nfs_inode_cache slab cache is very large

Issue

• slabtop shows the nfs_inode_cache slab cache is using a lot of memory:

$ slabtop -o
 Active / Total Objects (% used)    : 73324430 / 75887955 (96.6%)
 Active / Total Slabs (% used)      : 15671633 / 15671633 (100.0%)
 Active / Total Caches (% used)     : 110 / 159 (69.2%)
 Active / Total Size (% used)       : 48308948.60K / 48829118.25K (98.9%)
 Minimum / Average / Maximum Object : 0.02K / 0.64K / 128.00K

  OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME                   
41510835 41443838  99%    1.01K 13836945        3  55347780K nfs_inode_cache        
29346570 27616754  94%    0.21K 1630365       18   6521460K dentry_cache           
3770454 3288427  87%    0.06K  63906       59    255624K size-64                
450604 383965  85%    0.52K  64372        7    257488K radix_tree_node        
386280 196885  50%    0.09K   9657       40     38628K buffer_head            
215948 214254  99%    0.95K  53987        4    215948K ext4_inode_cache       
129750 119012  91%    0.12K   4325       30     17300K size-128               
 14415  14298  99%    0.25K    961       15      3844K size-256               
  9064   8957  98%    0.09K    206       44       824K sysfs_dir_cache        
  6292   4102  65%    0.17K    286       22      1144K vm_area_struct         
  4032   1404  34%    0.02K     28      144       112K anon_vma               
  3930   3841  97%    0.58K    655        6      2620K proc_inode_cache       
[...]

• How can we limit slab memory usage?
• I am concerned about the amount of memory consumed by slab. Can this impact available memory to my application?