Commit 3379e0c3 authored by Ben Hutchings's avatar Ben Hutchings Committed by Arnaldo Carvalho de Melo
Browse files

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.

perf_cpu_time_max_percent was already documented but missing from the
list at the top, so add it there.

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>
parent 1f7c2541

Documentation/sysctl/kernel.txt

+13 −0
Original line number Diff line number Diff line
@@ -58,6 +58,8 @@ show up in /proc/sys/kernel: 
- panic_on_stackoverflow

- panic_on_unrecovered_nmi

- panic_on_warn

- perf_cpu_time_max_percent

- perf_event_paranoid

- pid_max

- powersave-nap               [ PPC only ]

- printk
@@ -639,6 +641,17 @@ allowed to execute. 


==============================================================



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
@@ -2362,12 +2362,15 @@ 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.",

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