Faster Dlang Execution

Jun 08, 2021

seany

Jun 08, 2021

Basile B.

Jun 08, 2021

Jack

Jun 08, 2021

H. S. Teoh

Jun 08, 2021

seany

Jun 08, 2021

June 08, 2021

Re: Faster Dlang Execution

Posted by Basile B.
in reply to seany

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Basile B.

Posted in reply to seany

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On Tuesday, 8 June 2021 at 17:10:47 UTC, seany wrote:

Hello

How can I increase the speed of executable files created via :

dub build -b release

try dub build -b release --compiler=ldc2

Then you can set some specific DFlags for ldc, like -O3 or --mcpu

I am unable to parallellise all of it, as it depends on part of the result being calculated before something else can be calculated.

I have many nonsafe, nonpure functions.

nothrow presumably opens optimisation opportunities with the stack management, although it's not verified

Classes are virtual by defalut.

set them final when possible. When not possible set the virtual methods that
are not overridden final.

Profiling doesn't help, because different input is causing different parts of the program to become slow.

if you're on linux, you can try callgrind + kcachegrind instead of builtin intrumentation.

Thank you.

On Tue, Jun 08, 2021 at 05:10:47PM +0000, seany via Digitalmars-d-learn wrote: [...] > Profiling doesn't help, because different input is causing different parts of the program to become slow. [...] Do you have any more specific information about what kind of inputs cause which parts of the program to slow down? Without more details it's hard to say what the problem is. But I'd say, if you care about performance you should fix *all* of the slow parts that your profiler finds. There are some performance best practices that you should follow, such as reduce frequent GC allocations, avoid expensive algorithms (like O(n^2) or worse) where possible, avoid excessive copying of data, perform I/O in larger blocks instead of small bits at a time, avoid excessive indirection (final methods where they don't need to be virtual, by-value types instead of deep dereferencing, etc.), cache frequently-computed results, etc.. But more importantly, if you can elaborate a bit more on what your program is trying to do, it would help us give more specific recommendations. There may be domain-specific optimizations that you could apply as well. T -- MS Windows: 64-bit rehash of 32-bit extensions and a graphical shell for a 16-bit patch to an 8-bit operating system originally coded for a 4-bit microprocessor, written by a 2-bit company that can't stand 1-bit of competition.

On Tuesday, 8 June 2021 at 18:03:32 UTC, H. S. Teoh wrote:

But more importantly, if you can elaborate a bit more on what your program is trying to do, it would help us give more specific recommendations. There may be domain-specific optimizations that you could apply as well.

The program is trying to categorize GPS tracks.
It has to identify track that count as (somewhat) parallel (this is difficult to define) .

So I draw lines through points that have at most 5 m (as measured by vicenty -'s formula) RMS error from the trend line. Then i look for lines that can be considered "turn lines" ( a turn joining two parallel lines).

Then I draw a best fit boundary around it. I lay a square grid, and remove the squares where no line can be found.

Then I use this algorithm :
https://stackoverflow.com/questions/50885339/polygon-from-a-grid-of-squares

This runs at O(N²) for sure.

Does this help?

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