8346005: Parallel: Incorrect page size calculation with UseLargePages

[albertnetymk]

Refactor the heap-space and OS memory interface code to clearly separate two related but distinct concepts: alignment and os-page-size. These are now represented as two fields in PSVirtualSpace.

The parallel heap consists of four spaces: old, eden, from, and to. The first belongs to the old generation, while the latter three belong to the young generation.

The size of any space is always aligned to alignment, which also determines the unit for resizing. To keep the implementation simple while allowing flexible per-space commit and uncommit operations, each space must contain at least one OS page. As a result, alignment is always greater than or equal to os-page-size.

When using explicit large pages -- which require pre-allocating large pages before the VM starts -- the actual OS page size is not known until the heap has been reserved. The additional logic in ParallelScavengeHeap::initialize detects the OS page size in use and adjusts alignment if necessary.

Test: tier1–8

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8346005: Parallel: Incorrect page size calculation with UseLargePages (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/26700/head:pull/26700
$ git checkout pull/26700

Update a local copy of the PR:
$ git checkout pull/26700
$ git pull https://git.openjdk.org/jdk.git pull/26700/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 26700

View PR using the GUI difftool:
$ git pr show -t 26700

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/26700.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back ayang! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@albertnetymk The following label will be automatically applied to this pull request:

• hotspot

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

[albertnetymk]

/cc hotspot-gc

[openjdk]

@albertnetymk
The hotspot-gc label was successfully added.

[mlbridge]

Webrevs

• 00: Full (0a67ca44)