With the arrival of recent kernel features (namely the dynamic pool and
multiple huge page sizes), comes increased configuration complexity. To
ease configuration for users, libhugetlbfs should provide a set of
library interfaces and a configuration program (hugecfg) so that the
system's hugetlb configuration can be easily displayed and modified.
Please reply with your feedback on my design below...
I have considered the following use cases for hugecfg:
* List all page sizes supported by the running kernel on this system and
indicate the default page size. Provide the pool counters for each size
(including nr_overcommit_hugepages)
* Display information about mounted hugetlbfs filesystems including:
path, page size and quota
* For a given page size, set the total number of pages (nr_hugepages)
* For a given page size, set the max number of pages
(nr_overcommit_huge_pages)
The above use cases in turn demand the following library API extensions:
/*
* Fill the array page_sizes[] with at most max_nr values corresponding
* to the supported huge page sizes for this system and kernel.
* Return the number of page sizes found or < 0 on error.
*/
int gethugepagesizes(long page_sizes[], int max_nr);
struct hugetlb_stat_pagesize {
unsigned long nr_hugepages;
unsigned long nr_overcommit_hugepages;
unsigned long free_hugepages;
unsigned long resv_hugepages;
unsigned long surplus_hugepages;
}
/*
* Populate the structure pointed to by stat with hugetlb pool counter
* values for the specified page size.
* Return 0 on success, other values to indicate an error.
*/
int hugetlb_stat_pagesize(long pagesize, struct hugetlb_stat_pagesize *stat);
/*
* Set, respectively, nr_hugepages and nr_overcommit_hugepages for the
* specified page size.
* Returns 0 if the setting was successful, other values to indicate an error.
*/
int hugetlb_set_nr_hugepages(long pagesize, unsigned long nr_pages);
int hugetlb_set_nr_overcommit_hugepages(long pagesize, unsigned long nr_pages);
Implementing the hugecfg utility would then become an orchestration of
libhugetlbfs API calls (except for mount point scanning which would
probably be implemented standalone in hugecfg). I envision the
following hugecfg command line usage:
hugecfg [options]
-S,--show-page-sizes - Show available page sizes and stats
-M,--show-mounts - Show mounted hugetlb filesystems
-p,--page-size - Operate on a specific page size
-n,--set-nr-hugepages - Set nr_hugepages for a specific size
-o,--set-nr-overcommit-hugepages - Set nr_overcommit_hugepages for a specific
size
--
Adam Litke - (agl at us.ibm.com)
IBM Linux Technology Center
-------------------------------------------------------------------------
This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
Build the coolest Linux based applications with Moblin SDK & win great prizes
Grand prize is a trip for two to an Open Source event anywhere in the world
http://moblin-contest.org/redirect.php?banner_id=100&url=/
_______________________________________________
Libhugetlbfs-devel mailing list
Libhugetlbfs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/libhugetlbfs-devel
