By: Michael S (already5chosen.delete@this.yahoo.com), December 8, 2022 8:32 am
Room: Moderated Discussions
Etienne (etienne_lorrain.delete@this.yahoo.fr) on December 8, 2022 6:20 am wrote:
> Looks like my AMD Ryzen 9 7950x has a L3 cache bandwidth of 63.9 GB/s, my current DRAM DDR5
> has either 49.6 GB/s (Jedec) or 52.5 GB/s (AMD Expo) measured by memtest86 UEFI.
> It seems some companies are increasing DRAM bandwidth: 8Gbps DDR5.
>
> I assume latency to L3 cache is still probably better than latency to
> DRAM, but in simple terms, do we still need L3 cache in processors?
63.9 GB/s = 14.2 B/clock sounds low.
For Zen3 on 7/9 parts AMD claims 32B/clock read + 32B/clock write. For each CCD.
Supposedly, Zen4 is similar.
> Looks like my AMD Ryzen 9 7950x has a L3 cache bandwidth of 63.9 GB/s, my current DRAM DDR5
> has either 49.6 GB/s (Jedec) or 52.5 GB/s (AMD Expo) measured by memtest86 UEFI.
> It seems some companies are increasing DRAM bandwidth: 8Gbps DDR5.
>
> I assume latency to L3 cache is still probably better than latency to
> DRAM, but in simple terms, do we still need L3 cache in processors?
63.9 GB/s = 14.2 B/clock sounds low.
For Zen3 on 7/9 parts AMD claims 32B/clock read + 32B/clock write. For each CCD.
Supposedly, Zen4 is similar.
