Large page support

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Large page support entails support for the Linux® hugetlbfs file system.

The large page support virtual file system is backed by larger memory pages than the usual 4 K pages; for IBM Z®, the hardware page size is 1 MB.

To check whether 1 MB large pages are supported in your environment, issue the command:
# grep edat /proc/cpuinfo 
features        : esan3 zarch stfle msa ldisp eimm dfp edat etf3eh highgprs te
An output line that lists edat as a feature indicates 1 MB large page support.

Applications that use large page memory save a considerable amount of page table memory. Another benefit from the support might be an acceleration in the address translation and overall memory access speed.

SUSE Linux Enterprise Server 12 SP4 supports libhugetlbfs linking. For more information, see the libhugetlbfs package and the how-to document that is included in the package.

SUSE Linux Enterprise Server 12 SP4 also supports transparent hugepages. For more information, see Documentation/vm/transhuge.txt in the Linux source tree.

As of zEC12, you can also configure 2 GB large pages if Linux is running on an LPAR. There is no flag that indicates 2 GB support; the support is always there as of zEC12.