Details
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Enhancement
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Resolution: Fixed
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P4
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15, 17, 18
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b13
Description
Currently G1 clears the whole (next) mark bitmaps of the regions of the entire (committed) heap.
This is unnecessary, only bitmaps of regions that were dirtied need clearing. SinceJDK-8197850 we track how much live data has been encountered during mark for every region, corresponding to the live objects we set a mark between bottom and ntams.
I.e. first, we only need to clear between [bottom, ntams[, and second only clear bitmaps which regions had at least one bit set (i.e. have some live data).
This is also a very interesting optimization forJDK-8240556
This is unnecessary, only bitmaps of regions that were dirtied need clearing. Since
I.e. first, we only need to clear between [bottom, ntams[, and second only clear bitmaps which regions had at least one bit set (i.e. have some live data).
This is also a very interesting optimization for
Attachments
Issue Links
- relates to
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JDK-8197850 Calculate liveness in regions during marking
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- Resolved
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JDK-8240556 Abort concurrent mark after effective eager reclamation of humongous objects
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- Resolved
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