> In the worst case, two sdram clients accessing different pages of the same bank, may cause repeated closing and opening of the pages, harming the usable bandwidth you can achieve. Which pages belong to a bank depends on the physical address lines of the buffers used. We have found that it is pretty common for buffers to be allocated in pathologically bad ways.

> NUMA allows us to have more control over this. We can split our sdram, into, say, 8 NUMA regions, and configure the kernel to interleave the allocations between the regions. In addition the sdram controller allows the address bits used for segmenting the banks to be reconfigured (which we've exposed through eeprom config SDRAM_BANKLOW).

https://forums.raspberrypi.com/viewtopic.php?t=378276