Prior to upstream commit fe35004f ("[mm] avoid swapping out
with swappiness==0") setting swappiness to 0, reclaim code
could still evict recently used user anonymous memory to swap
even though there is a significant amount of RAM used for page
cache.
The behaviour of setting swappiness to 0 has since changed.
When set, the reclaim code does not initiate swap until the
amount of free pages and file-backed pages, is less than the
high water mark in a zone.
Let's update the documentation to reflect this.
Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Acked-by: Bryn M. Reeves <bmr@xxxxxxxxxx>
---
Documentation/sysctl/vm.txt | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 9f5481b..38388ee 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -696,7 +696,9 @@ swappiness
This control is used to define how aggressive the kernel will swap
memory pages. Higher values will increase agressiveness, lower values
-decrease the amount of swap.
+decrease the amount of swap. A value of 0 instructs the kernel not to
+initiate swap until the amount of free and file-backed pages, is less
+than the high water mark in a zone.
The default value is 60.
--
1.8.4.2
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