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-rw-r--r--Documentation/sysctl/vm.txt25
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 6c7d18c53f84..5fdbb612aeb8 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -19,6 +19,7 @@ files can be found in mm/swap.c.
Currently, these files are in /proc/sys/vm:
- block_dump
+- compact_memory
- dirty_background_bytes
- dirty_background_ratio
- dirty_bytes
@@ -26,6 +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
@@ -64,6 +66,15 @@ information on block I/O debugging is in Documentation/laptops/laptop-mode.txt.
==============================================================
+compact_memory
+
+Available only when CONFIG_COMPACTION is set. When 1 is written to the file,
+all zones are compacted such that free memory is available in contiguous
+blocks where possible. This can be important for example in the allocation of
+huge pages although processes will also directly compact memory as required.
+
+==============================================================
+
dirty_background_bytes
Contains the amount of dirty memory at which the pdflush background writeback
@@ -139,6 +150,20 @@ user should run `sync' first.
==============================================================
+extfrag_threshold
+
+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.
+
+==============================================================
+
hugepages_treat_as_movable
This parameter is only useful when kernelcore= is specified at boot time to