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aa97293ff1
Perf was too restrictive about sysctl kernel.perf_event_paranoid. The
kernel only disallows profiling when perf_event_paranoid > 1. Make perf
do the same.
Committer testing:
For a non-root user:
$ id
uid=1000(acme) gid=1000(acme) groups=1000(acme),10(wheel) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
$
Before:
We were restricting it to just userspace (:u suffix) even for a
workload started by the user:
$ perf record sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ]
$ perf evlist
cycles:u
$ perf evlist -v
cycles:u: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD, read_format: ID, disabled: 1, inherit: 1, exclude_kernel: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
$ perf report --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
# Total Lost Samples: 0
#
# Samples: 8 of event 'cycles:u'
# Event count (approx.): 1040396
#
# Overhead Command Shared Object Symbol
# ........ ....... ................ ......................
#
68.36% sleep libc-2.29.so [.] _dl_addr
27.33% sleep ld-2.29.so [.] dl_main
3.80% sleep ld-2.29.so [.] _dl_setup_hash
#
# (Tip: Order by the overhead of source file name and line number: perf report -s srcline)
#
$
$
After:
When the kernel allows profiling the kernel in that scenario:
$ perf record sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.023 MB perf.data (11 samples) ]
$ perf evlist
cycles
$ perf evlist -v
cycles: size: 112, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD, read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, precise_ip: 3, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
$
$ perf report --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
# Total Lost Samples: 0
#
# Samples: 11 of event 'cycles'
# Event count (approx.):
|
History
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| .. | ||
| accounting | ||
| arch | ||
| bpf | ||
| build | ||
| cgroup | ||
| crypto | ||
| debugging | ||
| firewire | ||
| firmware | ||
| gpio | ||
| hv | ||
| iio | ||
| include | ||
| io_uring | ||
| kvm/kvm_stat | ||
| laptop | ||
| leds | ||
| lib | ||
| memory-model | ||
| nfsd | ||
| objtool | ||
| pci | ||
| pcmcia | ||
| perf | ||
| power | ||
| scripts | ||
| spi | ||
| testing | ||
| thermal/tmon | ||
| time | ||
| usb | ||
| virtio | ||
| vm | ||
| wmi | ||
| Makefile | ||