Discussion Mediatek SoC thread

[DZero]

Ahem...

The maximum amount of L2 cache the Cortex A725 can be configured with is 1 MB.

Even Dimensity 9400 only has a total of 7 MB of L2 private caches across it's 8 cores.

Is 1 MB per core or per cluster? If is per core, it fits since the A725 on the big cores only uses 1 MB and on the "small ones" just 512 kb.
If is per cluster, well, time to use the L3 cache then.

 

[FlameTail]

Is 1 MB per core or per cluster? If is per core, it fits since the A725 on the big cores only uses 1 MB and on the "small ones" just 512 kb.
If is per cluster, well, time to use the L3 cache then.

ARM cores cannot be put in a cluster with shared L2.

That's why Apple/Qualcomm's CPU is special.

 

[MS_AT]

ARM cores cannot be put in a cluster with shared L2.

That's why Apple/Qualcomm's CPU is special.

Not sure about the newest ones but AMD/Xilinx is using a72s and a53s in its FPGA SoCs with shared L2 as LLC

 

[DZero]

ARM cores cannot be put in a cluster with shared L2.

That's why Apple/Qualcomm's CPU is special.

So, is per core no? If that so, that is what I mean. I should added "total" in the part, but the idea is the same mentioned previously.

 

[Nothingness]

Not sure about the newest ones but AMD/Xilinx is using a72s and a53s in its FPGA SoCs with shared L2 as LLC

Are you sure of that? The private (but coherent) L2 is mandatory IIRC.

 

[MS_AT]

Are you sure of that? The private (but coherent) L2 is mandatory IIRC.

https://docs.amd.com/r/en-US/ug1085-zynq-ultrascale-trm/Arm-v8-Architecture hopefully the link points to the correct place. https://docs.amd.com/viewer/attachment/dqE2tE0k~iMhpEDoQwXIKg/DH_fGSDkzyH4lTKZ0NNiBg

The Cortex-A53 MPCore processor’s L2 memory system size is 1 MB. It contains the L2 cache pipeline and all logic required to maintain memory coherence between the cores of the cluster.

Anyway there are up to 4 cores in the cluster. Unless there is something that evades me, I think it is fair to say the cores in the cluster share the L2 cache.

AMD/Xilinx Versal should be similar but with A72 cores. Versal Gen2 is using A78 cores and indeed has L2 private caches and then L3.

 

[Nothingness]

https://docs.amd.com/r/en-US/ug1085-zynq-ultrascale-trm/Arm-v8-Architecture hopefully the link points to the correct place. https://docs.amd.com/viewer/attachment/dqE2tE0k~iMhpEDoQwXIKg/DH_fGSDkzyH4lTKZ0NNiBg

Anyway there are up to 4 cores in the cluster. Unless there is something that evades me, I think it is fair to say the cores in the cluster share the L2 cache.

AMD/Xilinx Versal should be similar but with A72 cores. Versal Gen2 is using A78 cores and indeed has L2 private caches and then L3.

Sorry I wasn't clear: I was talking about A72 not A53.

 

[MS_AT]

Sorry I wasn't clear: I was talking about A72 not A53.

https://docs.amd.com/r/en-US/am011-versal-acap-trm/Features?tocId=gx43DWsCtVGZ6t6wLtyJ6A here is a link to Versal with A72, I think the block diagrams and general description are suggesting identical layout with respect to L2 as in case of Ultrascale [A53].