Display Linux kernel slab cache information in real time

Posted by Vivek Gite [Last updated: May 21, 2006]

Linux has tons of frequently used objects in the kernel such as buffer heads, inodes, dentries, etc. and have their own cache. The file /proc/slabinfo (less /proc/slabinfo) gives statistics. It is possible that slab cache information can be used to debug kernel problems (see crash command man page for more info).

slabtop command displays detailed kernel slab cache information in real time. It displays a listing of the top caches sorted by one of the listed sort criteria. It also displays a statistics header filled with slab layer information.

It generates output like vmtop perl script but in real time:

$ vmtop

VMTOP output:

Memory:    750.6 Mb      Free:   2.2%    Buffers:  56.1%   Cached:   3.1%
                       Active:  69.3%   Inactive:  24.0%
Lowmem:    750.6 Mb      Free:   2.2%       Slab:   3.0%   Memmap:   0.0%
                       Stacks:   0.1%       PMDs:   0.0%     PTEs:   0.3%

Top slabs:
      size-131072(dma)       0.1 Mb  (Active:      0.0 Mb,   0.0% full)
           size-131072       0.1 Mb  (Active:      0.0 Mb,   0.0% full)
       size-65536(dma)       0.1 Mb  (Active:      0.0 Mb,   0.0% full)
            size-65536       0.1 Mb  (Active:      0.0 Mb, 100.0% full)
       size-32768(dma)       0.0 Mb  (Active:      0.0 Mb,   0.0% full)

Now let us see output of slabtop command:

$ slabtop

slabtop command output: