Comment 3 for bug 1924209

Reviewed: https://review.opendev.org/c/starlingx/stx-puppet/+/786354
Committed: https://opendev.org/starlingx/stx-puppet/commit/94ec35ff2d5363d3816f6d267a77a4efba6c6aa8
Submitter: "Zuul (22348)"
Branch: master

commit 94ec35ff2d5363d3816f6d267a77a4efba6c6aa8
Author: Zhixiong Chi <email address hidden>
Date: Wed Apr 14 23:28:03 2021 -0400

    Increase min_free_kbytes to 256M for storage to avoid OOM issue

    Help to prevent the OOM issue that it failed to allocate memory
    with error message 'page allocation failure: order:2, mode:0x104020'

    As the min_free_kbytes in the linux documentation shows:
    This is used to force the Linux VM to keep a minimum number
    of kilobytes free. The VM uses this number to compute a
    watermark[WMARK_MIN] value for each lowmem zone in the system.
    Each lowmem zone gets a number of reserved free pages based
    proportionally on its size.

    Keeping more memory free in those zones means that the os itself is
    less likely to run out of memory during high memory pressure and high
    allocation events.

    Based on the issue occurs on the storage node so far, we only update
    the value for the storage node.

    Closes-Bug: #1924209

    Change-Id: Iae2e5a0787f69c62ba5da53663371fd2be148e15
    Signed-off-by: Zhixiong Chi <email address hidden>