kicad-developers team mailing list archive

[Bernhard Stegmaier <stegmaier@xxxxxxxxxxxxx>]

OK, I’ll play around some more with GCD.

I’ll also check what a custom toolchain/compiler would mean.

We can decide then which way to finally go when more parallelisation stuff might be added in future.


Bernhard

> On 1. Mar 2018, at 14:25, Wayne Stambaugh <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>>> 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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