diff options
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/hugetlbpage.txt | 25 | ||||
| -rw-r--r-- | Documentation/vm/soft-dirty.txt | 7 |
2 files changed, 19 insertions, 13 deletions
diff --git a/Documentation/vm/hugetlbpage.txt b/Documentation/vm/hugetlbpage.txt index 4ac359b7aa1..bdd4bb97fff 100644 --- a/Documentation/vm/hugetlbpage.txt +++ b/Documentation/vm/hugetlbpage.txt @@ -165,6 +165,7 @@ which function as described above for the default huge page-sized case. Interaction of Task Memory Policy with Huge Page Allocation/Freeing +=================================================================== Whether huge pages are allocated and freed via the /proc interface or the /sysfs interface using the nr_hugepages_mempolicy attribute, the NUMA @@ -229,6 +230,7 @@ resulting effect on persistent huge page allocation is as follows: of huge pages over all on-lines nodes with memory. Per Node Hugepages Attributes +============================= A subset of the contents of the root huge page control directory in sysfs, described above, will be replicated under each the system device of each @@ -258,6 +260,7 @@ applied, from which node the huge page allocation will be attempted. Using Huge Pages +================ If the user applications are going to request huge pages using mmap system call, then it is required that system administrator mount a file system of @@ -296,20 +299,16 @@ calls, though the mount of filesystem will be required for using mmap calls without MAP_HUGETLB. For an example of how to use mmap with MAP_HUGETLB see map_hugetlb.c. -******************************************************************* +Examples +======== -/* - * map_hugetlb: see tools/testing/selftests/vm/map_hugetlb.c - */ +1) map_hugetlb: see tools/testing/selftests/vm/map_hugetlb.c -******************************************************************* +2) hugepage-shm: see tools/testing/selftests/vm/hugepage-shm.c -/* - * hugepage-shm: see tools/testing/selftests/vm/hugepage-shm.c - */ +3) hugepage-mmap: see tools/testing/selftests/vm/hugepage-mmap.c -******************************************************************* - -/* - * hugepage-mmap: see tools/testing/selftests/vm/hugepage-mmap.c - */ +4) The libhugetlbfs (http://libhugetlbfs.sourceforge.net) library provides a + wide range of userspace tools to help with huge page usability, environment + setup, and control. Furthermore it provides useful test cases that should be + used when modifying code to ensure no regressions are introduced. diff --git a/Documentation/vm/soft-dirty.txt b/Documentation/vm/soft-dirty.txt index 9a12a5956bc..55684d11a1e 100644 --- a/Documentation/vm/soft-dirty.txt +++ b/Documentation/vm/soft-dirty.txt @@ -28,6 +28,13 @@ This is so, since the pages are still mapped to physical memory, and thus all the kernel does is finds this fact out and puts both writable and soft-dirty bits on the PTE. + While in most cases tracking memory changes by #PF-s is more than enough +there is still a scenario when we can lose soft dirty bits -- a task +unmaps a previously mapped memory region and then maps a new one at exactly +the same place. When unmap is called, the kernel internally clears PTE values +including soft dirty bits. To notify user space application about such +memory region renewal the kernel always marks new memory regions (and +expanded regions) as soft dirty. This feature is actively used by the checkpoint-restore project. You can find more details about it on http://criu.org |