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hugetlb: new sysfs interface

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Provide new hugepages user APIs that are more suited to multiple hstates
in sysfs.  There is a new directory, /sys/kernel/hugepages.  Underneath
that directory there will be a directory per-supported hugepage size,
e.g.:

/sys/kernel/hugepages/hugepages-64kB
/sys/kernel/hugepages/hugepages-16384kB
/sys/kernel/hugepages/hugepages-16777216kB

corresponding to 64k, 16m and 16g respectively.  Within each
hugepages-size directory there are a number of files, corresponding to the
tracked counters in the hstate, e.g.:

/sys/kernel/hugepages/hugepages-64/nr_hugepages
/sys/kernel/hugepages/hugepages-64/nr_overcommit_hugepages
/sys/kernel/hugepages/hugepages-64/free_hugepages
/sys/kernel/hugepages/hugepages-64/resv_hugepages
/sys/kernel/hugepages/hugepages-64/surplus_hugepages

Of these files, the first two are read-write and the latter three are
read-only.  The size of the hugepage being manipulated is trivially
deducible from the enclosing directory and is always expressed in kB (to
match meminfo).

[dave@linux.vnet.ibm.com: fix build]
[nacc@us.ibm.com: hugetlb: hang off of /sys/kernel/mm rather than /sys/kernel]
[nacc@us.ibm.com: hugetlb: remove CONFIG_SYSFS dependency]
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nishanth Aravamudan
2008-07-23 21:27:44 -07:00
committed by Linus Torvalds
parent a137e1cc6d
commit a343787016
4 changed files with 262 additions and 66 deletions
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23
Documentation/vm/hugetlbpage.txt
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@@ -95,6 +95,29 @@ this condition holds, however, no more surplus huge pages will be
allowed on the system until one of the two sysctls are increased
sufficiently, or the surplus huge pages go out of use and are freed.
With support for multiple hugepage pools at run-time available, much of
the hugepage userspace interface has been duplicated in sysfs. The above
information applies to the default hugepage size (which will be
controlled by the proc interfaces for backwards compatibility). The root
hugepage control directory is
/sys/kernel/mm/hugepages
For each hugepage size supported by the running kernel, a subdirectory
will exist, of the form
hugepages-${size}kB
Inside each of these directories, the same set of files will exist:
nr_hugepages
nr_overcommit_hugepages
free_hugepages
resv_hugepages
surplus_hugepages
which function as described above for the default hugepage-sized case.
If the user applications are going to request hugepages using mmap system
call, then it is required that system administrator mount a file system of
type hugetlbfs: