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66 lines
1.8 KiB
66 lines
1.8 KiB
4 months ago
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.TH vfsstat 8 "2015-08-18" "USER COMMANDS"
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.SH NAME
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vfsstat \- Statistics for some common VFS calls. Uses Linux eBPF/bcc.
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.SH SYNOPSIS
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.B vfsstat
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[interval [count]]
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.SH DESCRIPTION
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This traces some common VFS calls and prints per-second summaries. This can
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be useful for general workload characterization, and looking for patterns
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in operation usage over time.
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This works by tracing some kernel vfs functions using dynamic tracing, and will
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need updating to match any changes to these functions. Edit the script to
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customize which functions are traced. Also see vfscount, which is more
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easily customized to trace multiple functions.
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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 EXAMPLES
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.TP
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Print summaries each second:
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#
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.B vfsstat
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.TP
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Print output every five seconds, three times:
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#
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.B vfsstat 5 3
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.SH FIELDS
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.TP
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READ/s
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Number of vfs_read() calls as a per-second average.
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.TP
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WRITE/s
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Number of vfs_write() calls as a per-second average.
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.TP
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CREATE/s
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Number of vfs_create() calls as a per-second average.
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.TP
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OPEN/s
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Number of vfs_open() calls as a per-second average.
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.TP
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FSYNC/s
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Number of vfs_fsync() calls as a per-second average.
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.SH OVERHEAD
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This traces various kernel vfs functions and maintains in-kernel counts, which
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are asynchronously copied to user-space. While the rate of VFS operations can
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be very high (>1M/sec), this is a relatively efficient way to trace these
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events, and so the overhead is expected to be small for normal workloads.
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Measure in a test environment.
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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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vfscount(8)
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