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perf_event_open.2: Fix prctl behavior description 

Some discussion on the linux-perf-users list has turned up that
the perf_event_open.2 description of how
PR_TASK_PERF_EVENTS_ENABLE / PR_TASK_PERF_EVENTS_DISABLE prctl()
works is misleading.

The descriptions were based on the tools/perf/design.txt document
which describes behavior that was removed in 082ff5a2767a06 (prior
to 2.6.31, the first release with perf_event_open support).

I have written some tests in my perf_event_tests testsuite that
verifies the behavior of prctl() in this case.

Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Vince Weaver 2018-06-11 13:26:52 -04:00 committed by Michael Kerrisk
parent 68bd4ad98c
commit d134c42971
1 changed files with 7 additions and 7 deletions
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14
man2/perf_event_open.2
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@ -2927,18 +2927,18 @@ a previous
.BR bpf (2)
system call.
.SS Using prctl(2)
A process can enable or disable all the event groups that are
attached to it using the
A process can enable or disable all currently open event groups
using the
.BR prctl (2)
.B PR_TASK_PERF_EVENTS_ENABLE
and
.B PR_TASK_PERF_EVENTS_DISABLE
operations.
This applies to all counters on the calling process, whether created by
this process or by another, and does not affect any counters that this
process has created on other processes.
It enables or disables only
the group leaders, not any other members in the groups.
This applies only to events created locally by the calling process.
This does not apply to events created by other processes attached
to the calling process or inherited events from a parent process.
Only group leaders are enabled and disabled,
not any other members of the groups.
.SS perf_event related configuration files
.PP
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