Manual: syncsnoop-bpfcc

syncsnoop(8)					   System Manager's Manual					syncsnoop(8)

NAME
       syncsnoop - Trace sync() syscall. Uses Linux eBPF/bcc.

SYNOPSIS
       syncsnoop

DESCRIPTION
       syncsnoop traces calls to sync(), which flushes file system buffers to storage devices. These calls can cause perfor‐
       mance perturbations, and it can be useful to know if they are happening and how frequently.

       This  works  by	tracing	 the  kernel  sys_sync() function using dynamic tracing, and will need updating to match any
       changes to this function.

       This makes use of a Linux 4.4 feature (bpf_perf_event_output()); for kernels older than 4.4, see	 the  version  under
       tools/old, which uses an older mechanism.

       This program is also a basic example of eBPF/bcc.

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

REQUIREMENTS
       CONFIG_BPF and bcc.

EXAMPLES
       Trace calls to sync():
	      # syncsnoop

FIELDS
       TIME(s)
	      Time of the call, in seconds.

       CALL   Call traced.

OVERHEAD
       This  traces  the kernel sync function and prints output for each event. As the rate of this is generally expected to
       be low (<< 100/s), the overhead is also expected to be negligible.

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, original BCC Python version Tiago Ilieve, CO-RE version

SEE ALSO
       iostat(1)

USER COMMANDS						 2015-08-18						syncsnoop(8)