[Cffi-devel] Fw: Help perfecting my GC finalizer/constructor

[Joeish W]

Some new exciting information...I ran the create-mat function a million times and my memory went up a slight bit,  I ran a million more and it went up a gain..I ran a million more and it actually leveled off. After running a million more times it actually started going down.  I was able to see the Lisp GC at work...It doesn't seem to kick in until memory becomes an issue, again sir ...it was an honor


On Saturday, April 26, 2014 4:24 AM, Willem Rein Oudshoorn <woudshoo at xs4all.nl> wrote:
 
Joeish W <joeish80829 at yahoo.com> writes:
>
>
>> (defcfun ("cv_create_Mat" create-mat) (%cv-mat :garbage-collect t))
>>
>> a million times to bench mark it it was actually 4 times slower than
>> my original code....I really do need this all to be fast code, since
>> computer vision  can benefit from the speed.  Also I noticed when I
>> ran the (create-mat) function 1,000,000
 times my ram went up a tiny
>> bit and didn't go down..Is that normal for finalizers.
>
>Well, that it is a bit slower is not really surprising because:
>
>1. CLOS classes are instantatied to wrap the pointer 
>2. The trivial garbage needs to keep track of the objects
>3. The conversion code is done by generic functions.
>
>However, this is solvable.  But I really would not focus on this right
>now.  I cannot really imagine that creating the matrix is the
>bottleneck.  
>
>With respect to the memory, as long as it does not grow indefinitely I
>would not worry about it.  The trivial garbage package might introduce
>some memory overhead which is not directly reclaimed by the garbage
>collector.  
>
>
>> When I use
>> with-* macros or manual MM I don't get an increase in ram on my
>> system.  I would like to include finalizers in my library but is there
>> any way to
 overcome these obstacles to make that happen...Again the
>> time you took to help me on this is much appreciated. :)You really
>> helped me to understand.
>
>Using `with-*` macros is a good idea.  Inside these macros you can
>do the manual garbage collection and avoid maybe the generic type
>conversion.    But to make it robust the `with-*` macros will not (I
>expect) be faster than the code you have now.  
>
>Making the code fast is certainly doable and not hard, but you should
>first make it work and figure what needs to be fast and which
>conveniences you are willing to give up for the speed improvement.
>
>Wim Oudshoorn
>
>
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