cachetop(8) System Manager's Manual cachetop(8)
NAME
cachetop - Statistics for linux page cache hit/miss ratios per
processes. Uses Linux eBPF/bcc.
SYNOPSIS
cachetop [-p PID] [interval]
DESCRIPTION
This traces four kernel functions and prints per-processes summaries
every interval seconds. This can be useful for processes workload char-
acterization, and looking for patterns in operation usage over time. It
provides a top-like interface which by default sorts by HITS in ascend-
ing order.
This works by tracing kernel page cache functions using dynamic trac-
ing, and will need updating to match any changes to these functions.
Edit the script to customize which functions are traced.
Since this uses BPF, only the root user can use this tool.
OPTIONS
-p PID Trace this PID only.
KEYBINDINGS
The following keybindings can be used to control the output of ca-
chetop.
< Use the previous column for sorting.
> Use the next column for sorting.
r Toggle sorting order (default ascending).
q Quit cachetop.
REQUIREMENTS
CONFIG_BPF and bcc.
EXAMPLES
Update summaries every five second:
# cachetop
Print summaries each second:
# cachetop 1
FIELDS
PID Process ID of the process causing the cache activity.
UID User ID of the process causing the cache activity.
CMD Name of the process.
HITS Number of page cache hits.
MISSES Number of page cache misses.
DIRTIES
Number of dirty pages added to the page cache.
READ_HIT%
Read hit percent of page cache usage.
WRITE_HIT%
Write hit percent of page cache usage.
BUFFERS_MB
Buffers size taken from /proc/meminfo.
CACHED_MB
Cached amount of data in current page cache taken from
/proc/meminfo.
OVERHEAD
This traces various kernel page cache functions and maintains in-kernel
counts, which are asynchronously copied to user-space. While the rate
of operations can be very high (>1G/sec) we can have up to 34% over-
head, this is still a relatively efficient way to trace these events,
and so the overhead is expected to be small for normal workloads. Mea-
sure in a test environment.
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
Emmanuel Bretelle, Rocky Xing
SEE ALSO
cachestat (8)
USER COMMANDS 2016-01-30 cachetop(8)
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