My spinlock obviously has a busy-spin loop whilst the lock fails to be acquired:

while(try_lock() == false)
{
    // Use _mm_pause() or _tpause() here?
}

I noticed I don’t have _mm_pause() inside the loop. I understand omitting this can cause performance degradation regarding memory barriers/fences/ordering?

Before adding _mm_pause() I discovered _tpause():

https://www.felixcloutier.com/x86/tpause

However, from the Intel Intrinsics Guide it usage seems slightly more complicated.

I would like to maximize performance/not concerned with power consumption.

Which should I use and if it’s _t_pause(), how is it used correctly? I cannot find any example usage, even on Github.

Architecture will be 2022+ Intel Xeon models.

EDIT:

I’ve just noticed _mm_pause() latency is 140 cycles?! I can’t see a figure for _tpause() though.