P4
On some machines, G1 does not use the large pages in the size specified by the user, e.g. when using -XX:+UseLargePages -XX:LargePageSizeInBytes=256M it does not use 256M large pages.
Other collectors use large pages of that size.
E.g. for
java -server -Xms512g -Xmx512g -Xmn256g -XX:ParallelGCThreads=64 -XX:+UseG1GC -XX:LargePageSizeInBytes=256m <application>
pmap -xs shows that there are no 256M pages in use.
On the same machine with another application, with a preliminary fix to print G1 heap sizes indicates that 256M pages are at least requested:
> G1 heap: min=3298534883328 max=3298534883328 pg_sz=268435456
> base=0xfffffcfd80000000 size=3298534883328
Other collectors use large pages of that size.
E.g. for
java -server -Xms512g -Xmx512g -Xmn256g -XX:ParallelGCThreads=64 -XX:+UseG1GC -XX:LargePageSizeInBytes=256m <application>
pmap -xs shows that there are no 256M pages in use.
On the same machine with another application, with a preliminary fix to print G1 heap sizes indicates that 256M pages are at least requested:
> G1 heap: min=3298534883328 max=3298534883328 pg_sz=268435456
> base=0xfffffcfd80000000 size=3298534883328