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authorJustin Waters <justin.waters@timesys.com>2008-02-26 13:07:02 -0500
committerJustin Waters <justin.waters@timesys.com>2008-02-26 13:07:02 -0500
commitb80a32b9cc634adfa8eaef33ec981e7febf2ade2 (patch)
treef256bce13ba11f514a388160df84e1410bedbe2b /Documentation/sysctl/vm.txt
parent594133ef22fae0d737bd1b57352cf3f48a192c63 (diff)
Update the i.MX31 Kernel to 2.6.232.6.23-mx31ads-2008022618072.6.23-mx31-200802261807
This is the result of a brute-force attempt to update the kernel to 2.6.23. Now that we have a git tree, our effort will be a little nicer in the future. Signed-off-by: Justin Waters <justin.waters@timesys.com>
Diffstat (limited to 'Documentation/sysctl/vm.txt')
-rw-r--r--Documentation/sysctl/vm.txt63
1 files changed, 62 insertions, 1 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 1d192565e182..a0ccc5b60260 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -31,12 +31,15 @@ Currently, these files are in /proc/sys/vm:
- min_unmapped_ratio
- min_slab_ratio
- panic_on_oom
+- mmap_min_address
+- numa_zonelist_order
==============================================================
dirty_ratio, dirty_background_ratio, dirty_expire_centisecs,
dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode,
-block_dump, swap_token_timeout, drop-caches:
+block_dump, swap_token_timeout, drop-caches,
+hugepages_treat_as_movable:
See Documentation/filesystems/proc.txt
@@ -216,3 +219,61 @@ above-mentioned.
The default value is 0.
1 and 2 are for failover of clustering. Please select either
according to your policy of failover.
+
+==============================================================
+
+mmap_min_addr
+
+This file indicates the amount of address space which a user process will
+be restricted from mmaping. Since kernel null dereference bugs could
+accidentally operate based on the information in the first couple of pages
+of memory userspace processes should not be allowed to write to them. By
+default this value is set to 0 and no protections will be enforced by the
+security module. Setting this value to something like 64k will allow the
+vast majority of applications to work correctly and provide defense in depth
+against future potential kernel bugs.
+
+==============================================================
+
+numa_zonelist_order
+
+This sysctl is only for NUMA.
+'where the memory is allocated from' is controlled by zonelists.
+(This documentation ignores ZONE_HIGHMEM/ZONE_DMA32 for simple explanation.
+ you may be able to read ZONE_DMA as ZONE_DMA32...)
+
+In non-NUMA case, a zonelist for GFP_KERNEL is ordered as following.
+ZONE_NORMAL -> ZONE_DMA
+This means that a memory allocation request for GFP_KERNEL will
+get memory from ZONE_DMA only when ZONE_NORMAL is not available.
+
+In NUMA case, you can think of following 2 types of order.
+Assume 2 node NUMA and below is zonelist of Node(0)'s GFP_KERNEL
+
+(A) Node(0) ZONE_NORMAL -> Node(0) ZONE_DMA -> Node(1) ZONE_NORMAL
+(B) Node(0) ZONE_NORMAL -> Node(1) ZONE_NORMAL -> Node(0) ZONE_DMA.
+
+Type(A) offers the best locality for processes on Node(0), but ZONE_DMA
+will be used before ZONE_NORMAL exhaustion. This increases possibility of
+out-of-memory(OOM) of ZONE_DMA because ZONE_DMA is tend to be small.
+
+Type(B) cannot offer the best locality but is more robust against OOM of
+the DMA zone.
+
+Type(A) is called as "Node" order. Type (B) is "Zone" order.
+
+"Node order" orders the zonelists by node, then by zone within each node.
+Specify "[Nn]ode" for zone order
+
+"Zone Order" orders the zonelists by zone type, then by node within each
+zone. Specify "[Zz]one"for zode order.
+
+Specify "[Dd]efault" to request automatic configuration. Autoconfiguration
+will select "node" order in following case.
+(1) if the DMA zone does not exist or
+(2) if the DMA zone comprises greater than 50% of the available memory or
+(3) if any node's DMA zone comprises greater than 60% of its local memory and
+ the amount of local memory is big enough.
+
+Otherwise, "zone" order will be selected. Default order is recommended unless
+this is causing problems for your system/application.