kicad-developers team mailing list archive

[Bernhard Stegmaier <stegmaier@xxxxxxxxxxxxx>]

Currently, I fully agree with you.

The only spot right now where it has real impact is the raytracing 3d viewer.
And for me it is also only 3x faster with threading, so not that critical for some “offline” functionality.

But more and more OpenMP stuff might get added which maybe will make an impact in future.
This has caused much problems with the zone filling already…

So, from my point of view at least a clear strategy should be defined.


Bernhard

> On 1. Mar 2018, at 14:34, Tomasz Wlostowski <tomasz.wlostowski@xxxxxxx> wrote:
> 
> 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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