Article ID: 000089477 Content Type: Maintenance & Performance Last Reviewed: 02/14/2022

Initializing an Intel® Software Guard Extensions (Intel® SGX) Enclave with a Large Heap Size Is Slow


Cause and mitigation for slow allocation of large amount of memory for an enclave.

  • Initializing an enclave with HeapInitSize of a few megabytes takes less than one second.
  • Initalizing an enclave with large HeapInitSize, for example, 1 GB, takes several seconds.

It is expected that initializing large amounts of memory for an enclave heap will take a long time. Initializing and adding memory to the Enclave Page Cache (EPC) for an enclave is much more complex than a simple memory allocation in a regular application. Before a chunk of memory is added to the EPC it must go through several security checks, including being measured using a 256-bit SHA-2 secure hash function.

Refer to sections 5.1, 5.3, 5.6 in SGX Explained, and the EADD and EEXTEND instructions in Intel SGX Enclave Lifecycle.

If the processor supports Intel® Software Guard Extensions (Intel® SGX) SGX2, in the Enclave Configuration File:

HeapInitSize is the amount to fully initialize (i.e. EADD the page then EEXTEND it) at enclave launch, which takes time. With a minimal initialization size, it would be quicker, and the rest of the memory would only be added utilizing the SGX2 instructions when allocated, via malloc, by the enclave during runtime.

Related Products

This article applies to 1 products