1 files changed, 7 insertions, 2 deletions

diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 5b6da0fb5fbf..bd4b34c03738 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -746,8 +746,8 @@ Changing this takes effect whenever an application requests memory.
 vfs_cache_pressure
 ------------------
 
-Controls the tendency of the kernel to reclaim the memory which is used for
-caching of directory and inode objects.
+This percentage value controls the tendency of the kernel to reclaim
+the memory which is used for caching of directory and inode objects.
 
 At the default value of vfs_cache_pressure=100 the kernel will attempt to
 reclaim dentries and inodes at a "fair" rate with respect to pagecache and
@@ -757,6 +757,11 @@ never reclaim dentries and inodes due to memory pressure and this can easily
 lead to out-of-memory conditions. Increasing vfs_cache_pressure beyond 100
 causes the kernel to prefer to reclaim dentries and inodes.
 
+Increasing vfs_cache_pressure significantly beyond 100 may have negative
+performance impact. Reclaim code needs to take various locks to find freeable
+directory and inode objects. With vfs_cache_pressure=1000, it will look for
+ten times more freeable objects than there are.
+
 ==============================================================
 
 zone_reclaim_mode: