Events
Perf is an event-oriented observability tool, so first let's take a look available events
List events
All events
perf listto show all event current perf supports.
branch-instructions OR branches [Hardware event]
branch-misses [Hardware event]
bus-cycles [Hardware event]
cache-misses [Hardware event]
cache-references [Hardware event]
cpu-cycles OR cycles [Hardware event]
instructions [Hardware event]
ref-cycles [Hardware event]
alignment-faults [Software event]
bpf-output [Software event]
context-switches OR cs [Software event]
cpu-clock [Software event]
cpu-migrations OR migrations [Software event]
dummy [Software event]
emulation-faults [Software event]
major-faults [Software event]
minor-faults [Software event]
page-faults OR faults [Software event]
task-clock [Software event]
L1-dcache-load-misses [Hardware cache event]
L1-dcache-loads [Hardware cache event]
L1-dcache-stores [Hardware cache event]
L1-icache-load-misses [Hardware cache event]
LLC-load-misses [Hardware cache event]
LLC-loads [Hardware cache event]
LLC-store-misses [Hardware cache event]
LLC-stores [Hardware cache event]
branch-load-misses [Hardware cache event]
branch-loads [Hardware cache event]
dTLB-load-misses [Hardware cache event]
dTLB-loads [Hardware cache event]
dTLB-store-misses [Hardware cache event]
dTLB-stores [Hardware cache event]
iTLB-load-misses [Hardware cache event]
iTLB-loads [Hardware cache event]
node-load-misses [Hardware cache event]
node-loads [Hardware cache event]
node-store-misses [Hardware cache event]
node-stores [Hardware cache event]
branch-instructions OR cpu/branch-instructions/ [Kernel PMU event]
branch-misses OR cpu/branch-misses/ [Kernel PMU event]
bus-cycles OR cpu/bus-cycles/ [Kernel PMU event]
cache-misses OR cpu/cache-misses/ [Kernel PMU event]
cache-references OR cpu/cache-references/ [Kernel PMU event]
cpu-cycles OR cpu/cpu-cycles/ [Kernel PMU event]
cstate_core/c3-residency/ [Kernel PMU event]
cstate_core/c6-residency/ [Kernel PMU event]
cstate_core/c7-residency/ [Kernel PMU event]
cstate_pkg/c2-residency/ [Kernel PMU event]
cstate_pkg/c3-residency/ [Kernel PMU event]
cstate_pkg/c6-residency/ [Kernel PMU event]
cstate_pkg/c7-residency/ [Kernel PMU event]
cycles-ct OR cpu/cycles-ct/ [Kernel PMU event]
cycles-t OR cpu/cycles-t/ [Kernel PMU event]
el-abort OR cpu/el-abort/ [Kernel PMU event]
el-capacity OR cpu/el-capacity/ [Kernel PMU event]
el-commit OR cpu/el-commit/ [Kernel PMU event]
el-conflict OR cpu/el-conflict/ [Kernel PMU event]
el-start OR cpu/el-start/ [Kernel PMU event]
i915/actual-frequency/ [Kernel PMU event]
i915/bcs0-busy/ [Kernel PMU event]
i915/bcs0-sema/ [Kernel PMU event]
i915/bcs0-wait/ [Kernel PMU event]
i915/interrupts/ [Kernel PMU event]
i915/rc6-residency/ [Kernel PMU event]
i915/rcs0-busy/ [Kernel PMU event]
i915/rcs0-sema/ [Kernel PMU event]
i915/rcs0-wait/ [Kernel PMU event]
i915/requested-frequency/ [Kernel PMU event]
i915/vcs0-busy/ [Kernel PMU event]
i915/vcs0-sema/ [Kernel PMU event]
i915/vcs0-wait/ [Kernel PMU event]
i915/vecs0-busy/ [Kernel PMU event]
i915/vecs0-sema/ [Kernel PMU event]
i915/vecs0-wait/ [Kernel PMU event]
instructions OR cpu/instructions/ [Kernel PMU event]
mem-loads OR cpu/mem-loads/ [Kernel PMU event]
mem-stores OR cpu/mem-stores/ [Kernel PMU event]
msr/aperf/ [Kernel PMU event]
msr/cpu_thermal_margin/ [Kernel PMU event]
msr/mperf/ [Kernel PMU event]
msr/smi/ [Kernel PMU event]
msr/tsc/ [Kernel PMU event]
power/energy-cores/ [Kernel PMU event]
power/energy-gpu/ [Kernel PMU event]
power/energy-pkg/ [Kernel PMU event]
power/energy-ram/ [Kernel PMU event]
ref-cycles OR cpu/ref-cycles/ [Kernel PMU event]
topdown-fetch-bubbles OR cpu/topdown-fetch-bubbles/ [Kernel PMU event]
topdown-recovery-bubbles OR cpu/topdown-recovery-bubbles/ [Kernel PMU event]
topdown-slots-issued OR cpu/topdown-slots-issued/ [Kernel PMU event]
topdown-slots-retired OR cpu/topdown-slots-retired/ [Kernel PMU event]
topdown-total-slots OR cpu/topdown-total-slots/ [Kernel PMU event]
tx-abort OR cpu/tx-abort/ [Kernel PMU event]
tx-capacity OR cpu/tx-capacity/ [Kernel PMU event]
tx-commit OR cpu/tx-commit/ [Kernel PMU event]
tx-conflict OR cpu/tx-conflict/ [Kernel PMU event]
tx-start OR cpu/tx-start/ [Kernel PMU event]
uncore_cbox_0/clockticks/ [Kernel PMU event]
uncore_cbox_1/clockticks/ [Kernel PMU event]
uncore_cbox_2/clockticks/ [Kernel PMU event]
uncore_cbox_3/clockticks/ [Kernel PMU event]
uncore_imc/data_reads/ [Kernel PMU event]
uncore_imc/data_writes/ [Kernel PMU event]
cache:
l1d.replacement
[L1D data line replacements]
l1d_pend_miss.fb_full
[Cycles a demand request was blocked due to Fill Buffers inavailability]
l1d_pend_miss.pending
[L1D miss oustandings duration in cycles]
l1d_pend_miss.pending_cycles
[Cycles with L1D load Misses outstanding]
l1d_pend_miss.pending_cycles_any
[Cycles with L1D load Misses outstanding from any thread on physical
core]
l1d_pend_miss.request_fb_full
[Number of times a request needed a FB entry but there was no entry
available for it. That is the FB unavailability was dominant reason
for blocking the request. A request includes cacheable/uncacheable
demands that is load, store or SW prefetch. HWP are e]
... snip ...
Metric Groups:
DSB:
DSB_Coverage
[Fraction of Uops delivered by the DSB (aka Decoded Icache; or Uop Cache)]
Frontend:
IFetch_Line_Utilization
[Rough Estimation of fraction of fetched lines bytes that were likely consumed by program instructions]
Frontend_Bandwidth:
DSB_Coverage
[Fraction of Uops delivered by the DSB (aka Decoded Icache; or Uop Cache)]
Memory_BW:
MLP
[Memory-Level-Parallelism (average number of L1 miss demand load when there is at least 1 such miss)]
Memory_Bound:
Load_Miss_Real_Latency
[Actual Average Latency for L1 data-cache miss demand loads]
MLP
[Memory-Level-Parallelism (average number of L1 miss demand load when there is at least 1 such miss)]
Memory_Lat:
Load_Miss_Real_Latency
[Actual Average Latency for L1 data-cache miss demand loads]
Pipeline:
CPI
[Cycles Per Instruction (threaded)]
ILP
[Instruction-Level-Parallelism (average number of uops executed when there is at least 1 uop executed)]
UPI
[Uops Per Instruction]
Ports_Utilization:
ILP
[Instruction-Level-Parallelism (average number of uops executed when there is at least 1 uop executed)]
Power:
C2_Pkg_Residency
[C2 residency percent per package]
C3_Core_Residency
[C3 residency percent per core]
C3_Pkg_Residency
[C3 residency percent per package]
C6_Core_Residency
[C6 residency percent per core]
C6_Pkg_Residency
[C6 residency percent per package]
C7_Core_Residency
[C7 residency percent per core]
C7_Pkg_Residency
[C7 residency percent per package]
Turbo_Utilization
[Average Frequency Utilization relative nominal frequency]
SMT:
CORE_CLKS
[Core actual clocks when any thread is active on the physical core]
CoreIPC
[Instructions Per Cycle (per physical core)]
SMT_2T_Utilization
[Fraction of cycles where both hardware threads were active]
Summary:
CLKS
[Per-thread actual clocks when the logical processor is active. This is called 'Clockticks' in VTune]
CPI
[Cycles Per Instruction (threaded)]
CPU_Utilization
[Average CPU Utilization]
Instructions
[Total number of retired Instructions]
Kernel_Utilization
[Fraction of cycles spent in Kernel mode]
SMT_2T_Utilization
[Fraction of cycles where both hardware threads were active]
TLB:
Page_Walks_Utilization
[Utilization of the core's Page Walker(s) serving STLB misses triggered by instruction/Load/Store accesses]
TopDownL1:
IPC
[Instructions Per Cycle (per logical thread)]
SLOTS
[Total issue-pipeline slots]
Unknown_Branches:
BAClear_Cost
[Average Branch Address Clear Cost (fraction of cycles)]Show events in one category
There are too many events, it would be helpful to just show events in one category.
Based on a non-accurate grep(perf list | grep ":$"), currently it has following groups:
cache
floating point
frontend
memory
other
pipeline
uncore
virtual memory
For example, list the events related to cache.
$perf list 'memory'
List of pre-defined events (to be used in -e):
L1-dcache-load-misses [Hardware cache event]
L1-dcache-loads [Hardware cache event]
L1-dcache-stores [Hardware cache event]
L1-icache-load-misses [Hardware cache event]
LLC-load-misses [Hardware cache event]
LLC-loads [Hardware cache event]
LLC-store-misses [Hardware cache event]
LLC-stores [Hardware cache event]
branch-load-misses [Hardware cache event]
branch-loads [Hardware cache event]
dTLB-load-misses [Hardware cache event]
dTLB-loads [Hardware cache event]
dTLB-store-misses [Hardware cache event]
dTLB-stores [Hardware cache event]
iTLB-load-misses [Hardware cache event]
iTLB-loads [Hardware cache event]
node-load-misses [Hardware cache event]
node-loads [Hardware cache event]
node-store-misses [Hardware cache event]
node-stores [Hardware cache event]Show Tracepoint event in category
Tracepoint event is a special category event, which is implemented by kernel ftrace.[?]
To list a summary of tracepoint events:
# perf list | awk -F: '/Tracepoint event/ { lib[$1]++ } END {
for (l in lib) { printf " %-16.16s: %d\n", l, lib[l] } }' | sort -t: -k2 -nr | column
syscalls : 626 x86_fpu : 12 smbus : 4 ftrace : 2
ext4 : 105 rtc : 12 rpm : 4 exceptions : 2
kvm : 72 kmem : 12 i2c : 4 cma : 2
xhci-hcd : 48 irq_matrix : 12 huge_memory : 4 vsyscall : 1
sunrpc : 36 filelock : 11 filemap : 4 udp : 1
irq_vectors : 32 cgroup : 9 bridge : 4 tlb : 1
writeback : 29 xdp : 8 alarmtimer : 4 sync_trace : 1
sched : 24 oom : 8 sock : 3 swiotlb : 1
power : 23 tcp : 7 skb : 3 rcu : 1
nfsd : 23 regulator : 7 msr : 3 qdisc : 1
block : 18 iommu : 7 initcall : 3 printk : 1
net : 17 dma_fence : 7 hwmon : 3 page_isolation : 1
vmscan : 16 libata : 6 drm : 3 nmi : 1
jbd2 : 16 thermal : 5 cpuhp : 3 napi : 1
clk : 16 scsi : 5 thermal_power_ : 2 migrate : 1
regmap : 15 ras : 5 task : 2 mdio : 1
random : 15 percpu : 5 signal : 2 mce : 1
kvmmmu : 14 module : 5 rseq : 2 fib : 1
fs_dax : 14 irq : 5 raw_syscalls : 2
compaction : 14 workqueue : 4 pagemap : 2
timer : 13 wbt : 4 gpio : 2From the above output, we can see syscalls has the most number of trace points.
Then if you want to see the tracepoint in one category, use the following command.
# perf list 'sched:*'
sched:sched_kthread_stop [Tracepoint event]
sched:sched_kthread_stop_ret [Tracepoint event]
sched:sched_migrate_task [Tracepoint event]
sched:sched_move_numa [Tracepoint event]
sched:sched_pi_setprio [Tracepoint event]
sched:sched_process_exec [Tracepoint event]
sched:sched_process_exit [Tracepoint event]
sched:sched_process_fork [Tracepoint event]
sched:sched_process_free [Tracepoint event]
sched:sched_process_hang [Tracepoint event]
sched:sched_process_wait [Tracepoint event]
sched:sched_stat_blocked [Tracepoint event]
sched:sched_stat_iowait [Tracepoint event]
sched:sched_stat_runtime [Tracepoint event]
sched:sched_stat_sleep [Tracepoint event]
sched:sched_stat_wait [Tracepoint event]
sched:sched_stick_numa [Tracepoint event]
sched:sched_swap_numa [Tracepoint event]
sched:sched_switch [Tracepoint event]
sched:sched_wait_task [Tracepoint event]
sched:sched_wake_idle_without_ipi [Tracepoint event]
sched:sched_wakeup [Tracepoint event]
sched:sched_wakeup_new [Tracepoint event]
sched:sched_waking [Tracepoint event]Event selection
Since perf is event oriented, one of the process to use it is to specify the event we want to monitor.
Generally, "-e" option is used to specify the event, while we may have several important cases.
Specify particular event
perf stat -e cycles dd if=/dev/zero of=/dev/null count=100000cycles is one event in perf stat, use "-e cycles" to specify to monitor this event.
And perf supports to specify several events
perf stat -e cycles,instructions dd if=/dev/zero of=/dev/null count=100000Modifiers
Events can optionally have a modifier by appending a colon and one or more modifiers.
Modifiers
Description
Example
u
monitor at priv level 3, 2, 1 (user)
event:u
k
monitor at priv level 0 (kernel)
event:k
h
monitor hypervisor events on a virtualization environment
event:h
H
monitor host machine on a virtualization environment
event:H
G
monitor guest machine on a virtualization environment
event:G
So the above command could be changed to
perf stat -e cycles:u dd if=/dev/zero of=/dev/null count=100000Then this will only count user level events.
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