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92 lines
2.1 KiB
92 lines
2.1 KiB
4 months ago
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.TH statsnoop 8 "2016-02-08" "USER COMMANDS"
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.SH NAME
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statsnoop \- Trace stat() syscalls. Uses Linux eBPF/bcc.
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.SH SYNOPSIS
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.B statsnoop [\-h] [\-t] [\-x] [\-p PID]
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.SH DESCRIPTION
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statsnoop traces the different stat() syscalls, showing which processes are
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attempting to read information about which files. This can be useful for
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determining the location of config and log files, or for troubleshooting
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applications that are failing, especially on startup.
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This works by tracing various kernel sys_stat() functions using dynamic
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tracing, and will need updating to match any changes to these functions.
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This makes use of a Linux 4.5 feature (bpf_perf_event_output());
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for kernels older than 4.5, see the version under tools/old,
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which uses an older mechanism.
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Since this uses BPF, only the root user can use this tool.
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.SH REQUIREMENTS
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CONFIG_BPF and bcc.
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.SH OPTIONS
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.TP
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\-h
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Print usage message.
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.TP
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\-t
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Include a timestamp column: in seconds since the first event, with decimal
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places.
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.TP
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\-x
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Only print failed stats.
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.TP
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\-p PID
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Trace this process ID only (filtered in-kernel).
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.SH EXAMPLES
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.TP
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Trace all stat() syscalls:
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#
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.B statsnoop
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.TP
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Trace all stat() syscalls, and include timestamps:
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#
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.B statsnoop \-t
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.TP
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Trace only stat() syscalls that failed:
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#
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.B statsnoop \-x
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.TP
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Trace PID 181 only:
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#
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.B statsnoop \-p 181
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.SH FIELDS
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.TP
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TIME(s)
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Time of the call, in seconds.
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.TP
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PID
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Process ID
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.TP
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COMM
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Process name
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.TP
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FD
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File descriptor (if success), or -1 (if failed)
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.TP
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ERR
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Error number (see the system's errno.h)
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.TP
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PATH
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Open path
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.SH OVERHEAD
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This traces the kernel stat function and prints output for each event. As the
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rate of this is generally expected to be low (< 1000/s), the overhead is also
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expected to be negligible. If you have an application that is calling a high
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rate of stat()s, then test and understand overhead before use.
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.SH SOURCE
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This is from bcc.
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.IP
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https://github.com/iovisor/bcc
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.PP
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Also look in the bcc distribution for a companion _examples.txt file containing
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example usage, output, and commentary for this tool.
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.SH OS
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Linux
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.SH STABILITY
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Unstable - in development.
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.SH AUTHOR
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Brendan Gregg
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.SH SEE ALSO
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opensnoop(1)
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