Section 8 · System administration

bcc-slabratetop.8

Package: bcc-tools

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slabratetop

NAME
SYNOPSIS
DESCRIPTION
REQUIREMENTS
OPTIONS
EXAMPLES
FIELDS
OVERHEAD
SOURCE
OS
STABILITY
AUTHOR
SEE ALSO

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

STABILITY

Unstable - in development.

AUTHOR

Brendan Gregg