Remove requirement for consistent page size in SCC

[hangshao0]

The page level operation in SCC are msync and mprotect. msync is only used on z/OS, we can always do msync if we can have a valid _osPageSize. For mprotect, it is turned off if the SCC is readonly. If the data is not paged aligned anymore, mprotect should \also be turned off. There is no need to force consistent memory page size anymore.

Fixes #19968

[pshipton]

Any idea why the cache isn't mprotected when read-only? Except on z/OS, it seems the entire read-only cache should be mprotected.

Pls add a test flag so page size differences can be automatically tested.

[pshipton]

I'm wondering if the two page sizes should be output in the javacore and printstats output, for easier diagnostics.

[hangshao0]

Any idea why the cache isn't mprotected when read-only?

There are open readonly, so they are memory protected.

Discussed with Peter in person, I will add a test option and test cases that takes fake memory page size. We can add the page size information in the printTopLayerstats and javacore.

[tajila]

@hangshao0 Any update on this?

[hangshao0]

Any update on this?

Currently working other item having higher priority. I will come back working on this shortly.

[tajila]

@pshipton Please take a look

[pshipton]

Tested internally.