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  1. JDK
  2. JDK-8017629

G1: UseSHM in combination with a G1HeapRegionSize > os::large_page_size() falls back to use small pages

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Details

    • Bug
    • Status: Resolved
    • P4
    • Resolution: Fixed
    • hs24, hs25
    • 9
    • hotspot
    • gc
    • b120

    Backports

      Description

        JDK-8007074 fixes crashes due to incorrect alignment with G1HeapRegionSize > os::large_page_size() and UseSHM (originally tracked by JDK-8016666) has been enabled, and if allocation of SHM/huge pages has actually been successful.

        With JDK-8007074, instead of crashing, if the memory area allocated returned by SHM functions is not aligned with G1HeapRegionSize (or actually the requested alignment), the VM falls back to use small pages.

        This kind of fallback is different to the fallback to use small pages when there are no (or not enough) large pages available at all.

        See os::reserve_memory_special_shm() for details.

        This may represent a performance issue.

        Improve that by e.g. manual alignment or additional allocation of small pages at the start and end to align the heap.

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            backported by

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8155011 G1: UseSHM in combination with a G1HeapRegionSize > os::large_page_size() falls back to use small pages

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8155012 G1: UseSHM in combination with a G1HeapRegionSize > os::large_page_size() falls back to use small pages

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8163631 G1: UseSHM in combination with a G1HeapRegionSize > os::large_page_size() falls back to use small pages

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8167738 G1: UseSHM in combination with a G1HeapRegionSize > os::large_page_size() falls back to use small pages

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved
            duplicates

            Bug - A problem which impairs or prevents the functions of the product. JDK-8054108 LargePages silently falling back to small pages with G1GC & 8GB+ heaps

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Closed
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-8016666 G1:UseSHM crashes the JVM if G1HeapRegionSize > os::large_page_size()

            • P3 - Major loss of function.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8007074 SIGSEGV at ParMarkBitMap::verify_clear()

            • P2 - Crashes, loss of data, severe memory leak.
            • Closed

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                stefank Stefan Karlsson
                tschatzl Thomas Schatzl
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                Dates

                  Created:
                  Updated:
                  Resolved: