Is the EPC size seperate from the RAM memory size or already included?

Question

Hi, I deploy Standard_DC8s_v3 machine, and from the website (https://learn.microsoft.com/en-us/azure/virtual-machines/sizes/general-purpose/dcsv3-series?tabs=sizebasic) I know that it has 64 GB RAM memory and 32 GB EPC.

However, I wonder if the EPC size is seperately counted from the RAM memory size or already included in the 64 GB ram memory size?

E.g., if the EPC is included in the ram memory size, then the max memory I can use for my intel SGX is 64 GB. Otherwise, if the EPC size is countted seperatly from the ram size, then I can run an enclave at a size of 32 GB + 64 GB = 96 GB at maximum.

Thank you very much! Lookforward to your reply!

-Sean.

Answer 1

Hi Sean,

Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.

DCsv3-Series and DCdsv3-Series VMs are the latest generation of Intel SGX machines. In this generation, CPU Cores have increased 6x (up to a maximum of 48 cores), Encrypted Memory (EPC) has increased 1500x to 256GB, Regular Memory has increased 12x to 384GB. All these changes substantially improve the performance gen-on-gen and unlock entirely new scenarios. These VMs also support Intel Total Memory Encryption (TME).

Each enclave has an encrypted page cache (EPC) with a set size. The EPC determines the amount of memory that an enclave can hold. DCsv2-series VMs hold up to 168 MiB. DCsv3/DCdsv3-series VMs hold up to 256 GB for more memory-intensive workloads. The EPC is a specific portion of memory reserved for Intel Software Guard Extensions (SGX) enclaves.

You can check the RAM size using system information.

or In the System Information window, click System Summary on the left sidebar. Total Physical Memory: This refers to the total amount of physical RAM installed on your system. Available Physical Memory: It represents the amount of physical RAM that is currently unused and available for immediate use by applications.

The EPC is a dedicated cache for Intel SGX enclaves, and it's not part of the system's RAM. This means that you can use the 64 GB of RAM for your application, and in addition, you can use up to 32 GB of EPC for your Intel SGX enclave. In contrast, the general RAM is used by the operating system and all applications running on the system, and its size can be much larger, typically ranging from a few gigabytes to several terabytes.
https://learn.microsoft.com/en-us/azure/confidential-computing/confidential-computing-enclaves

If you have any further queries, do let us know.

If the answer is helpful, please click "Accept Answer" and "Upvote it."