Details
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Enhancement
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Status: Resolved
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P4
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Resolution: Fixed
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8-shenandoah, 11-shenandoah, 13, 14, 15
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b15
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generic
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generic
Backports
| Issue | Fix Version | Assignee | Priority | Status | Resolution | Resolved In Build |
|---|---|---|---|---|---|---|
| JDK-8243600 | 14.0.2 | Roman Kennke | P4 | Resolved | Fixed | b04 |
Description
The strong invariant gives us an opportunity to short-cut arraycopy-barriers:
- if the src object is beyond the safe-iteration limit, e.g. has been allocated since evac-start, then it can not have any from-space references and thus does not require updating.
- likewise, if the dst object is beyond TAMS, e.g. has been allocated since mark-start, then it can only have references that must have been reachable otherwise and thus don't require enqueueing in SATB.
Short-cutting on those condition cuts out 80-90% of arraycopy slowpaths.
- if the src object is beyond the safe-iteration limit, e.g. has been allocated since evac-start, then it can not have any from-space references and thus does not require updating.
- likewise, if the dst object is beyond TAMS, e.g. has been allocated since mark-start, then it can only have references that must have been reachable otherwise and thus don't require enqueueing in SATB.
Short-cutting on those condition cuts out 80-90% of arraycopy slowpaths.
Attachments
Issue Links
- backported by
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JDK-8243600 Shenandoah: Short-cut arraycopy barriers
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- Resolved
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- relates to
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JDK-8241081 Shenandoah: Do not modify update-watermark concurrently
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- Closed
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- Resolved
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