kicad-developers team mailing list archive

[Maciej Sumiński <maciej.suminski@xxxxxxx>]

On 04/04/2016 12:50 PM, jp charras wrote:
> Le 04/04/2016 01:28, Collin Anderson a écrit :
>> So, I used to be into game development, I was big on writing my own engines from scratch in C++.
>> This exact memory management problem is one encountered very frequently in such projects.  Any
>> game developer lives by this mantra when it comes to memory management: never fragment the heap.
>>
>>
>> The reduction in memory usage cannot justify the system-wide impacts of heap fragmentation and
>> memory manager overhead caused by frequent allocation and freeing of large blocks.  The #if 1 on
>> line 178 should always be a #if 0, in my opinion.  The comment says, 'there is no point in
>> holding a large amount of memory when there is no use for it."  Of course there is a use for it.
>> There just isn't a use for it right that instant, but if that much simultaneous memory was at one
>> point needed, then its safe to assume it will be needed again, so just hold on to it until then.
>> Yes, that is wasteful, but it is less wasteful than the system-wide performance toll that
>> significant heap fragmentation can cause.  The reduced memory usage is simply not worth the cost.
>> It is better to consume the additional memory.
>>
>> As for improving cached_container, believe it or not, I actually have a container class I wrote
>> years ago that I am rather proud of, it was designed to manage large terrain meshes (I was
>> writing my own ROAM terrain rendering engine) and I am going to play around and see if its
>> adaptable to KiCad.  And if it is, I'll see if it is helpful.  It might be I just THINK it is
>> good, but isn't :).  If I have anything useful to add or modify in that class though, I'll do a
>> branch.
>>
>> Thanks!
>>
>>
> 
> Thanks for your help.
> I fully agree with you.
> However I am not the guy who wrote the cached container code.
> 
> In rev 6661, I disable this deallocation/reallocation option (This change was suggested by Orson,
> the author of this code).
> It is not yet perfect.
> 
> I still have this issue when switching off/on the Opengl GAL, because there is still a
> deallocation/reallocation memory
> 
> It could be worth to see if your container class can help to fix this (very annoying and serious,
> because I ran out of memory on a PC with 4Gb of memory, with 256 Mbytes chunks only) issue.

@Collin
I am really interested in the results, any performance boost is very
welcome.

@Jean-Pierre
I have just disabled cached container reallocation on switching between
OpenGL GAL and legacy (rev 6662). It will free the allocated memory when
switching between Cairo and OpenGL, but I think it is reasonable. Please
let me know if it fixes the problem on your hardware.

Regards,
Orson

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