From: Igor Lubashev <iluba...@akamai.com>
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.): 1601964
#
# Overhead Command Shared Object Symbol
# ........ ....... ................ ..........................
#
28.14% sleep [kernel.vmlinux] [k] __rb_erase_color
27.21% sleep [kernel.vmlinux] [k] unmap_page_range
27.20% sleep ld-2.29.so [.] __tunable_get_val
15.24% sleep [kernel.vmlinux] [k] thp_get_unmapped_area
1.96% perf [kernel.vmlinux] [k] perf_event_exec
0.22% perf [kernel.vmlinux] [k] native_sched_clock
0.02% perf [kernel.vmlinux] [k] intel_bts_enable_local
0.00% perf [kernel.vmlinux] [k] native_write_msr
#
# (Tip: Boolean options have negative forms, e.g.: perf report --no-children)
#
$
Reported-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Signed-off-by: Igor Lubashev <iluba...@akamai.com>
Tested-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Tested-by: Mathieu Poirier <mathieu.poir...@linaro.org>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Alexey Budankov <alexey.budan...@linux.intel.com>
Cc: James Morris <jmor...@namei.org>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Suzuki Poulouse <suzuki.poul...@arm.com>
Cc: linux-arm-ker...@lists.infradead.org
Link:
http://lkml.kernel.org/r/1566869956-7154-4-git-send-email-iluba...@akamai.com
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
tools/perf/util/evsel.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 7c704b8f0e5c..d4540bfe4574 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -282,7 +282,7 @@ struct evsel *perf_evsel__new_idx(struct perf_event_attr
*attr, int idx)
static bool perf_event_can_profile_kernel(void)
{
- return perf_event_paranoid_check(-1);
+ return perf_event_paranoid_check(1);
}
struct evsel *perf_evsel__new_cycles(bool precise)
--
2.21.0
