Re: performance issues with SIMD function
On Friday, 3 November 2023 at 15:11:31 UTC, Bogdan wrote: Can anyone help me to understand what I am missing? Your loop is likely dominated by sin() calls, And the rest of the loop isn't complicated enough to outperform the compiler. What you could do is use the intrinsics to implement a _mm_sin_ps that makes 4x sines at once, then you'll see an improvement at scale.
Re: performance issues with SIMD function
On Friday, 3 November 2023 at 15:32:08 UTC, Sergey wrote:
On Friday, 3 November 2023 at 15:11:31 UTC, Bogdan wrote:
Hi everyone,
I was playing around with the intel-intrinsics library, trying
to improve the speed of a simple area function. I could not
see any performance improvements from the non-SIMD
implementation. The SIMD version is a little bit slower even
with LDC2 and --o3. Can anyone help me to understand what I am
missing?
Thanks!
Bogdan
In your SIMD algorithm has not so many gain from using SIMD.
The length of the loop is the same.
Also probably compiler applying some optimizations in regular
versions, that doing almost the same.
I think it was from the way I was running the benchmark:
```d
auto begin = Clock.currTime;
foreach (i; 0..100_000) {
res1 = areaMeters(polygon);
}
writeln("No SIMD ", Clock.currTime - begin);
begin = Clock.currTime;
foreach (i; 0..100_000) {
res2 = areaMetersSimd2(polygon);
}
writeln("SIMD", Clock.currTime - begin);
```
gives me:
```
No SIMD 1 sec, 80 ms, 765 μs, and 1 hnsec
SIMD1 sec, 120 ms, 765 μs, and 1 hnsec
```
```d
auto begin = Clock.currTime;
res1 = areaMeters(polygon);
writeln("No SIMD ", Clock.currTime - begin);
begin = Clock.currTime;
res2 = areaMetersSimd2(polygon);
writeln("SIMD", Clock.currTime - begin);
```
gives me:
```
No SIMD 19 μs and 3 hnsecs
SIMD16 μs and 8 hnsecs
```
Re: performance issues with SIMD function
On Friday, 3 November 2023 at 15:11:31 UTC, Bogdan wrote: Hi everyone, I was playing around with the intel-intrinsics library, trying to improve the speed of a simple area function. I could not see any performance improvements from the non-SIMD implementation. The SIMD version is a little bit slower even with LDC2 and --o3. Can anyone help me to understand what I am missing? Thanks! Bogdan In your SIMD algorithm has not so many gain from using SIMD. The length of the loop is the same. Also probably compiler applying some optimizations in regular versions, that doing almost the same.
Re: performance issues with SIMD function
On Friday, 3 November 2023 at 15:17:43 UTC, Imperatorn wrote: On Friday, 3 November 2023 at 15:11:31 UTC, Bogdan wrote: Hi everyone, I was playing around with the intel-intrinsics library, trying to improve the speed of a simple area function. I could not see any performance improvements from the non-SIMD implementation. The SIMD version is a little bit slower even with LDC2 and --o3. Can anyone help me to understand what I am missing? [...] Did you try using std.vector or __vector first? Typo, I mean those in core.simd or ldc.simd
Re: performance issues with SIMD function
On Friday, 3 November 2023 at 15:11:31 UTC, Bogdan wrote: Hi everyone, I was playing around with the intel-intrinsics library, trying to improve the speed of a simple area function. I could not see any performance improvements from the non-SIMD implementation. The SIMD version is a little bit slower even with LDC2 and --o3. Can anyone help me to understand what I am missing? [...] Did you try using std.vector or __vector first?
