[PATCH] doc: describe swappiness more precisely

[Michal Hocko]

since fe35004f (mm: avoid swapping out with swappiness==0) reclaim
stopped swapping out anon pages completely when 0 value is used.
Although this is somehow expected it hasn't been done for a really long
time this way and so it is probably better to be explicit about the
effect.
While we are at it also mention the upper limit and its effect.

Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
---
 Documentation/sysctl/vm.txt |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 078701f..308fd77 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -640,6 +640,9 @@ 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.
+The value can be used from the [0, 100] range, where 0 means no swapping
+at all (even if there is a swap storage enabled) while 100 means that
+anonymous pages are reclaimed in the same rate as file pages.
 
 The default value is 60.
 
-- 
1.7.10.4

-- 
Michal Hocko
SUSE Labs
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