Bakst]

At 10:26 AM +0300 10/11/07, Toomas Altosaar wrote:
> >  > 4. I would like to see the compiler improved. In particular, I would
>>>  like to see math be faster, especially floating point math.
>>
>>I would like to second these requests - being able to do reasonably
>>fast floating point math on data allocated in a static region would be
>>quite useful for graphics applications in general.
>
>And for any vector/matrix-based digital signal processing as well.
>Currently in MCL we make calls to external frameworks written in C
>with XCode. We need guarantees that memory isn't moved while the call
>to C is in progress since C writes back directly to the addresses of
>the vector(s) supplied in the FFI call.
>
>If it is technically gc-wise feasible, some macro that would inhibit
>memory from being moved for the object in question:
>
>(with-gc-inhibited (vector1 vector2 vector3)
>   (some-FFI-op vector1 vector2 vector3))

I don't think this would be the correct long term approach. Turning the GC off is like tuning interrupts off inside an OS kernel. You really try not to do that. It's bad for performance and it effects other threads in bad ways. It doesn't scale. There are other reasons as well.

>If not, then being able to allocate the vectors in static regions
>would be the next best thing.

This is the correct approach in my opinion. I am not sure this shouldn't be the default for floating point vectors. You can still GC these heaps you just can't compact them or move the objects.

leb

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