mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical

[sfrench/cifs-2.6.git] / Documentation / sysctl / vm.txt

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 48244c42ff5214176cf4dfc071f803e2aa8cd71f..30fd16b141968dccfc216f55343bbfd6dc21b245 100644 (file)
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -157,6 +157,10 @@ Note: the minimum value allowed for dirty_bytes is two pages (in bytes); any
 value lower than this limit will be ignored and the old configuration will be
 retained.
 
+Note: the value of dirty_bytes also must be set greater than
+dirty_background_bytes or the amount of memory corresponding to
+dirty_background_ratio.
+
 ==============================================================
 
 dirty_expire_centisecs
@@ -176,6 +180,9 @@ generating disk writes will itself start writing out dirty data.
 
 The total available memory is not equal to total system memory.
 
+Note: dirty_ratio must be set greater than dirty_background_ratio or
+ratio corresponding to dirty_background_bytes.
+
 ==============================================================
 
 dirty_writeback_centisecs
@@ -572,7 +579,9 @@ See Documentation/nommu-mmap.txt for more information.
 
 numa_zonelist_order
 
-This sysctl is only for NUMA.
+This sysctl is only for NUMA and it is deprecated. Anything but
+Node order will fail!
+
 '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...)