You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
54 lines
1.6 KiB
54 lines
1.6 KiB
.TH vfscount 8 "2015-08-18" "USER COMMANDS" |
|
.SH NAME |
|
vfscount \- Count VFS calls ("vfs_*"). Uses Linux eBPF/bcc. |
|
.SH SYNOPSIS |
|
.B vfscount |
|
.SH DESCRIPTION |
|
This counts VFS calls. This can be useful for general workload |
|
characterization of these operations. |
|
|
|
This works by tracing all kernel functions beginning with "vfs_" using dynamic |
|
tracing. This may match more functions than you are interested in measuring: |
|
Edit the script to customize which functions to trace. |
|
|
|
Since this uses BPF, only the root user can use this tool. |
|
.SH REQUIREMENTS |
|
CONFIG_BPF and bcc. |
|
.SH EXAMPLES |
|
.TP |
|
Count some VFS calls until Ctrl-C is hit: |
|
# |
|
.B vfscount |
|
.SH FIELDS |
|
.TP |
|
ADDR |
|
Address of the instruction pointer that was traced (only useful if the FUNC column is suspicious and you would like to double check the translation). |
|
.TP |
|
FUNC |
|
Kernel function name |
|
.TP |
|
COUNT |
|
Number of calls while tracing |
|
.SH OVERHEAD |
|
This traces kernel vfs functions and maintains in-kernel counts, which |
|
are asynchronously copied to user-space. While the rate of VFS operations can |
|
be very high (>1M/sec), this is 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, and if overheads are an issue, edit the script |
|
to reduce the types of vfs functions traced (currently all beginning with |
|
"vfs_"). |
|
.SH SOURCE |
|
This is from bcc. |
|
.IP |
|
https://github.com/iovisor/bcc |
|
.PP |
|
Also look in the bcc distribution for a companion _examples.txt file containing |
|
example usage, output, and commentary for this tool. |
|
.SH OS |
|
Linux |
|
.SH STABILITY |
|
Unstable - in development. |
|
.SH AUTHOR |
|
Brendan Gregg |
|
.SH SEE ALSO |
|
vfsstat(8)
|
|
|