PERF-INJECT(1) perf Manual PERF-INJECT(1)
NAME
perf-inject - Filter to augment the events stream with additional
information
SYNOPSIS
perf inject <options>
DESCRIPTION
perf-inject reads a perf-record event stream and repipes it to stdout.
At any point the processing code can inject other events into the event
stream - in this case build-ids (-b option) are read and injected as
needed into the event stream.
Build-ids are just the first user of perf-inject - potentially anything
that needs userspace processing to augment the events stream with
additional information could make use of this facility.
OPTIONS
-b, --build-ids
Inject build-ids of DSOs hit by samples into the output stream.
This means it needs to process all SAMPLE records to find the DSOs.
--buildid-all
Inject build-ids of all DSOs into the output stream regardless of
hits and skip SAMPLE processing.
--known-build-ids=
Override build-ids to inject using these comma-separated pairs of
build-id and path. Understands file://filename to read these pairs
from a file, which can be generated with perf buildid-list.
-v, --verbose
Be more verbose.
-i, --input=
Input file name. (default: stdin)
-o, --output=
Output file name. (default: stdout)
-s, --sched-stat
Merge sched_stat and sched_switch for getting events where and how
long tasks slept. sched_switch contains a callchain where a task
slept and sched_stat contains a timeslice how long a task slept.
-k, --vmlinux=<file>
vmlinux pathname
--ignore-vmlinux
Ignore vmlinux files.
--kallsyms=<file>
kallsyms pathname
--itrace
Decode Instruction Tracing data, replacing it with synthesized
events. Options are:
i synthesize instructions events
y synthesize cycles events
b synthesize branches events (branch misses for Arm SPE)
c synthesize branches events (calls only)
r synthesize branches events (returns only)
x synthesize transactions events
w synthesize ptwrite events
p synthesize power events (incl. PSB events for Intel PT)
o synthesize other events recorded due to the use
of aux-output (refer to perf record)
I synthesize interrupt or similar (asynchronous) events
(e.g. Intel PT Event Trace)
e synthesize error events
d create a debug log
f synthesize first level cache events
m synthesize last level cache events
M synthesize memory events
t synthesize TLB events
a synthesize remote access events
g synthesize a call chain (use with i or x)
G synthesize a call chain on existing event records
l synthesize last branch entries (use with i or x)
L synthesize last branch entries on existing event records
s skip initial number of events
q quicker (less detailed) decoding
A approximate IPC
Z prefer to ignore timestamps (so-called "timeless" decoding)
T use the timestamp trace as kernel time
The default is all events i.e. the same as --itrace=iybxwpe,
except for perf script where it is --itrace=ce
In addition, the period (default 100000, except for perf script where it is 1)
for instructions events can be specified in units of:
i instructions
t ticks
ms milliseconds
us microseconds
ns nanoseconds (default)
Also the call chain size (default 16, max. 1024) for instructions or
transactions events can be specified.
Also the number of last branch entries (default 64, max. 1024) for
instructions or transactions events can be specified.
Similar to options g and l, size may also be specified for options G and L.
On x86, note that G and L work poorly when data has been recorded with
large PEBS. Refer linkperf:perf-intel-pt[1] man page for details.
It is also possible to skip events generated (instructions, branches, transactions,
ptwrite, power) at the beginning. This is useful to ignore initialization code.
--itrace=i0nss1000000
skips the first million instructions.
The 'e' option may be followed by flags which affect what errors will or
will not be reported. Each flag must be preceded by either '+' or '-'.
The flags are:
o overflow
l trace data lost
If supported, the 'd' option may be followed by flags which affect what
debug messages will or will not be logged. Each flag must be preceded
by either '+' or '-'. The flags are:
a all perf events
e output only on errors (size configurable - see linkperf:perf-config[1])
o output to stdout
If supported, the 'q' option may be repeated to increase the effect.
--strip
Use with --itrace to strip out non-synthesized events.
-j, --jit
Process jitdump files by injecting the mmap records corresponding
to jitted functions. This option also generates the ELF images for
each jitted function found in the jitdumps files captured in the
input perf.data file. Use this option if you are monitoring
environment using JIT runtimes, such as Java, DART or V8.
-f, --force
Don’t complain, do it.
--vm-time-correlation[=OPTIONS]
Some architectures may capture AUX area data which contains
timestamps affected by virtualization. This option will update
those timestamps in place, to correlate with host timestamps. The
in-place update means that an output file is not specified, and
instead the input file is modified. The options are architecture
specific, except that they may start with "dry-run" which will
cause the file to be processed but without updating it. Currently
this option is supported only by Intel PT, refer perf-intel-pt(1)
--guest-data=<path>,<pid>[,<time offset>[,<time scale>]]
Insert events from a perf.data file recorded in a virtual machine
at the same time as the input perf.data file was recorded on the
host. The Process ID (PID) of the QEMU hypervisor process must be
provided, and the time offset and time scale (multiplier) will
likely be needed to convert guest time stamps into host time
stamps. For example, for x86 the TSC Offset and Multiplier could be
provided for a virtual machine using Linux command line option
no-kvmclock. Currently only mmap, mmap2, comm, task,
context_switch, ksymbol, and text_poke events are inserted, as well
as build ID information. The QEMU option -name debug-threads=on is
needed so that thread names can be used to determine which thread
is running which VCPU. Note libvirt seems to use this by default.
When using perf record in the guest, option --sample-identifier
should be used, and also --buildid-all and --switch-events may be
useful.
--guestmount=<path>
Guest OS root file system mount directory. Users mount guest OS
root directories under <path> by a specific filesystem access
method, typically, sshfs. For example, start 2 guest OS, one’s pid
is 8888 and the other’s is 9999:
$ mkdir ~/guestmount
$ cd ~/guestmount
$ sshfs -o allow_other,direct_io -p 5551 localhost:/ 8888/
$ sshfs -o allow_other,direct_io -p 5552 localhost:/ 9999/
$ perf inject --guestmount=~/guestmount
SEE ALSO
perf-record(1), perf-report(1), perf-archive(1), perf-intel-pt(1)
perf 11/18/2025 PERF-INJECT(1)
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