Documentation/sysctl/vm.txt: clarify vfs_cache_pressure description

Existing description is worded in a way which almost encourages setting of
vfs_cache_pressure above 100, possibly way above it.

Users are left in a dark what this numeric value is - an int?  a
percentage?  what the scale is?

As a result, we are getting reports about noticeable performance
degradation from users who have set vfs_cache_pressure to ridiculously
high values - because they thought there is no downside to it.

Via code inspection it's obvious that this value is treated as a
percentage.  This patch changes text to reflect this fact, and adds a
cautionary paragraph advising against setting vfs_cache_pressure sky high.

Signed-off-by: Denys Vlasenko <[email protected]>
Cc: Alexander Viro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions