RFR: 8268127: Shenandoah: Heap size may be too small for region to align to large page size [v4]
rkennke at openjdk.java.net
Tue Jun 8 16:42:25 UTC 2021
On Mon, 7 Jun 2021 13:04:41 GMT, Zhengyu Gu <zgu at openjdk.org> wrote:
>> TestLargePages.java failed on Linux AArch64, where large page size is 500M, and the test is configured to run with much smaller heap, e.g. 131M.
>> This is *not* AArch64 specific, just none of our regular test machines has large page setup.
>> I purpose two invariants:
>> 1) Heap size always aligns up to page size that is requested.
>> 2) Region size always aligns up to page size that is requested if heap is large enough to accommodate them. Otherwise, it aligns up to regular page size.
>> This partially reverts JDK-8266802.
>> Obviously, this is a corner case and is unlikely seen in real word. The alternative is to disable UseLargePages if heap size is too small, e.g. align_up(heap_size, page_size) < MIN_NUM_REGIONS.
> Zhengyu Gu has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:
> - rkennke's comment
> - Merge branch 'master' into JDK-8268127-large-page-small-heap
> - Window build
> - Fix compilation error
> - v2
> - v1
Marked as reviewed by rkennke (Reviewer).
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