kicad-developers team mailing list archive

[Tomasz Wlostowski <tomasz.wlostowski@xxxxxxx>]

On 01/03/18 14:29, Jon Evans wrote:
> It is also used for zone filling and in my new eeschema connectivity
> code that I'm hoping to get merged soon after V5 release.
> 
> I'm happy to help with research / testing of alternatives if we can't
> use OpenMP on Mac. 
> 
I'd like to hear from a *single* Apple user who designs boards of
sufficient complexity for the multithreading to really have an impact on
performance. What's next, rewriting Kicad in Objective-C?

- my 5 cents

Tom


> Jon
> 
> On Thu, Mar 1, 2018, 08:26 Wayne Stambaugh <stambaughw@xxxxxxxxx
> <mailto:stambaughw@xxxxxxxxx>> wrote:
> 
>     Ughh!  Thank you Apple.  I'm not opposed to this idea if OpenMP isn't a
>     viable option on macos.  I would like to see our macos port be on par
>     with linux and windows ports.
> 
>     Wayne
> 
>     On 3/1/2018 8:20 AM, Bernhard Stegmaier wrote:
>     > I did look around a bit.
>     > Looks like OpenMP isn’t a friend of Xcode clang, because Apple has its
>     > own Grand Central Dispatch (libdispatch) implementation/library doing
>     > similar things (at first glance, didn’t look into details).
>     > So, I guess OpenMP maybe won’t happen soon with stock toolchain or we
>     > would have to use non-stock toolchain (probably with all problems that
>     > come with that - I have seen bad things mixing compilers, etc.).
>     >
>     > Seems to be quite easy to convert OpenMP for loop parallelisation
>     to GCD:
>     > <<<
>     > //#pragma omp parallel for
>     > //for( signed int i = 0; i < aPolySet.OutlineCount(); ++i )
>     > dispatch_queue_t queue =
>     > dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
>     > dispatch_apply(aPolySet.OutlineCount(), queue, ^(size_t i)
>     > {
>     > ...
>     > }
>     > );
>     >>>>
>     >
>     > I just naively replaced all of the OpenMP for loops like above and now
>     > 3d-Viewer uses all cores.
>     > On my i7-3770T rendering time decreased from about 100s to 30s.
>     >
>     > I also did it for the ratsnest loop but didn’t notice any difference
>     > (maybe my test PCB was just to small).
>     >
>     > I could play around a bit to put that stuff into some nice syntax
>     maybe
>     > similar to what Microsoft has with concurrency::parallel_for_each
>     >   https://msdn.microsoft.com/en-us/library/dd492857.aspx
>     > So, at least ugly #ifdef around each parallel for loop could be
>     hidden.
>     >
>     > Don’t get me wrong, I don’t want to add just another parallelisation
>     > library/mechanism.
>     > And… I guess it won’t be possible to transparently cover all the
>     OpenMP
>     > pragma stuff maybe needed inside for loop body or maybe other stuff
>     > needed for GCD (e.g. when writing to variables outside for body).
>     >
>     > Thoughts? Would this be an option?
>     >
>     > Oh, yes:
>     > I did look into using STL std::async.
>     > Doesn’t seem to be a good idea, because it usually doesn’t seem to use
>     > anything like thread pools, etc. on various platforms.
>     > You probably don’t want to create that much threads… :) 
>     >
>     >
>     > Regards,
>     > Bernhard
>     >
>     >> On 1. Mar 2018, at 08:40, Bernhard Stegmaier
>     <stegmaier@xxxxxxxxxxxxx <mailto:stegmaier@xxxxxxxxxxxxx>
>     >> <mailto:stegmaier@xxxxxxxxxxxxx
>     <mailto:stegmaier@xxxxxxxxxxxxx>>> wrote:
>     >>
>     >> I had a quick look where OpenMP is used.
>     >>
>     >> I found it somewhere in the connectivity/ratsnest code.
>     >> I don’t know of any complaints in that area and even on my old HW I
>     >> had never a bad experience.
>     >>
>     >> And then, 3D-Viewer.
>     >>
>     >> So, in my opinion it is basically only about 3D-Viewer… I don’t know
>     >> if user experience will be that bad without OpenMP.
>     >> IMHO it’s only the Raytracing view, which isn’t intended to be used
>     >> for normal viewing stuff anyway.
>     >>
>     >> If I find some time over the weekend I will also try… but I don’t
>     >> think it will be worth it.
>     >>
>     >>
>     >> Regards,
>     >> Bernhard
>     >>
>     >>> On 1. Mar 2018, at 00:50, Jeff Young <jeff@xxxxxxxxx
>     <mailto:jeff@xxxxxxxxx>
>     >>> <mailto:jeff@xxxxxxxxx <mailto:jeff@xxxxxxxxx>>> wrote:
>     >>>
>     >>> Or rip it out and use STL?
>     >>>
>     >>>> On 28 Feb 2018, at 23:38, Jon Evans <jon@xxxxxxxxxxxxx
>     <mailto:jon@xxxxxxxxxxxxx>
>     >>>> <mailto:jon@xxxxxxxxxxxxx <mailto:jon@xxxxxxxxxxxxx>>> wrote:
>     >>>>
>     >>>> Hi all,
>     >>>>
>     >>>> Does anyone have a working build setup for getting OpenMP-enabled
>     >>>> KiCad out of MacOS?
>     >>>> If so, please share how -- I tried for a bit but couldn't get it
>     >>>> going (I'm not super familiar with the MacOS toolchain yet).
>     >>>>
>     >>>> We should make sure that the 5.0 release is built with OpenMP,
>     >>>> otherwise our Mac users are going to have a slower user experience.
>     >>>>
>     >>>> -Jon
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