arch

The arch directive defines the CPU architecture to build the software in use by the process' task. For example:

process blast {
    spack 'blast-plus@2.13.0'
    arch 'linux/x86_64', target: 'cascadelake'

    script:
    """
    blastp -query input_sequence -num_threads ${task.cpus}
    """
}

The example above declares that the CPU generic architecture is linux/x86_64 (X86 64 bit), and more specifically that the microarchitecture is cascadelake (a specific generation of Intel CPUs).

This directive is currently used by the following Nextflow functionalities:

• by the spack directive, to build microarchitecture-optimized applications;
• by the Wave service, to build containers for one of the generic families of CPU architectures (see below);
• by the spack strategy within Wave, to optimize the container builds for specific CPU microarchitectures.

Allowed values for the arch directive are as follows, grouped by equivalent family (choices available for the sake of compatibility):

• X86 64 bit: linux/x86_64, x86_64, linux/amd64, amd64
• ARM 64 bit: linux/aarch64, aarch64, linux/arm64, arm64, linux/arm64/v8
• ARM 64 bit, older generation: linux/arm64/v7

Examples of values for the architecture target option are cascadelake, icelake, zen2 and zen3. See the Spack documentation for the full and up-to-date list of meaningful targets.