Containers report one extra CPU core

[Sangeppato]

Description

In Docker Desktop 4.24 the containers see one extra CPU core compared to the ones actually available to the VM

Reproduce

1. Check the number of CPU cores allocated in the Resources settings
2. Check the actual number of cores seen by any container running lscpu (or even in the "Containers" view in the Dashboard)

Expected behavior

The correct number of CPU cores should be seen

docker version

Client:
 Cloud integration: v1.0.35+desktop.5
 Version:           24.0.6
 API version:       1.43
 Go version:        go1.20.7
 Git commit:        ed223bc
 Built:             Mon Sep  4 12:28:49 2023
 OS/Arch:           darwin/arm64
 Context:           desktop-linux

Server: Docker Desktop 4.24.0 (122432)
 Engine:
  Version:          24.0.6
  API version:      1.43 (minimum version 1.12)
  Go version:       go1.20.7
  Git commit:       1a79695
  Built:            Mon Sep  4 12:31:36 2023
  OS/Arch:          linux/arm64
  Experimental:     false
 containerd:
  Version:          1.6.22
  GitCommit:        8165feabfdfe38c65b599c4993d227328c231fca
 runc:
  Version:          1.1.8
  GitCommit:        v1.1.8-0-g82f18fe
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client:
 Version:    24.0.6
 Context:    desktop-linux
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.11.2-desktop.5
    Path:     /Users/lll/.docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v2.22.0-desktop.2
    Path:     /Users/lll/.docker/cli-plugins/docker-compose
  dev: Docker Dev Environments (Docker Inc.)
    Version:  v0.1.0
    Path:     /Users/lll/.docker/cli-plugins/docker-dev
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.20
    Path:     /Users/lll/.docker/cli-plugins/docker-extension
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v0.1.0-beta.8
    Path:     /Users/lll/.docker/cli-plugins/docker-init
  sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc.)
    Version:  0.6.0
    Path:     /Users/lll/.docker/cli-plugins/docker-sbom
  scan: Docker Scan (Docker Inc.)
    Version:  v0.26.0
    Path:     /Users/lll/.docker/cli-plugins/docker-scan
  scout: Docker Scout (Docker Inc.)
    Version:  v1.0.7
    Path:     /Users/lll/.docker/cli-plugins/docker-scout

Server:
 Containers: 1
  Running: 0
  Paused: 0
  Stopped: 1
 Images: 1
 Server Version: 24.0.6
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 8165feabfdfe38c65b599c4993d227328c231fca
 runc version: v1.1.8-0-g82f18fe
 init version: de40ad0
 Security Options:
  seccomp
   Profile: unconfined
  cgroupns
 Kernel Version: 6.4.16-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: aarch64
 CPUs: 4
 Total Memory: 7.765GiB
 Name: docker-desktop
 ID: dcb3c291-6f9d-4490-8cdf-c12a999bc5b2
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 No Proxy: hubproxy.docker.internal
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5555
  127.0.0.0/8
 Live Restore Enabled: false

WARNING: daemon is not using the default seccomp profile

Diagnostics ID

7534C0A5-9659-4A6B-A7E3-299BBD4B9F2C/20231003151833

Additional Info

• Resources settings:

• Containers view:

EDIT:

• When running stress inside a container I can see that the VM utilizes the correct number of cores.

• Inside a container nproc reports the correct number of cores, while nproc --all lscpu and cat /proc/cpuinfo all report one extra core. So it looks like the VM has access to one extra core but each process is limited to the correct number (as indicated by nproc)?

[alexeykhan]

Experiencing the same problem:
Version: 4.24.0 (122432)

docker version

Client:
Cloud integration: v1.0.35+desktop.5
Version: 24.0.6
API version: 1.43
Go version: go1.20.7
Git commit: ed223bc
Built: Mon Sep 4 12:28:49 2023
OS/Arch: darwin/arm64
Context: desktop-linux

Server:
Docker Desktop 4.24.0 (122432)
Engine:
Version: 24.0.6
API version: 1.43 (minimum version 1.12)
Go version: go1.20.7
Git commit: 1a79695
Built: Mon Sep 4 12:31:36 2023
OS/Arch: linux/arm64
Experimental: false
containerd:
Version: 1.6.22
GitCommit: 8165feabfdfe38c65b599c4993d227328c231fca
runc:
Version: 1.1.8
GitCommit: v1.1.8-0-g82f18fe
docker-init:
Version: 0.19.0
GitCommit: de40ad0

Additional Info

Having only 8 cores, docker shows 9 cores allocated (the same for any N set as cpu limit docker shows N+1 cores allocated).

Resources settings:

Containers view:

[taxoakumi2810]

Hello.

I have installed CPU resources of 56 cores, but containersview only has 10 cores allocated.
I do not understand why?

[Sangeppato]

Looks like it's fixed in 4.25.0