XCI - Marvell Thunder X2

Cray XC50 cabinet, codenamed XCI, containing 20’992 ARM cores. Available since November 2018, expanded September 2020.

  • Marvell ThunderX2 ARM v8.1

    • 16nm FinFET CPU @ 2.1GHz (permanent turbo to 2.5GHz)

    • 4-way simultaneous multi-threading

    • 128-bit SIMD “NEON”

    • 32KB L1 instruction & data cache, 256KB L2 per core, 32MB distributed L3 cache

    • 8 DDR4 DIMMs @ 2666MHz * 160 nodes of 256GB, 169 nodes of 512GB

    • Cray Aries interconnect in dragonfly topology operating at 14Gbps~

  • Cray Linux Environment 7 (Suse SLES 15)

    • Cray Programming Environment


Work is submitted via the arm queue.

There is also an arm-dev queue for running interactive development jobs up to three hours in duration. To specify an interactive job add the -I flag to your qsub command.

To target the larger memory nodes, add the following to your job script:

#PBS -l mem=500GB


The default python version on login nodes is a system-bundled version, be sure to load a version of cray-python.

Known errors

Some Cray compilers will emit this error message:

No supported cpu target is set, CRAY_CPU_TARGET=aarch64 will be used.
Load a valid targeting module or set CRAY_CPU_TARGET

To silence this message and to ensure the correct CPU optimisations are applied, run the following before using the compiler:

module load craype-arm-thunderx2