perf.data directory format
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DISCLAIMER This is not ABI yet and is subject to possible change
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in following versions of perf. We will remove this
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disclaimer once the directory format soaks in.
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This document describes the on-disk perf.data directory format.
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The layout is described by HEADER_DIR_FORMAT feature.
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Currently it holds only version number (0):
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HEADER_DIR_FORMAT = 24
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struct {
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uint64_t version;
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}
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The current only version value 0 means that:
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- there is a single perf.data file named 'data' within the directory.
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e.g.
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$ tree -ps perf.data
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perf.data
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└── [-rw------- 25912] data
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Future versions are expected to describe different data files
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layout according to special needs.
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Currently the only 'perf record' option to output to a directory is
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the --kcore option which puts a copy of /proc/kcore into the directory.
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e.g.
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$ sudo perf record --kcore uname
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Linux
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[ perf record: Woken up 1 times to write data ]
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[ perf record: Captured and wrote 0.015 MB perf.data (9 samples) ]
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$ sudo tree -ps perf.data
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perf.data
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├── [-rw------- 23744] data
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└── [drwx------ 4096] kcore_dir
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├── [-r-------- 6731125] kallsyms
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├── [-r-------- 40230912] kcore
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└── [-r-------- 5419] modules
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1 directory, 4 files
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$ sudo perf script -v
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build id event received for vmlinux: 1eaa285996affce2d74d8e66dcea09a80c9941de
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build id event received for [vdso]: 8bbaf5dc62a9b644b4d4e4539737e104e4a84541
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build id event received for /lib/x86_64-linux-gnu/libc-2.28.so: 5b157f49586a3ca84d55837f97ff466767dd3445
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Samples for 'cycles' event do not have CPU attribute set. Skipping 'cpu' field.
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Using CPUID GenuineIntel-6-8E-A
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Using perf.data/kcore_dir/kcore for kernel data
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Using perf.data/kcore_dir/kallsyms for symbols
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perf 15316 2060795.480902: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
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perf 15316 2060795.480906: 1 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
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perf 15316 2060795.480908: 7 cycles: ffffffffa2caa548 native_write_msr+0x8 (vmlinux)
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perf 15316 2060795.480910: 119 cycles: ffffffffa2caa54a native_write_msr+0xa (vmlinux)
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perf 15316 2060795.480912: 2109 cycles: ffffffffa2c9b7b0 native_apic_msr_write+0x0 (vmlinux)
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perf 15316 2060795.480914: 37606 cycles: ffffffffa2f121fe perf_event_addr_filters_exec+0x2e (vmlinux)
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uname 15316 2060795.480924: 588287 cycles: ffffffffa303a56d page_counter_try_charge+0x6d (vmlinux)
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uname 15316 2060795.481067: 2261945 cycles: ffffffffa301438f kmem_cache_free+0x4f (vmlinux)
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uname 15316 2060795.481643: 2172167 cycles: 7f1a48c393c0 _IO_un_link+0x0 (/lib/x86_64-linux-gnu/libc-2.28.so)
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