[foreign] Poor performance?

[Jorn Vernee]

FWIW, I ran the benchmarks with the linkToNative back-end (using 
-Djdk.internal.foreign.NativeInvoker.FASTPATH=direct), but it's still 2x 
slower than JNI:

Benchmark                                   Mode  Cnt     Score     
Error  Units
JmhGetSystemTimeSeconds.jni_javacpp         avgt   50   298.046 ▒  
15.744  ns/op
JmhGetSystemTimeSeconds.panama_prelayout    avgt   50   596.567 ▒  
20.570  ns/op

Of course, like Aleksey says: "The numbers [above] are just data. To 
gain reusable insights, you need to follow up on why the numbers are the 
way they are.". Unfortunately, I'm having some trouble getting the 
project to work with the Windows profiler :/ Was currently looking into 
that.

Cheers,
Jorn

Maurizio Cimadamore schreef op 2019-05-17 16:51:
> On 17/05/2019 11:26, Maurizio Cimadamore wrote:
>> thanks you for bringing this up, I saw this benchmark few days ago and 
>> I took a look at it. That benchmark is unfortunately hitting on a 
>> couple of (transitory!) pain points: (1) it is running on Windows, 
>> which lacks the optimizations available for MacOS and Linux 
>> (directInvoker). When the linkToNative effort will be completed, this 
>> discrepancy between platforms will go away. The second problem (2) is 
>> that the call is passing a big struct (e.g. bigger than 64 bits). Even 
>> on Linux and Mac, such a call would be unable to take advantage of the 
>> optimized invoker and would fall back to the so called 'universal 
>> invoker' which is slow.
> 
> Actually, my bad, the bench is passing pointer to structs, not structs
> by value - which I think should mean the 'foreign+linkToNative'
> experimental branch should be able to handle this. Would be nice to
> get some confirmation that this is indeed the case.
> 
> Maurizio