Fix Version/s: 16
Compatibility Risk Description:Evaluation always showed a performance improvement. Users who previously specified a nonsensical value < page size will get an error to update their specification.
Quick searching on the web indicated no particular usage of this flag.
Interface Kind:add/remove/modify command line option
PreTouchParallelChunkSize default value for improved performance.
The current value of
PreTouchParallelChunkSize has originally been set according to some ad-hoc testing. Further, more extensive testing showed that the time to pre-touch memory can be improved by almost 15% by adjusting this value.
This can have significant impact on startup time with
Set new default value for
PreTouchParallelChunkSize to 4MB. JDK-8254699 contains a spreadsheet with an exhaustive performance test showing this value to be best overall.
Also change minimal size of this value to a (small) page size.
\ - product(size_t, PreTouchParallelChunkSize, 1 * G, \ + product(size_t, PreTouchParallelChunkSize, 4 * M, \ "Per-thread chunk size for parallel memory pre-touch.") \ - range(1, SIZE_MAX / 2) \ + range(4*K, SIZE_MAX / 2) \ \