5.2.26. /proc/slabinfo
This file gives full information about memory usage on the slab level. Linux kernels greater than version 2.2 use slab pools to manage memory above the page level. Commonly used objects have their own slab pools.
Instead of parsing the highly verbose
/proc/slabinfo file manually, the /usr/bin/slabtop program displays kernel slab cache information in real time. This program allows for custom configurations, including column sorting and screen refreshing.
A sample screen shot of
/usr/bin/slabtop usually looks like the following example:
Active / Total Objects (% used) : 133629 / 147300 (90.7%) Active / Total Slabs (% used) : 11492 / 11493 (100.0%) Active / Total Caches (% used) : 77 / 121 (63.6%) Active / Total Size (% used) : 41739.83K / 44081.89K (94.7%) Minimum / Average / Maximum Object : 0.01K / 0.30K / 128.00K OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME 44814 43159 96% 0.62K 7469 6 29876K ext3_inode_cache 36900 34614 93% 0.05K 492 75 1968K buffer_head 35213 33124 94% 0.16K 1531 23 6124K dentry_cache 7364 6463 87% 0.27K 526 14 2104K radix_tree_node 2585 1781 68% 0.08K 55 47 220K vm_area_struct 2263 2116 93% 0.12K 73 31 292K size-128 1904 1125 59% 0.03K 16 119 64K size-32 1666 768 46% 0.03K 14 119 56K anon_vma 1512 1482 98% 0.44K 168 9 672K inode_cache 1464 1040 71% 0.06K 24 61 96K size-64 1320 820 62% 0.19K 66 20 264K filp 678 587 86% 0.02K 3 226 12K dm_io 678 587 86% 0.02K 3 226 12K dm_tio 576 574 99% 0.47K 72 8 288K proc_inode_cache 528 514 97% 0.50K 66 8 264K size-512 492 372 75% 0.09K 12 41 48K bio 465 314 67% 0.25K 31 15 124K size-256 452 331 73% 0.02K 2 226 8K biovec-1 420 420 100% 0.19K 21 20 84K skbuff_head_cache 305 256 83% 0.06K 5 61 20K biovec-4 290 4 1% 0.01K 1 290 4K revoke_table 264 264 100% 4.00K 264 1 1056K size-4096 260 256 98% 0.19K 13 20 52K biovec-16 260 256 98% 0.75K 52 5 208K biovec-64
Some of the more commonly used statistics in
/proc/slabinfo that are included into /usr/bin/slabtop include:
OBJS— The total number of objects (memory blocks), including those in use (allocated), and some spares not in use.ACTIVE— The number of objects (memory blocks) that are in use (allocated).USE— Percentage of total objects that are active. ((ACTIVE/OBJS)(100))OBJ SIZE— The size of the objects.SLABS— The total number of slabs.OBJ/SLAB— The number of objects that fit into a slab.CACHE SIZE— The cache size of the slab.NAME— The name of the slab.
For more information on the
/usr/bin/slabtop program, refer to the slabtop man page.
