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Commit 2070e176 authored by Linux Build Service Account's avatar Linux Build Service Account Committed by Gerrit - the friendly Code Review server
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Merge "BACKPORT: perf tools: Document the perf sysctls"

parents d1cedc9e b01add1f

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.",