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Commit b01add1f authored by Ben Hutchings's avatar Ben Hutchings Committed by Dennis Cagle
Browse files

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

Git-repo: https://android.googlesource.com/kernel/common.git


Git-commit: b79154b8f7702f6e8a56ce9f1355f841cec16c37
Signed-off-by: default avatarBen 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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Bug: 29054680
Bug: 29119870
Signed-off-by: default avatarDennis Cagle <d-cagle@codeaurora.org>
Change-Id: I13e73cfb2ad761c94762d0c8196df7725abdf5c5
(cherry picked from commit 746938f9d97d74f6c2833a0ede49506bdfcd89e4)
parent 995bb603

Documentation/sysctl/kernel.txt

+26 −15
Original line number Diff line number Diff line
@@ -56,8 +56,9 @@ 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
@@ -552,19 +553,6 @@ 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.
@@ -584,7 +572,6 @@ This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled. 


0: try to continue operation.



1: panic immediately.



==============================================================
@@ -614,6 +601,30 @@ 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:

tools/perf/util/evsel.c

+9 −6
Original line number Diff line number Diff line
@@ -2067,12 +2067,15 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel, struct target *target, 
	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.",