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BACKPORT: perf tools: Document the perf sysctls 

perf_event_paranoid was only documented in source code and a perf error
message.  Copy the documentation from the error message to
Documentation/sysctl/kernel.txt.

Conflicts:
	Documentation/sysctl/kernel.txt
	tools/perf/util/evsel.c

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/20160119213515.GG2637@decadent.org.uk
[ Remove reference to external Documentation file, provide info inline, as before ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Bug: 29054680
Bug: 29119870
Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org>
Change-Id: I13e73cfb2ad761c94762d0c8196df7725abdf5c5
(cherry picked from commit 746938f9d97d74f6c2833a0ede49506bdfcd89e4)
This commit is contained in:
Ben Hutchings 2016-01-19 21:35:15 +00:00 committed by Gerrit - the friendly Code Review server
parent 96ff964ccf
commit c55763e4f7
2 changed files with 35 additions and 21 deletions
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41
Documentation/sysctl/kernel.txt
View File

@ -51,8 +51,9 @@ show up in /proc/sys/kernel:
- overflowuid
- panic
- panic_on_oops
- panic_on_unrecovered_nmi
- panic_on_stackoverflow
- panic_on_unrecovered_nmi
- perf_event_paranoid
- pid_max
- powersave-nap [ PPC only ]
- printk
@ -427,19 +428,6 @@ the recommended setting is 60.
==============================================================
panic_on_unrecovered_nmi:
The default Linux behaviour on an NMI of either memory or unknown is
to continue operation. For many environments such as scientific
computing it is preferable that the box is taken out and the error
dealt with than an uncorrected parity/ECC error get propagated.
A small number of systems do generate NMI's for bizarre random reasons
such as power management so the default is off. That sysctl works like
the existing panic controls already in that directory.
==============================================================
panic_on_oops:
Controls the kernel's behaviour when an oops or BUG is encountered.
@ -459,7 +447,6 @@ This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled.
0: try to continue operation.
1: panic immediately.
==============================================================
@ -489,6 +476,30 @@ allowed to execute.
==============================================================
panic_on_unrecovered_nmi:
The default Linux behaviour on an NMI of either memory or unknown is
to continue operation. For many environments such as scientific
computing it is preferable that the box is taken out and the error
dealt with than an uncorrected parity/ECC error get propagated.
A small number of systems do generate NMI's for bizarre random reasons
such as power management so the default is off. That sysctl works like
the existing panic controls already in that directory.
==============================================================
perf_event_paranoid:
Controls use of the performance events system by unprivileged
users (without CAP_SYS_ADMIN). The default value is 1.
-1: Allow use of (almost) all events by all users
>=0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
>=1: Disallow CPU event access by users without CAP_SYS_ADMIN
>=2: Disallow kernel profiling by users without CAP_SYS_ADMIN
==============================================================
pid_max:

15
tools/perf/util/evsel.c
View File

@ -1515,12 +1515,15 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel,
case EPERM:
case EACCES:
return scnprintf(msg, size,
"You may not have permission to collect %sstats.\n"
"Consider tweaking /proc/sys/kernel/perf_event_paranoid:\n"
" -1 - Not paranoid at all\n"
" 0 - Disallow raw tracepoint access for unpriv\n"
" 1 - Disallow cpu events for unpriv\n"
" 2 - Disallow kernel profiling for unpriv",
"You may not have permission to collect %sstats.\n\n"
"Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n"
"which controls use of the performance events system by\n"
"unprivileged users (without CAP_SYS_ADMIN).\n\n"
"The default value is 1:\n\n"
" -1: Allow use of (almost) all events by all users\n"
">= 0: Disallow raw tracepoint access by users without CAP_IOC_LOCK\n"
">= 1: Disallow CPU event access by users without CAP_SYS_ADMIN\n"
">= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN",
target->system_wide ? "system-wide " : "");
case ENOENT:
return scnprintf(msg, size, "The %s event is not supported.",