Comment 3 for bug 1843942

Reviewed: https://review.opendev.org/685976
Committed: https://git.openstack.org/cgit/starlingx/utilities/commit/?id=45a149497ee8d05b571328214c2c819c63ea9ea9
Submitter: Zuul
Branch: master

commit 45a149497ee8d05b571328214c2c819c63ea9ea9
Author: Jim Gauld <email address hidden>
Date: Tue Oct 1 09:39:57 2019 -0400

    Affine NVMe disk interrupts to platform cores

    This affines NVMe disk interrupts to platform cores for low-latency
    worker configurations to reduce application jitter. Tasks with names
    matching irq/<pid>-nvme* get re-affined.

    This also corrects writing of related affinity settings for:
    - /proc/irq/default_smp_affinity
    - /sys/devices/virtual/workqueue/cpumask
    - /sys/bus/workqueue/devices/writeback/cpumask

    The platform coremasks require being delimited with commas every 8 hex
    characters. HT-enabled hosts tend to have very large affinity masks,
    e.g., host with 88 CPUs, the coremask for the cpulist 0-1,44-45 is:
    00000000,00000000,00000000,00003000,00000000,00000003

    Just writing 30000000000000000003 will produce the following error:
    echo: write error: Value too large for defined data type

    Change-Id: Ibad5beffc791b796e472ff19950cf6a3e973be86
    Closes-bug: 1843942
    Signed-off-by: Jim Gauld <email address hidden>