1 perf.data directory format
2
3 DISCLAIMER This is not ABI yet and is subject to possible change
4 in following versions of perf. We will remove this
5 disclaimer once the directory format soaks in.
6
7
8 This document describes the on-disk perf.data directory format.
9
10 The layout is described by HEADER_DIR_FORMAT feature.
11 Currently it holds only version number (0):
12
13 HEADER_DIR_FORMAT = 24
14
15 struct {
16 uint64_t version;
17 }
18
19 The current only version value 0 means that:
20 - there is a single perf.data file named 'data' within the directory.
21 e.g.
22
23 $ tree -ps perf.data
24 perf.data
25 └── [-rw------- 25912] data
26
27 Future versions are expected to describe different data files
28 layout according to special needs.
29
30 Currently the only 'perf record' option to output to a directory is
31 the --kcore option which puts a copy of /proc/kcore into the directory.
32 e.g.
33
34 $ sudo perf record --kcore uname
35 Linux
36 [ perf record: Woken up 1 times to write data ]
37 [ perf record: Captured and wrote 0.015 MB perf.data (9 samples) ]
38 $ sudo tree -ps perf.data
39 perf.data
40 ├── [-rw------- 23744] data
41 └── [drwx------ 4096] kcore_dir
42 ├── [-r-------- 6731125] kallsyms
43 ├── [-r-------- 40230912] kcore
44 └── [-r-------- 5419] modules
45
46 1 directory, 4 files
47 $ sudo perf script -v
48 build id event received for vmlinux: 1eaa285996affce2d74d8e66dcea09a80c9941de
49 build id event received for [vdso]: 8bbaf5dc62a9b644b4d4e4539737e104e4a84541
50 build id event received for /lib/x86_64-linux-gnu/libc-2.28.so: 5b157f49586a3ca84d55837f97ff466767dd3445
51 Samples for 'cycles' event do not have CPU attribute set. Skipping 'cpu' field.
52 Using CPUID GenuineIntel-6-8E-A
53 Using perf.data/kcore_dir/kcore for kernel data
54 Using perf.data/kcore_dir/kallsyms for symbols
55 perf 15316 2060795.480902: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
56 perf 15316 2060795.480906: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
57 perf 15316 2060795.480908: 7 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
58 perf 15316 2060795.480910: 119 cycles: ffffffffa2caa54a native_write_msr+0xa (vmlinux)
59 perf 15316 2060795.480912: 2109 cycles: ffffffffa2c9b7b0 native_apic_msr_write+0x0 (vmlinux)
60 perf 15316 2060795.480914: 37606 cycles: ffffffffa2f121fe perf_event_addr_filters_exec+0x2e (vmlinux)
61 uname 15316 2060795.480924: 588287 cycles: ffffffffa303a56d page_counter_try_charge+0x6d (vmlinux)
62 uname 15316 2060795.481067: 2261945 cycles: ffffffffa301438f kmem_cache_free+0x4f (vmlinux)
63 uname 15316 2060795.481643: 2172167 cycles: 7f1a48c393c0 _IO_un_link+0x0 (/lib/x86_64-linux-gnu/libc-2.28.so)
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