Intel Xeon E-Cores for Next Gen Sierra Forest and More at Hot Chips 2023

Intel has a new efficient core (E-core) only architecture called Sierra Forest coming in 1H 2024. This is a huge deal as it will allow Intel to compete for sockets in the cloud-native compute segment. At Hot Chips 2023, Intel outlined the new Sierra Glen E-core generation design.

Since these HC35 pieces are being done live from the auditorium, please excuse typos. Hot Chips is a crazy pace. Also, Intel’s slides had a lot of extra space around them. Apologies for that in this article, but getting an article out every 30 minutes does not allow for time to fix this.

Intel Xeon E-Cores for Next Gen Sierra Forest and More at Hot Chips 2023

Intel is acknowledging the industry trend toward there being an entire market segment for cloud-native computing. Here is the slide we saw earlier on the Granite Rapids deep dive that shows the market. Again, apologies for the additional white space.

This talk is focused on the E-core designs which will start with Sierra Forest.

Here is the new Sierra Forest microarchitecture. The codename is “Sierra Glen” per the previous talk today.

Intel has a new design specifically for lower and more efficient compute for cloud workloads. This is not like AMD’s approach of shrinking L3 cache size and area of compute dies. This is a different architecture.

Here is the 256 entry out of order window and the 22 ports.

Here is the breakdown between the different execution units in the E-cores.

On the memory side, we get a 4MB L2 cache. We also get Xeon features like L1 data cache ECC.

Intel has its new instructions like Intel VT-rp for security, and the new AI instructions for E-cores.

Each E-core is single-threaded, so these will not have Intel Hyper-Threading like the P-cores. They will not have AMX nor AVX-512. This will also not support full AVX10.

Here is an example package with the compute chiplet(s) and I/O chiplet(s). Intel is saying 144 cores per socket but 288 cores for dual socket systems. Intel says that there is a version with compute die and then two I/O dies on the Sierra Forest package. It feels like this compute die is not to scale.

Intel says this is for the density scale-out 1P and 2P servers, not scale-up (e.g. for an 8-socket Sierra Forest server.)

Great stuff from Hot Chips!

Final Words

Sierra Forest is an immensely important product for Intel. This is the company’s entry into cloud-native compute that it is missing at this point. It also means that Intel is set to more than double the number of cores per socket in less than 12 months.

We cannot wait to get Sierra Forest in the lab. A big question is what will happen with chips like AmpereOne and future CPUs from companies like AMD in the meantime. What is very exciting is that there will be multiple CPU segments.