Corner cases are slightly non-obvious problems implementing huge pages. If you think of one, please archive it here so it doesn't come back and bite us later.
* NUMA-aware allocation - don't want all the memory accesses going through one controller! See [[http://www-941.ibm.com/collaboration/wiki/display/LinuxP/Tuning+stream+with+libhugetlbfs|IBM's page about tuning Stream]].
* STREAM and hugetlb is a huge issue unless you have chipset level interleave no matter what
* Fork of an application with huge pages when no huge pages are left - must fail over to small pages.
* mmap of a file that is partially in cache already
* mmap of a file that then gets replaced on disk
. (say glibc text and then glibc gets upgraded to a newer version)
* MAP_GROWSDOWN for stacks including automatic growth
* mprotect to executable (scenario: dlopen of a shared lib that
. requires executable stack, causing all thread stacks to be
mprotected executable)
* write() of mmaped area to the same file at an offset either
. inside or outside the same 2Mb page
* same but for an O_DIRECT write
* same but for AIO write
* sendfile() of a non-4Kb region
* truncate of 4Mb mmaped file to 1Mb, then truncate to 1.5Mb
. then 0.5Mb (creates a sparse file)
* mmap of a 2Mb region in 2 parts: first 1Mb gets mmaped writable private,
. second 2Mb gets mmaped shared writable; then write a few bytes to each part
* Running a large .bss segment workload, specifying only a portion
of the large page requirements to be made available to the
workload... ie: app defines 10GB in arrays, but only 5GB are
* whether an entire segment must be dedicated to huge pages
(256MB in the ppc environment) if one huge page is specified
Should huge pages be allocated by segment?
* can we define stages of transparent functionality to enable
customer production usage in the near future?
* can a non-root userid be specified to have access to huge
pages? in a production environment, admins may require
ability to designate huge page users..
