Question Zen 6 Speculation Thread

[Fjodor2001]

You can model it.

Now you’re begging.

 

[adroc_thurston]

Now you’re begging.

I wish, already did the boring math eons ago.
Now do the needful, kiddo.

 

[Fjodor2001]

I wish, already did the boring math eons ago.
Now do the needful, kiddo.

I already did it 2x eons ago.

 

[inquiss]

For MT and power constrained, better to have many cores at low frequency than few cores at high frequency. Optimal points on v/f curve and all that.

Depends how many cores....there are many more numbers for cores for typical socket power consumption where this isn't true than where it is true..

 

[StefanR5R]

Depends how many cores....there are many more numbers for cores for typical socket power consumption where this isn't true than where it is true..

Moar cores are only good as long as the workload scales (obviously), and as long as your fabric overhead stays in check...

Timed Linux Kernel Compilation 6.8, allmodconfig
Core Ultra 9 285K (24c/24t, TSMC 3nm) + DDR5-8000: 581 s • 227 W = 132 kJ
Core Ultra 9 285K (24c/24t, TSMC 3nm) + DDR5-6400: 587 s • 224 W = 132 kJ
Core Ultra 5 245K (14c/14t, TSMC 3nm): 932 s (source; haven't found power figures)
Ryzen 9 9950X (16c/32t, TSMC 4nm) + DDR5-6000: 586 s • 193 W = 113 kJ
Ryzen 9 9900X (12c/24t, TSMC 4nm) + DDR5-6000: 741 s • 158 W = 117 kJ
Ryzen 7 9700X (8c/16t, TSMC 4nm) + DDR5-6000: 1178 s • 87 W = 102 kJ

Timed Linux Kernel Compilation 6.8, defconfig
Core Ultra 9 285K (24c/24t, TSMC 3nm) + DDR5-8000: 48 s • 157 W = 7.5 kJ
Core Ultra 9 285K (24c/24t, TSMC 3nm) + DDR5-6400: 48 s • 156 W = 7.5 kJ
Core Ultra 5 245K (14c/14t, TSMC 3nm) + DDR5-8000: 75 s • 94 W = 7.0 kJ
Core Ultra 5 245K (14c/14t, TSMC 3nm) + DDR5-6400: 74 s • 93 W = 6.9 kJ
Ryzen 9 9950X (16c/32t, TSMC 4nm) + DDR5-6000: 47 s • 155 W = 7.3 kJ
Ryzen 9 9900X (12c/24t, TSMC 4nm) + DDR5-6000: 58 s • 132 W = 7.7 kJ
Ryzen 7 9700X (8c/16t, TSMC 4nm) + DDR5-6000: 88 s • 79 W = 7.0 kJ

In other words, parallelism has got a task energy price tag attached. Still, time is money, therefore it's alright to spend that extra energy in reasonably parallelizable jobs, like this example = code compilation of a bigger source base.

(PS: Fabric overhead should show up less in Olympic Ridge.)