|
HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
PERF-LIST(1) perf Manual PERF-LIST(1)
perf-list - List all symbolic event types
perf list [<options>]
[hw|sw|cache|tracepoint|pmu|sdt|metric|metricgroup|event_glob]
This command displays the symbolic event types which can be
selected in the various perf commands with the -e option.
-d, --desc
Print extra event descriptions. (default)
--no-desc
Don’t print descriptions.
-v, --long-desc
Print longer event descriptions.
--debug
Enable debugging output.
--details
Print how named events are resolved internally into perf
events, and also any extra expressions computed by perf stat.
--deprecated
Print deprecated events. By default the deprecated events are
hidden.
--unit
Print PMU events and metrics limited to the specific PMU name.
(e.g. --unit cpu, --unit msr, --unit cpu_core, --unit
cpu_atom)
-j, --json
Output in JSON format.
-o, --output=
Output file name. By default output is written to stdout.
Events can optionally have a modifier by appending a colon and one
or more modifiers. Modifiers allow the user to restrict the events
to be counted. The following modifiers exist:
u - user-space counting
k - kernel counting
h - hypervisor counting
I - non idle counting
G - guest counting (in KVM guests)
H - host counting (not in KVM guests)
p - precise level
P - use maximum detected precise level
S - read sample value (PERF_SAMPLE_READ)
D - pin the event to the PMU
W - group is weak and will fallback to non-group if not schedulable,
e - group or event are exclusive and do not share the PMU
b - use BPF aggregration (see perf stat --bpf-counters)
R - retire latency value of the event
The p modifier can be used for specifying how precise the
instruction address should be. The p modifier can be specified
multiple times:
0 - SAMPLE_IP can have arbitrary skid
1 - SAMPLE_IP must have constant skid
2 - SAMPLE_IP requested to have 0 skid
3 - SAMPLE_IP must have 0 skid, or uses randomization to avoid
sample shadowing effects.
For Intel systems precise event sampling is implemented with PEBS
which supports up to precise-level 2, and precise level 3 for some
special cases
On AMD systems it is implemented using IBS OP (up to precise-level
2). Unlike Intel PEBS which provides levels of precision, AMD core
pmu is inherently non-precise and IBS is inherently precise. (i.e.
ibs_op//, ibs_op//p, ibs_op//pp and ibs_op//ppp are all same). The
precise modifier works with event types 0x76 (cpu-cycles, CPU
clocks not halted) and 0xC1 (micro-ops retired). Both events map
to IBS execution sampling (IBS op) with the IBS Op Counter Control
bit (IbsOpCntCtl) set respectively (see the Core Complex (CCX) →
Processor x86 Core → Instruction Based Sampling (IBS) section of
the [AMD Processor Programming Reference (PPR)] relevant to the
family, model and stepping of the processor being used).
Manual Volume 2: System Programming, 13.3 Instruction-Based
Sampling). Examples to use IBS:
perf record -a -e cpu-cycles:p ... # use ibs op counting cycles
perf record -a -e r076:p ... # same as -e cpu-cycles:p
perf record -a -e r0C1:p ... # use ibs op counting micro-ops
Even when an event is not available in a symbolic form within perf
right now, it can be encoded in a per processor specific way.
For instance on x86 CPUs, N is a hexadecimal value that represents
the raw register encoding with the layout of IA32_PERFEVTSELx MSRs
(see [Intel® 64 and IA-32 Architectures Software Developer’s
Manual Volume 3B: System Programming Guide] Figure 30-1 Layout of
IA32_PERFEVTSELx MSRs) or AMD’s PERF_CTL MSRs (see the Core
Complex (CCX) → Processor x86 Core → MSR Registers section of the
[AMD Processor Programming Reference (PPR)] relevant to the
family, model and stepping of the processor being used).
Note: Only the following bit fields can be set in x86 counter
registers: event, umask, edge, inv, cmask. Esp. guest/host only
and OS/user mode flags must be setup using EVENT MODIFIERS.
Example:
If the Intel docs for a QM720 Core i7 describe an event as:
Event Umask Event Mask
Num. Value Mnemonic Description Comment
A8H 01H LSD.UOPS Counts the number of micro-ops Use cmask=1 and
delivered by loop stream detector invert to count
cycles
raw encoding of 0x1A8 can be used:
perf stat -e r1a8 -a sleep 1
perf record -e r1a8 ...
It’s also possible to use pmu syntax:
perf record -e r1a8 -a sleep 1
perf record -e cpu/r1a8/ ...
perf record -e cpu/r0x1a8/ ...
Some processors, like those from AMD, support event codes and unit
masks larger than a byte. In such cases, the bits corresponding to
the event configuration parameters can be seen with:
cat /sys/bus/event_source/devices/<pmu>/format/<config>
Example:
If the AMD docs for an EPYC 7713 processor describe an event as:
Event Umask Event Mask
Num. Value Mnemonic Description
28FH 03H op_cache_hit_miss.op_cache_hit Counts Op Cache micro-tag
hit events.
raw encoding of 0x0328F cannot be used since the upper nibble of
the EventSelect bits have to be specified via bits 32-35 as can be
seen with:
cat /sys/bus/event_source/devices/cpu/format/event
raw encoding of 0x20000038F should be used instead:
perf stat -e r20000038f -a sleep 1
perf record -e r20000038f ...
It’s also possible to use pmu syntax:
perf record -e r20000038f -a sleep 1
perf record -e cpu/r20000038f/ ...
perf record -e cpu/r0x20000038f/ ...
You should refer to the processor specific documentation for
getting these details. Some of them are referenced in the SEE ALSO
section below.
perf also supports an extended syntax for specifying raw
parameters to PMUs. Using this typically requires looking up the
specific event in the CPU vendor specific documentation.
The available PMUs and their raw parameters can be listed with
ls /sys/devices/*/format
For example the raw event "LSD.UOPS" core pmu event above could be
specified as
perf stat -e cpu/event=0xa8,umask=0x1,name=LSD.UOPS_CYCLES,cmask=0x1/ ...
or using extended name syntax
perf stat -e cpu/event=0xa8,umask=0x1,cmask=0x1,name=\'LSD.UOPS_CYCLES:cmask=0x1\'/ ...
Some PMUs are not associated with a core, but with a whole CPU
socket. Events on these PMUs generally cannot be sampled, but only
counted globally with perf stat -a. They can be bound to one
logical CPU, but will measure all the CPUs in the same socket.
This example measures memory bandwidth every second on the first
memory controller on socket 0 of a Intel Xeon system
perf stat -C 0 -a uncore_imc_0/cas_count_read/,uncore_imc_0/cas_count_write/ -I 1000 ...
Each memory controller has its own PMU. Measuring the complete
system bandwidth would require specifying all imc PMUs (see perf
list output), and adding the values together. To simplify creation
of multiple events, prefix and glob matching is supported in the
PMU name, and the prefix uncore_ is also ignored when performing
the match. So the command above can be expanded to all memory
controllers by using the syntaxes:
perf stat -C 0 -a imc/cas_count_read/,imc/cas_count_write/ -I 1000 ...
perf stat -C 0 -a *imc*/cas_count_read/,*imc*/cas_count_write/ -I 1000 ...
This example measures the combined core power every second
perf stat -I 1000 -e power/energy-cores/ -a
For non root users generally only context switched PMU events are
available. This is normally only the events in the cpu PMU, the
predefined events like cycles and instructions and some software
events.
Other PMUs and global measurements are normally root only. Some
event qualifiers, such as "any", are also root only.
This can be overridden by setting the kernel.perf_event_paranoid
sysctl to -1, which allows non root to use these events.
For accessing trace point events perf needs to have read access to
/sys/kernel/tracing, even when perf_event_paranoid is in a relaxed
setting.
Some events don’t have an associated PMU instead reading values
available to software without perf_event_open. As these events
don’t support sampling they can only really be read by tools like
perf stat.
Tool events provide times and certain system parameters. Examples
include duration_time, user_time, system_time and num_cpus_online.
Hwmon events provide easy access to hwmon sysfs data typically in
/sys/class/hwmon. This information includes temperatures, fan
speeds and energy usage.
Some PMUs control advanced hardware tracing capabilities, such as
Intel PT, that allows low overhead execution tracing. These are
described in a separate intel-pt.txt document.
Some pmu events listed by perf-list will be displayed with ? in
them. For example:
hv_gpci/dtbp_ptitc,phys_processor_idx=?/
This means that when provided as an event, a value for ? must also
be supplied. For example:
perf stat -C 0 -e 'hv_gpci/dtbp_ptitc,phys_processor_idx=0x2/' ...
EVENT QUALIFIERS:
It is also possible to add extra qualifiers to an event:
percore:
Sums up the event counts for all hardware threads in a core, e.g.:
perf stat -e cpu/event=0,umask=0x3,percore=1/
Perf supports time based multiplexing of events, when the number
of events active exceeds the number of hardware performance
counters. Multiplexing can cause measurement errors when the
workload changes its execution profile.
When metrics are computed using formulas from event counts, it is
useful to ensure some events are always measured together as a
group to minimize multiplexing errors. Event groups can be
specified using { }.
perf stat -e '{instructions,cycles}' ...
The number of available performance counters depend on the CPU. A
group cannot contain more events than available counters. For
example Intel Core CPUs typically have four generic performance
counters for the core, plus three fixed counters for instructions,
cycles and ref-cycles. Some special events have restrictions on
which counter they can schedule, and may not support multiple
instances in a single group. When too many events are specified in
the group some of them will not be measured.
Globally pinned events can limit the number of counters available
for other groups. On x86 systems, the NMI watchdog pins a counter
by default. The nmi watchdog can be disabled as root with
echo 0 > /proc/sys/kernel/nmi_watchdog
Events from multiple different PMUs cannot be mixed in a group,
with some exceptions for software events.
perf also supports group leader sampling using the :S specifier.
perf record -e '{cycles,instructions}:S' ...
perf report --group
Normally all events in an event group sample, but with :S only the
first event (the leader) samples, and it only reads the values of
the other events in the group.
However, in the case AUX area events (e.g. Intel PT or CoreSight),
the AUX area event must be the leader, so then the second event
samples, not the first.
Without options all known events will be listed.
To limit the list use:
1. hw or hardware to list hardware events such as cache-misses,
etc.
2. sw or software to list software events such as context
switches, etc.
3. cache or hwcache to list hardware cache events such as
L1-dcache-loads, etc.
4. tracepoint to list all tracepoint events, alternatively use
subsys_glob:event_glob to filter by tracepoint subsystems such
as sched, block, etc.
5. pmu to print the kernel supplied PMU events.
6. sdt to list all Statically Defined Tracepoint events.
7. metric to list metrics
8. metricgroup to list metricgroups with metrics.
9. If none of the above is matched, it will apply the supplied
glob to all events, printing the ones that match.
10. As a last resort, it will do a substring search in all event
names.
One or more types can be used at the same time, listing the events
for the types specified.
Support raw format:
1. --raw-dump, shows the raw-dump of all the events.
2. --raw-dump [hw|sw|cache|tracepoint|pmu|event_glob], shows the
raw-dump of a certain kind of events.
perf-stat(1), perf-top(1), perf-record(1), Intel® 64 and IA-32
Architectures Software Developer’s Manual Volume 3B: System
Programming Guide[1], AMD Processor Programming Reference (PPR)[2]
1. Intel® 64 and IA-32 Architectures Software Developer’s Manual
Volume 3B: System Programming Guide
http://www.intel.com/sdm/
2. AMD Processor Programming Reference (PPR)
https://bugzilla.kernel.org/show_bug.cgi?id=206537
This page is part of the perf (Performance analysis tools for
Linux (in Linux source tree)) project. Information about the
project can be found at
⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩. If you have a
bug report for this manual page, send it to
linux-kernel@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩
on 2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2025-02-01.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to man-pages@man7.org
perf 2024-11-09 PERF-LIST(1)
Pages that refer to this page: perf(1), perf-evlist(1), perf-record(1), perf-stat(1), perf-top(1)
|
HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|