Changing memory page size

Question

i was reading there,that the number of virtual memory pages are equal to number of physical memory frames and that the size of frames and that of pages are equal,like for my 32bit system the page size is 4096.

Well i was thinking is there there any way to change the page size or the frame size?

I am using Linux OS. I have searched a lot and what I found is,we can change the page size or in fact we can increase the page size by shifting to huge pages.Is there any other way to change (increase or decrease) or set the page size of our choice?

(Not coding anything,a general question)

Answer 1

In practice it is (nearly) impossible to "change" the memory page size, since the page size is known & determined by the MMU hardware, so the operating system is taking that into account. However, notice that some Linux systems (and hardware!) have hugetlbpage and Linux mmap(2) might accept MAP_HUGETLB (but your code should handle the case of processors or kernels without huge page support, e.g. by calling mmap again without MAP_HUGETLB when the first mmap with MAP_HUGETLB has failed).

^{From what I read, on some Linux systems, you can use hugetlbpage with various sizes. But the sysadmin can restrict these (or some kernels disable it), so your code should always be prepared that a mmap with MAP_HUGETLB fails.}

Even with those "huge pages", the page size is not arbitrary. Use sysconf(_SC_PAGE_SIZE) on POSIX systems to get the standard page size (it is usually 4Kbytes). See also sysconf(3)

AFAIK, even on systems with hugetlbpage feature, mmap can be called without MAP_HUGETLB and the page size (as reported by sysconf(_SC_PAGE_SIZE)) is still 4Kbytes. Perhaps some recent kernels with some weird configurations are using huge pages everywhere, and IIRC some kernels might be configured with 1Mbyte page (i am not sure about that and I might be wrong)...