Manual: cachetop-bpfcc

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 characterization, and looking for patterns in operation usage over time. It  provides	 a  top-like
       interface which by default sorts by HITS in ascending order.

       This  works by tracing kernel page cache functions using dynamic tracing, 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 cachetop.

       <      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% overhead, this is still a
       relatively efficient way to trace these events, and so the overhead is expected to be  small  for  normal  workloads.
       Measure 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)