NAME¶

slabratetop - Kernel SLAB/SLUB memory cache allocation rate top. Uses Linux BPF/bcc.

SYNOPSIS¶

slabratetop [-h] [-C] [-r MAXROWS] [interval] [count]

DESCRIPTION¶

This is top for the the rate of kernel SLAB/SLUB memory allocations. It works by tracing kmem_cache_alloc() calls, a commonly used interface for kernel memory allocation (SLAB or SLUB). It summarizes the rate and total bytes allocated of these calls per interval: the activity. Compare this to slabtop(1), which shows the current static volume of the caches.

This tool uses kernel dynamic tracing of the kmem_cache_alloc() function.

Since this uses BPF, only the root user can use this tool.

REQUIREMENTS¶

CONFIG_BPF and bcc.

OPTIONS¶

-C

Don't clear the screen.

-r MAXROWS

Maximum number of rows to print. Default is 20.

interval

Interval between updates, seconds.

count

Number of interval summaries.

EXAMPLES¶

Summarize active kernel SLAB/SLUB calls (kmem_cache_alloc()), showing the top 20 caches every second:

# slabratetop

Don't clear the screen, and top 8 rows only:

# slabratetop -Cr 8

5 second summaries, 10 times only:

# slabratetop 5 10

FIELDS¶

loadavg:

The contents of /proc/loadavg

CACHE

Kernel cache name.

ALLOCS

Allocations (number of calls).

BYTES

Total bytes allocated.

OVERHEAD¶

If kmem_cache_alloc() is called at a high rate (eg, >100k/second) the overhead of this tool might begin to be measurable. The rate can be seen in the ALLOCS column of the output.

SOURCE¶

This is from bcc.

https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.

OS¶

Linux

AUTHOR¶

Brendan Gregg

SEE ALSO¶

slabtop(1)