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 <mailto: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/
<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>
<mailto:cirilo_bernardo@yahoo.__com
<mailto:cirilo_bernardo@xxxxxxxxx>>> wrote:
>__________________________________
> From: Carl Poirier <carl.poirier.2@xxxxxxxxx
<mailto:carl.poirier.2@xxxxxxxxx>
<mailto:carl.poirier.2@gmail.__com
<mailto:carl.poirier.2@xxxxxxxxx>>>
>To: Marco Serantoni <marco.serantoni@xxxxxxxxx
<mailto:marco.serantoni@xxxxxxxxx>
<mailto:marco.serantoni@gmail.__com
<mailto:marco.serantoni@xxxxxxxxx>>>
>Cc: Kicad Developers
<kicad-developers@lists.__launchpad.net
<mailto:kicad-developers@xxxxxxxxxxxxxxxxxxx>
<mailto:kicad-developers@__lists.launchpad.net
<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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