kicad-developers team mailing list archive

[Carl Poirier <carl.poirier.2@xxxxxxxxx>]

I think that we will have a very great speedup if each thread can have its
own Triangulation. Just by parallelizing the loop in RN_DATA::recalculate()
but going sequentially with one Triangulation, I still have ~25% gain in
calculation time.

On Wed, Jan 22, 2014 at 2:59 PM, Maciej Sumiński <maciej.suminski@xxxxxxx>wrote:

> Hi Carl,
>
> Thank you for putting efforts to boost the performance of the ratsnest.
> The function is brought by an external library (http://www.sintef.no/
> Projectweb/Geometry-Toolkits/TTL/), I am not sure what is exactly inside.
> The expected output should be a Delaunay triangulation of all nodes that
> are taken into account while computing ratsnest.
> The only issue I am aware of, is the function does not handle well empty
> containers, but it should not be the case right now.
>
> Now, when I looked again to the source code, RN_DATA is derived after
> hed::Node class (include/ttl/halfedge/hetriang.h), which contains a
> static field. Another thing is (I believe this is the main source of
> troubles) static hed::Triangulation (include/ttl/halfedge/hetraits.h:73).
> Sorry that I did not say about that before, but I have just discovered
> that it is done that way. I will try to change it, but unfortunately there
> are little chances that I manage to do that before Sunday.
>
> Regards,
> Orson
>
>
>
> On 01/22/2014 06:08 PM, Carl Poirier wrote:
>
>> Maciej,
>>
>> Can you summarize to me how the function "Triangulation::createDelaunay(
>> nodes.begin(), nodes.end() )" works, and what are the data structures
>> involved?
>>
>> I believe there are some dependencies in there.
>>
>>
>> On Tue, Jan 21, 2014 at 4:05 PM, Cirilo Bernardo
>> <cirilo_bernardo@xxxxxxxxx <mailto:cirilo_bernardo@xxxxxxxxx>> wrote:
>>
>>      >________________________________
>>      > From: Carl Poirier <carl.poirier.2@xxxxxxxxx
>>     <mailto:carl.poirier.2@xxxxxxxxx>>
>>      >To: Marco Serantoni <marco.serantoni@xxxxxxxxx
>>     <mailto:marco.serantoni@xxxxxxxxx>>
>>      >Cc: Kicad Developers <kicad-developers@xxxxxxxxxxxxxxxxxxx
>>     <mailto:kicad-developers@xxxxxxxxxxxxxxxxxxx>>
>>
>>      >Sent: Wednesday, January 22, 2014 3:51 AM
>>      >Subject: Re: [Kicad-developers] Net names and net codes
>>      >
>>      >
>>      >
>>      >There are some things in the code that don't like being
>>     multithreaded. If I parallelize the for loop in
>>     RN_DATA::Recalculate( int aNet ), I get a segfault. It does not
>>     happen if I put a lock to the call updateNet( i ), but obviously
>>     there is no increase in performance. I'm trying to find out what's
>>     the problem now.
>>      >
>>      >
>>      >
>>     This sounds to me like data is being altered by different threads
>>     and possibly there is some memory reallocation happening (growing
>>     arrays, etc). Locks are only needed when there is contention
>>     somewhere and of course locks should only be held for as short as
>>     needed. Another pitfall with threading is that some variables may
>>     need to be declared 'volatile' if they can be altered in another
>>     thread while one function is executing. For example, let's say the
>>     variable 'bool someX' can be altered in 2 threads; something like
>>     this can happen:
>>
>>     1. FunctionA starts, and runs a loop while(!someX) { ... }
>>     2. FunctionB sets 'someX' to 'true'
>>     3. FunctionA continues to run the loop, which is not the intended
>>     behavior
>>
>>     Of course similar things can happen when using shared memory and
>>     forked processes.
>>
>>     Threading has other problems to watch out for - for example, are
>>     there any static variables in functions? If so then you simply
>>     cannot thread those functions without locks.
>>
>>     - Cirilo
>>
>>
>>
>>
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>>
>