path: root/Documentation/sysctl
diff options
Diffstat (limited to 'Documentation/sysctl')
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 56dd29b97a9..5fdbb612aeb 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/vm:
- dirty_ratio
- dirty_writeback_centisecs
- drop_caches
+- extfrag_threshold
- hugepages_treat_as_movable
- hugetlb_shm_group
- laptop_mode
@@ -149,6 +150,20 @@ user should run `sync' first.
+This parameter affects whether the kernel will compact memory or direct
+reclaim to satisfy a high-order allocation. /proc/extfrag_index shows what
+the fragmentation index for each order is in each zone in the system. Values
+tending towards 0 imply allocations would fail due to lack of memory,
+values towards 1000 imply failures are due to fragmentation and -1 implies
+that the allocation will succeed as long as watermarks are met.
+The kernel will not compact memory in a zone if the
+fragmentation index is <= extfrag_threshold. The default value is 500.
This parameter is only useful when kernelcore= is specified at boot time to