[8u] RFR 8248214: Add paddings for TaskQueueSuper to reduce false-sharing cache contention

[Hohensee, Paul]

Lgtm.

Paul

On 10/26/20, 6:19 AM, "jdk8u-dev on behalf of Zhengyu Gu" <jdk8u-dev-retn at openjdk.java.net on behalf of zgu at redhat.com> wrote:

    I would like to backport this patch to OpendJDK 8u for parity with
    Oracle 8u281.

    The original patch does not apply cleanly.

    There is a conflict on copyright year of taskqueue.hpp

    - * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights
    reserved.
    + * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights
    reserved.

    Besides, 8u does not have DEFINE_PAD_MINUS_SIZE macro, which is
    introduced by JDK-8049737, that is used to pad the variable. This patch
    imported the macro from 11u.

    The original bug: https://bugs.openjdk.java.net/browse/JDK-8248214
    The original patch:
    https://hg.openjdk.java.net/jdk-updates/jdk11u/rev/08c734477683


    8u webrev: http://cr.openjdk.java.net/~zgu/JDK-8248214-8u/webrev.00/


    Thanks,

    -Zhengyu