Help Center/ Elastic Cloud Server/ User Guide/ Instances/ Managing My ECSs/ Enabling or Disabling Magic Core
Updated on 2026-04-24 GMT+08:00
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Enabling or Disabling Magic Core

Scenarios

Magic core is a CPU hyper-threading capability provided by ECSs for high-concurrency scenarios. You can dynamically adjust the number of vCPUs in an ECS to balance compute density.
  • Enabled: Recommended for workloads requiring higher compute density and concurrency, such as web services, middleware, big data processing, lightweight virtualization, and batch tasks. In these scenarios, enabling magic core can improve the compute throughput of each ECS.
  • Disabled: Recommended for pure compute-intensive workloads that demand high single-core performance and stability, such as HPC, simulation, and rendering. In these scenarios, disabling magic core can reduce thread contention and improve efficiency and consistency.

You can enable or disable magic core when purchasing Kunpeng ECSs or modifying their specifications. Magic core is disabled by default.

Background

Certain Kunpeng ECS flavors support Kunpeng magic core (a feature logically similar to hyper-threading). A CPU core can have two vCPUs concurrently available for different workloads.

A flavor defines the number of vCPUs. You can query the actual number of vCPUs from a Kunpeng ECS. For details, see Querying the Number of vCPUs from an ECS.

Magic core is disabled for Kunpeng ECSs by default.

  • If magic core is disabled (default setting), the number of vCPUs queried from the ECS is the same as the number of vCPUs defined by the flavor.
  • If magic core is enabled, the number of vCPUs queried from the ECS is twice the number of vCPUs defined by the flavor.

For example, the kc2.large.2 flavor defines two vCPUs.

  • If magic core is disabled, the number of vCPUs queried from the ECS is 2.
  • If magic core is enabled, the number of vCPUs queried from the ECS is 4.

Constraints

  • For details about the ECS flavors that support magic core, see Kunpeng ECS Specifications.
  • Enabling or disabling magic core does not generate additional costs.
  • After a Kunpeng ECS is purchased, you cannot directly change the magic core status. To do so, you can change its flavor to change the magic core status.

Enabling or Disabling Magic Core (During ECS Purchase)

  1. Go to the Buy ECS page.

    Configure parameters required for purchasing ECSs, including basic, instance, and OS settings. For details, see Purchasing an ECS in Custom Config Mode.

  2. Set CPU Options in Advanced Settings to enable or disable magic core.
    Figure 1 Specifying CPU options
    • If you select Enable magic core (with hyper-threading), magic core is enabled.
    • If you do not select Enable magic core (with hyper-threading) (the default setting), magic core is disabled.
  3. Confirm the settings and complete the ECS purchase.

Enabling or Disabling Magic Core (During ECS Flavor Change)

  1. Log in to the ECS console and access the ECS list page.
  2. In the ECS list, locate the row that contains the target ECS and choose More > Modify Specifications in the Operation column.

    The Modify ECS Specifications page is displayed.

  3. Select a new ECS type, vCPUs, and memory.

    Before modifying specifications, you need to stop the ECS manually or select Authorize ECS auto-stop.

    Before modifying specifications, you need to stop the ECS manually or select Authorize ECS auto-stop.

  4. Click Next.
  5. Confirm the settings, read and agree to the agreement, and then click Submit Application.

    After the modification is complete, you can query the actual number of vCPUs from the ECS by referring to Querying the Number of vCPUs from an ECS.

Querying the Number of vCPUs from an ECS

You can log in to an ECS and query the number of vCPUs.
  1. Log in to an ECS.
  2. Query the number of vCPUs from the ECS.

    lscpu

    As shown in Figure 2, CPU(s) indicates the number of vCPUs.

    In the following example, magic core is enabled for the kc2.large.2 flavor with 2 vCPUs and 4 GiB of memory. The actual number of vCPUs queried from the ECS is 4.

    Figure 2 Result
Parent Topic: Managing My ECSs