hugetlbfs allocates huge pages from the global pool as needed. Even if the global pool contains a sufficient number pages for the filesystem size at mount time, those global pages could be grabbed for some other use. As a result, filesystem huge page allocations may fail due to lack of pages. Applications such as a database want to use huge pages for performance reasons. hugetlbfs filesystem semantics with ownership and modes work well to manage access to a pool of huge pages. However, the application would like some reasonable assurance that allocations will not fail due to a lack of huge pages. At application startup time, the application would like to configure itself to use a specific number of huge pages. Before starting, the application can check to make sure that enough huge pages exist in the system global pools. However, there are no guarantees that those pages will be available when needed by the application. What the application wants is exclusive use of a subset of huge pages. Add a new hugetlbfs mount option 'min_size=<value>' to indicate that the specified number of pages will be available for use by the filesystem. At mount time, this number of huge pages will be reserved for exclusive use of the filesystem. If there is not a sufficient number of free pages, the mount will fail. As pages are allocated to and freeed from the filesystem, the number of reserved pages is adjusted so that the specified minimum is maintained. V2: Added ability to specify minimum size. (David Rientjes) V1: Comments from RFC addressed/incorporated Mike Kravetz (4): hugetlbfs: add minimum size tracking fields to subpool structure hugetlbfs: add minimum size accounting to subpools hugetlbfs: accept subpool min_size mount option and setup accordingly hugetlbfs: document min_size mount option Documentation/vm/hugetlbpage.txt | 21 ++++-- fs/hugetlbfs/inode.c | 75 ++++++++++++++++----- include/linux/hugetlb.h | 5 +- mm/hugetlb.c | 138 ++++++++++++++++++++++++++++++++------- 4 files changed, 190 insertions(+), 49 deletions(-) -- 2.1.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>