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eclipse-openj9 / openj9

Eclipse OpenJ9: A Java Virtual Machine for OpenJDK that's optimized for small footprint, fast start-up, and high throughput. Builds on Eclipse OMR (https://github.com/eclipse/omr) and combines with the Extensions for OpenJDK for OpenJ9 repo.
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verbose:sizes doesn't show all supported pagesizes #14438

Closed zl-wang closed 2 years ago

zl-wang commented 2 years ago

with the latest JDK on ppc64le ... java -verbose:sizes -version

  .......
  -Xlp:objectheap:pagesize=64K   large page size
                  available large page sizes:
                  64K
  -Xlp:codecache:pagesize=64K    large page size for JIT code cache
                  available large page sizes for JIT code cache:
                  64K
  -Xmso512K       operating system thread stack size
  -Xiss2K         java thread stack initial size
  -Xssi16K        java thread stack increment
  -Xss1M          java thread stack maximum size
  -XX:SharedCacheHardLimit=0K shared class cache size
  -Xscmx0K        shared class cache soft max size
  -Xscdmx0K       reserved shared class cache space for class debug attributes
  -Xscminaot0K    min reserved shared class cache space for AOT
  -Xscmaxaot0K    max allowed shared class cache space for AOT
  -Xscminjitdata0K min reserved shared class cache space for JIT data
  -Xscmaxjitdata0K max allowed shared class cache space for JIT data
openjdk version "17.0.2" 2022-01-18
IBM Semeru Runtime Open Edition 17.0.2.0 (build 17.0.2+8)
Eclipse OpenJ9 VM 17.0.2.0 (build openj9-0.30.0, JRE 17 Linux ppc64le-64-Bit Compressed References 20220127_101 (JIT enabled, AOT enabled)
OpenJ9   - 9dccbe076
OMR      - dac962a28
JCL      - 64cd399ca28 based on jdk-17.0.2+8)

at least, another 2MB pagesize is supported (pages of that size might not be configured yet). something seemed wrong.

dmitripivkine commented 2 years ago

JVM on Linux reads /proc/meminfo file and search for HugePages_Total:, HugePages_Free:,Hugepagesize:. In order for Huge Pages to be enabled Hugepagesize: and HugePages_Total: should be larger than zero both. @zl-wang Would you please check this file?

zl-wang commented 2 years ago

ah, the total is 0, size is 2048k. so, the verbose listing has different meaning between (e.g.) AIX and Linux.

On AIX, i saw listing below: (although total pages of 16m/16g are 0 too)

  -Xlp:objectheap:pagesize=64K   large page size
                  available large page sizes:
                  4K
                  64K
                  16M
                  16G
  -Xlp:codecache:pagesize=64K    large page size for JIT code cache
                  available large page sizes for JIT code cache:
                  64K
                  16M