K/N IOS - IntArray Performance Issue

Native
1

Hello Kotlin Friends,

I do have issues with the performance of Kotliin/Native IntArray access.
Here is the code:

   fun createGetSet() {

        val time = measureTime {
            for (i in 0..loopNumber) {
                val array = IntArray(arraySize) { index -> index }
                for (index in 0 until arraySize) {
                    val value = array[index]
                    array[index] = value * 2
                }
            }
        }
        println("[Int Array] CreateGetSet: ${time.inWholeMilliseconds} ms")
    }

With a loop number of 1000 and an arraySize of 500x500, the measured time is:

on JVM - [Int Array] CreateGetSet: 154 ms
on iOSX64 - [Int Array] CreateGetSet: 3385 ms

This seems to be related to bridging Kotlin Int with native primitive int.
Any ideas how to solve iOS PERFORMANCE ???

Thanks

2

You should probably pass resulting arrays somewhere or better, use JMH for measuring the performance in JVM. JVM performs a lot of optimizations while your code runs. It is possible this code is entirely removed after JVM notices it does really nothing.

3

Thanks broot,

But my actual concern is doing operation on array element. And these operation are low on iOS. JVM is ok for now.

4

I understand that the performance on iOS is what concerns you, but how do you know it is really slow? 250e6 operations is quite a lot, so maybe ~3s is actually fast.

One thing that may cause Kotlin array accesses slower than in languages like e.g. C are boundary checks. I don’t use Koltin/Native, so I may be wrong, but I guess it adds such checks.

5

I suspect that mapping Kotlin Int to iOS Int is the problem !!!
Maybe boxing - unboxing !