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-rw-r--r--Documentation/sysctl/vm.txt12
1 files changed, 8 insertions, 4 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index b606c2c4dd37..30289fab86eb 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -80,8 +80,10 @@ dirty_background_bytes
Contains the amount of dirty memory at which the pdflush background writeback
daemon will start writeback.
-If dirty_background_bytes is written, dirty_background_ratio becomes a function
-of its value (dirty_background_bytes / the amount of dirtyable system memory).
+Note: dirty_background_bytes is the counterpart of dirty_background_ratio. Only
+one of them may be specified at a time. When one sysctl is written it is
+immediately taken into account to evaluate the dirty memory limits and the
+other appears as 0 when read.
==============================================================
@@ -97,8 +99,10 @@ dirty_bytes
Contains the amount of dirty memory at which a process generating disk writes
will itself start writeback.
-If dirty_bytes is written, dirty_ratio becomes a function of its value
-(dirty_bytes / the amount of dirtyable system memory).
+Note: dirty_bytes is the counterpart of dirty_ratio. Only one of them may be
+specified at a time. When one sysctl is written it is immediately taken into
+account to evaluate the dirty memory limits and the other appears as 0 when
+read.
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