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f4f346c346
Build-ID processing goodies
---------------------------
Build-IDs are content based hashes to link regions of memory to ELF files
in post processing. They have been available in distros for quite a while:
$ file /bin/bash
/bin/bash: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV),
dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2,
BuildID[sha1]=707a1c670cd72f8e55ffedfbe94ea98901b7ce3a,
for GNU/Linux 3.2.0, stripped
It is possible to ask the kernel to get it from mmap executable backing
storage at time they are being put in place and send it as metadata at
that moment to have in perf.data.
Prefer that across the board to speed up 'record' time - it post processes
the samples to find binaries touched by any samples and to save them with
build-ID. It can skip reading build-ID in userspace if it comes from the
kernel.
perf record
-----------
* Make --buildid-mmap default. The kernel can generate MMAP2 events
with a build-ID from ELF header. Use that by default instead of using
inode and device ID to identify binaries. It also can be disabled
with --no-buildid-mmap.
* Use BPF for -u/--uid option to sample processes belong to a user.
BPF can track user processes more accurately and the existing logic
often fails to get the list of processes due to race with reading the
/proc filesystem.
* Generate PERF_RECORD_BPF_METADATA when it profiles BPF programs and
they have variables starting with "bpf_metadata_". This will help to
identify BPF objects used in the profile. This has been supported in
bpftool for some time and allows the recording of metadata such as
commit hashes, versions, etc, that now gets recorded in perf.data as
well.
* Collect list of DSOs touched in the sample callchains as well as in
the sample itself. This would increase the processing time at the end
of record, but can improve the data quality.
perf stat
---------
* Add a new 'drm' pseudo-PMU support like in 'hwmon'. It can collect
DRM usage stats using fdinfo in /proc.
On my Intel laptop, it shows like below:
$ perf list drm
...
drm:
drm-active-stolen-system0
[Total memory active in one or more engines. Unit: drm_i915]
drm-active-system0
[Total memory active in one or more engines. Unit: drm_i915]
drm-engine-capacity-video
[Engine capacity. Unit: drm_i915]
drm-engine-copy
[Utilization in ns. Unit: drm_i915]
drm-engine-render
[Utilization in ns. Unit: drm_i915]
drm-engine-video
[Utilization in ns. Unit: drm_i915]
...
$ sudo perf stat -a -e drm-engine-render,drm-engine-video,drm-engine-capacity-video sleep 1
Performance counter stats for 'system wide':
48,137,316,988,873 ns drm-engine-render
34,452,696,746 ns drm-engine-video
20 capacity drm-engine-capacity-video
1.002086194 seconds time elapsed
perf list
---------
* Add description for software events. The description is in JSON format
and the event parser now can handle the software events like others
(for example, it's case-insensitive and subject to wildcard matching).
$ perf list software
List of pre-defined events (to be used in -e or -M):
software:
alignment-faults
[Number of kernel handled memory alignment faults. Unit: software]
bpf-output
[An event used by BPF programs to write to the perf ring buffer. Unit: software]
cgroup-switches
[Number of context switches to a task in a different cgroup. Unit: software]
context-switches
[Number of context switches [This event is an alias of cs]. Unit: software]
cpu-clock
[Per-CPU high-resolution timer based event. Unit: software]
cpu-migrations
[Number of times a process has migrated to a new CPU [This event is an alias of migrations]. Unit: software]
cs
[Number of context switches [This event is an alias of context-switches]. Unit: software]
dummy
[A placeholder event that doesn't count anything. Unit: software]
emulation-faults
[Number of kernel handled unimplemented instruction faults handled through emulation. Unit: software]
faults
[Number of page faults [This event is an alias of page-faults]. Unit: software]
major-faults
[Number of major page faults. Major faults require I/O to handle. Unit: software]
migrations
[Number of times a process has migrated to a new CPU [This event is an alias of cpu-migrations]. Unit: software]
minor-faults
[Number of minor page faults. Minor faults don't require I/O to handle. Unit: software]
page-faults
[Number of page faults [This event is an alias of faults]. Unit: software]
task-clock
[Per-task high-resolution timer based event. Unit: software]
perf ftrace
-----------
* Add -e/--events option to perf ftrace latency to measure latency
between the two events instead of a function.
$ sudo perf ftrace latency -ab -e i915_request_wait_begin,i915_request_wait_end --hide-empty -- sleep 1
# DURATION | COUNT | GRAPH |
256 - 512 us | 4 | ###### |
2 - 4 ms | 2 | ### |
4 - 8 ms | 12 | ################### |
8 - 16 ms | 10 | ################ |
# statistics (in usec)
total time: 194915
avg time: 6961
max time: 12855
min time: 373
count: 28
* Add new function graph tracer options (--graph-opts) to display more
info like arguments and return value. They will be passed to the
kernel ftrace directly.
$ sudo perf ftrace -G vfs_write --graph-opts retval,retaddr
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
...
5) | mutex_unlock() { /* <-rb_simple_write+0xda/0x150 */
5) 0.188 us | local_clock(); /* <-lock_release+0x2ad/0x440 ret=0x3bf2a3cf90e */
5) | rt_mutex_slowunlock() { /* <-rb_simple_write+0xda/0x150 */
5) | _raw_spin_lock_irqsave() { /* <-rt_mutex_slowunlock+0x4f/0x200 */
5) 0.123 us | preempt_count_add(); /* <-_raw_spin_lock_irqsave+0x23/0x90 ret=0x0 */
5) 0.128 us | local_clock(); /* <-__lock_acquire.isra.0+0x17a/0x740 ret=0x3bf2a3cfc8b */
5) 0.086 us | do_raw_spin_trylock(); /* <-_raw_spin_lock_irqsave+0x4a/0x90 ret=0x1 */
5) 0.845 us | } /* _raw_spin_lock_irqsave ret=0x292 */
...
misc
----
* Add perf archive --exclude-buildids <FILE> option to skip some binaries.
The format of the FILE should be same as an output of perf buildid-list.
* Get rid of dependency of libcrypto. It was just to get SHA-1 hash so
implement it directly like in the kernel. A side effect is that it
needs -fno-strict-aliasing compiler option (again, like in the kernel).
* Convert all shell script tests to use bash.
Reviewed-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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Merge tag 'perf-tools-for-v6.17-2025-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
Pull perf tools updates from Namhyung Kim:
"Build-ID processing goodies:
Build-IDs are content based hashes to link regions of memory to ELF
files in post processing. They have been available in distros for
quite a while:
$ file /bin/bash
/bin/bash: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV),
dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2,
BuildID[sha1]=707a1c670cd72f8e55ffedfbe94ea98901b7ce3a,
for GNU/Linux 3.2.0, stripped
It is possible to ask the kernel to get it from mmap executable
backing storage at time they are being put in place and send it as
metadata at that moment to have in perf.data.
Prefer that across the board to speed up 'record' time - it post
processes the samples to find binaries touched by any samples and
to save them with build-ID. It can skip reading build-ID in
userspace if it comes from the kernel.
perf record:
* Make --buildid-mmap default. The kernel can generate MMAP2 events
with a build-ID from ELF header. Use that by default instead of using
inode and device ID to identify binaries. It also can be disabled
with --no-buildid-mmap.
* Use BPF for -u/--uid option to sample processes belong to a user.
BPF can track user processes more accurately and the existing logic
often fails to get the list of processes due to race with reading the
/proc filesystem.
* Generate PERF_RECORD_BPF_METADATA when it profiles BPF programs and
they have variables starting with "bpf_metadata_". This will help to
identify BPF objects used in the profile. This has been supported in
bpftool for some time and allows the recording of metadata such as
commit hashes, versions, etc, that now gets recorded in perf.data as
well.
* Collect list of DSOs touched in the sample callchains as well as in
the sample itself. This would increase the processing time at the end
of record, but can improve the data quality.
perf stat:
* Add a new 'drm' pseudo-PMU support like in 'hwmon'. It can collect
DRM usage stats using fdinfo in /proc.
On my Intel laptop, it shows like below:
$ perf list drm
...
drm:
drm-active-stolen-system0
[Total memory active in one or more engines. Unit: drm_i915]
drm-active-system0
[Total memory active in one or more engines. Unit: drm_i915]
drm-engine-capacity-video
[Engine capacity. Unit: drm_i915]
drm-engine-copy
[Utilization in ns. Unit: drm_i915]
drm-engine-render
[Utilization in ns. Unit: drm_i915]
drm-engine-video
[Utilization in ns. Unit: drm_i915]
...
$ sudo perf stat -a -e drm-engine-render,drm-engine-video,drm-engine-capacity-video sleep 1
Performance counter stats for 'system wide':
48,137,316,988,873 ns drm-engine-render
34,452,696,746 ns drm-engine-video
20 capacity drm-engine-capacity-video
1.002086194 seconds time elapsed
perf list
* Add description for software events. The description is in JSON format
and the event parser now can handle the software events like others
(for example, it's case-insensitive and subject to wildcard matching).
$ perf list software
List of pre-defined events (to be used in -e or -M):
software:
alignment-faults
[Number of kernel handled memory alignment faults. Unit: software]
bpf-output
[An event used by BPF programs to write to the perf ring buffer. Unit: software]
cgroup-switches
[Number of context switches to a task in a different cgroup. Unit: software]
context-switches
[Number of context switches [This event is an alias of cs]. Unit: software]
cpu-clock
[Per-CPU high-resolution timer based event. Unit: software]
cpu-migrations
[Number of times a process has migrated to a new CPU [This event is an alias of migrations]. Unit: software]
cs
[Number of context switches [This event is an alias of context-switches]. Unit: software]
dummy
[A placeholder event that doesn't count anything. Unit: software]
emulation-faults
[Number of kernel handled unimplemented instruction faults handled through emulation. Unit: software]
faults
[Number of page faults [This event is an alias of page-faults]. Unit: software]
major-faults
[Number of major page faults. Major faults require I/O to handle. Unit: software]
migrations
[Number of times a process has migrated to a new CPU [This event is an alias of cpu-migrations]. Unit: software]
minor-faults
[Number of minor page faults. Minor faults don't require I/O to handle. Unit: software]
page-faults
[Number of page faults [This event is an alias of faults]. Unit: software]
task-clock
[Per-task high-resolution timer based event. Unit: software]
perf ftrace:
* Add -e/--events option to perf ftrace latency to measure latency
between the two events instead of a function.
$ sudo perf ftrace latency -ab -e i915_request_wait_begin,i915_request_wait_end --hide-empty -- sleep 1
# DURATION | COUNT | GRAPH |
256 - 512 us | 4 | ###### |
2 - 4 ms | 2 | ### |
4 - 8 ms | 12 | ################### |
8 - 16 ms | 10 | ################ |
# statistics (in usec)
total time: 194915
avg time: 6961
max time: 12855
min time: 373
count: 28
* Add new function graph tracer options (--graph-opts) to display more
info like arguments and return value. They will be passed to the
kernel ftrace directly.
$ sudo perf ftrace -G vfs_write --graph-opts retval,retaddr
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
...
5) | mutex_unlock() { /* <-rb_simple_write+0xda/0x150 */
5) 0.188 us | local_clock(); /* <-lock_release+0x2ad/0x440 ret=0x3bf2a3cf90e */
5) | rt_mutex_slowunlock() { /* <-rb_simple_write+0xda/0x150 */
5) | _raw_spin_lock_irqsave() { /* <-rt_mutex_slowunlock+0x4f/0x200 */
5) 0.123 us | preempt_count_add(); /* <-_raw_spin_lock_irqsave+0x23/0x90 ret=0x0 */
5) 0.128 us | local_clock(); /* <-__lock_acquire.isra.0+0x17a/0x740 ret=0x3bf2a3cfc8b */
5) 0.086 us | do_raw_spin_trylock(); /* <-_raw_spin_lock_irqsave+0x4a/0x90 ret=0x1 */
5) 0.845 us | } /* _raw_spin_lock_irqsave ret=0x292 */
...
Misc:
* Add perf archive --exclude-buildids <FILE> option to skip some binaries.
The format of the FILE should be same as an output of perf buildid-list.
* Get rid of dependency of libcrypto. It was just to get SHA-1 hash so
implement it directly like in the kernel. A side effect is that it
needs -fno-strict-aliasing compiler option (again, like in the kernel).
* Convert all shell script tests to use bash"
* tag 'perf-tools-for-v6.17-2025-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (179 commits)
perf record: Cache build-ID of hit DSOs only
perf test: Ensure lock contention using pipe mode
perf python: Stop using deprecated PyUnicode_AsString()
perf list: Skip ABI PMUs when printing pmu values
perf list: Remove tracepoint printing code
perf tp_pmu: Add event APIs
perf tp_pmu: Factor existing tracepoint logic to new file
perf parse-events: Remove non-json software events
perf jevents: Add common software event json
perf tools: Remove libtraceevent in .gitignore
perf test: Fix comment ordering
perf sort: Use perf_env to set arch sort keys and header
perf test: Move PERF_SAMPLE_WEIGHT_STRUCT parsing to common test
perf sample: Remove arch notion of sample parsing
perf env: Remove global perf_env
perf trace: Avoid global perf_env with evsel__env
perf auxtrace: Pass perf_env from session through to mmap read
perf machine: Explicitly pass in host perf_env
perf bench synthesize: Avoid use of global perf_env
perf top: Make perf_env locally scoped
...
|
||
|---|---|---|
| .. | ||
| arch | ||
| bench | ||
| check-header_ignore_hunks/lib | ||
| dlfilters | ||
| Documentation | ||
| include/perf | ||
| jvmti | ||
| pmu-events | ||
| python | ||
| scripts | ||
| tests | ||
| trace | ||
| ui | ||
| util | ||
| .gitignore | ||
| Build | ||
| builtin-annotate.c | ||
| builtin-bench.c | ||
| builtin-buildid-cache.c | ||
| builtin-buildid-list.c | ||
| builtin-c2c.c | ||
| builtin-check.c | ||
| builtin-config.c | ||
| builtin-daemon.c | ||
| builtin-data.c | ||
| builtin-diff.c | ||
| builtin-evlist.c | ||
| builtin-ftrace.c | ||
| builtin-help.c | ||
| builtin-inject.c | ||
| builtin-kallsyms.c | ||
| builtin-kmem.c | ||
| builtin-kvm.c | ||
| builtin-kwork.c | ||
| builtin-list.c | ||
| builtin-lock.c | ||
| builtin-mem.c | ||
| builtin-probe.c | ||
| builtin-record.c | ||
| builtin-report.c | ||
| builtin-sched.c | ||
| builtin-script.c | ||
| builtin-stat.c | ||
| builtin-timechart.c | ||
| builtin-top.c | ||
| builtin-trace.c | ||
| builtin-version.c | ||
| builtin.h | ||
| check-headers.sh | ||
| command-list.txt | ||
| CREDITS | ||
| design.txt | ||
| Makefile | ||
| Makefile.config | ||
| Makefile.perf | ||
| MANIFEST | ||
| perf-archive.sh | ||
| perf-completion.sh | ||
| perf-iostat.sh | ||
| perf-read-vdso.c | ||
| perf-sys.h | ||
| perf.c | ||
| perf.h | ||