debugfs: Fix terminology inconsistency of dir name to mount debugfs filesystem. (156f5a78) · Commits · e / devices / android_kernel_samsung_smdk4412

Documentation/DocBook/debugobjects.tmpl

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -106,7 +106,7 @@
	number of errors are printk'ed including a full stack trace.		number of errors are printk'ed including a full stack trace.
	</para>		</para>
	<para>		<para>
	The statistics are available via debugfs/debug_objects/stats.		The statistics are available via /sys/kernel/debug/debug_objects/stats.
	They provide information about the number of warnings and the		They provide information about the number of warnings and the
	number of successful fixups along with information about the		number of successful fixups along with information about the
	usage of the internal tracking objects and the state of the		usage of the internal tracking objects and the state of the

Documentation/cdrom/packet-writing.txt

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -117,7 +117,7 @@ Using the pktcdvd debugfs interface

	To read pktcdvd device infos in human readable form, do:		To read pktcdvd device infos in human readable form, do:

	# cat /debug/pktcdvd/pktcdvd[0-7]/info		# cat /sys/kernel/debug/pktcdvd/pktcdvd[0-7]/info

	For a description of the debugfs interface look into the file:		For a description of the debugfs interface look into the file:

Documentation/fault-injection/fault-injection.txt

+35 −35

Original line number	Original line	Diff line number	Diff line
	@@ -29,16 +29,16 @@ o debugfs entries
	fault-inject-debugfs kernel module provides some debugfs entries for runtime		fault-inject-debugfs kernel module provides some debugfs entries for runtime
	configuration of fault-injection capabilities.		configuration of fault-injection capabilities.

	- /debug/fail*/probability:		- /sys/kernel/debug/fail*/probability:

	likelihood of failure injection, in percent.		likelihood of failure injection, in percent.
	Format: <percent>		Format: <percent>

	Note that one-failure-per-hundred is a very high error rate		Note that one-failure-per-hundred is a very high error rate
	for some testcases. Consider setting probability=100 and configure		for some testcases. Consider setting probability=100 and configure
	/debug/fail*/interval for such testcases.		/sys/kernel/debug/fail*/interval for such testcases.

	- /debug/fail*/interval:		- /sys/kernel/debug/fail*/interval:

	specifies the interval between failures, for calls to		specifies the interval between failures, for calls to
	should_fail() that pass all the other tests.		should_fail() that pass all the other tests.
	@@ -46,18 +46,18 @@ configuration of fault-injection capabilities.
	Note that if you enable this, by setting interval>1, you will		Note that if you enable this, by setting interval>1, you will
	probably want to set probability=100.		probably want to set probability=100.

	- /debug/fail*/times:		- /sys/kernel/debug/fail*/times:

	specifies how many times failures may happen at most.		specifies how many times failures may happen at most.
	A value of -1 means "no limit".		A value of -1 means "no limit".

	- /debug/fail*/space:		- /sys/kernel/debug/fail*/space:

	specifies an initial resource "budget", decremented by "size"		specifies an initial resource "budget", decremented by "size"
	on each call to should_fail(,size). Failure injection is		on each call to should_fail(,size). Failure injection is
	suppressed until "space" reaches zero.		suppressed until "space" reaches zero.

	- /debug/fail*/verbose		- /sys/kernel/debug/fail*/verbose

	Format: { 0 \| 1 \| 2 }		Format: { 0 \| 1 \| 2 }
	specifies the verbosity of the messages when failure is		specifies the verbosity of the messages when failure is
	@@ -65,17 +65,17 @@ configuration of fault-injection capabilities.
	log line per failure; '2' will print a call trace too -- useful		log line per failure; '2' will print a call trace too -- useful
	to debug the problems revealed by fault injection.		to debug the problems revealed by fault injection.

	- /debug/fail*/task-filter:		- /sys/kernel/debug/fail*/task-filter:

	Format: { 'Y' \| 'N' }		Format: { 'Y' \| 'N' }
	A value of 'N' disables filtering by process (default).		A value of 'N' disables filtering by process (default).
	Any positive value limits failures to only processes indicated by		Any positive value limits failures to only processes indicated by
	/proc/<pid>/make-it-fail==1.		/proc/<pid>/make-it-fail==1.

	- /debug/fail*/require-start:		- /sys/kernel/debug/fail*/require-start:
	- /debug/fail*/require-end:		- /sys/kernel/debug/fail*/require-end:
	- /debug/fail*/reject-start:		- /sys/kernel/debug/fail*/reject-start:
	- /debug/fail*/reject-end:		- /sys/kernel/debug/fail*/reject-end:

	specifies the range of virtual addresses tested during		specifies the range of virtual addresses tested during
	stacktrace walking. Failure is injected only if some caller		stacktrace walking. Failure is injected only if some caller
	@@ -84,26 +84,26 @@ configuration of fault-injection capabilities.
	Default required range is [0,ULONG_MAX) (whole of virtual address space).		Default required range is [0,ULONG_MAX) (whole of virtual address space).
	Default rejected range is [0,0).		Default rejected range is [0,0).

	- /debug/fail*/stacktrace-depth:		- /sys/kernel/debug/fail*/stacktrace-depth:

	specifies the maximum stacktrace depth walked during search		specifies the maximum stacktrace depth walked during search
	for a caller within [require-start,require-end) OR		for a caller within [require-start,require-end) OR
	[reject-start,reject-end).		[reject-start,reject-end).

	- /debug/fail_page_alloc/ignore-gfp-highmem:		- /sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem:

	Format: { 'Y' \| 'N' }		Format: { 'Y' \| 'N' }
	default is 'N', setting it to 'Y' won't inject failures into		default is 'N', setting it to 'Y' won't inject failures into
	highmem/user allocations.		highmem/user allocations.

	- /debug/failslab/ignore-gfp-wait:		- /sys/kernel/debug/failslab/ignore-gfp-wait:
	- /debug/fail_page_alloc/ignore-gfp-wait:		- /sys/kernel/debug/fail_page_alloc/ignore-gfp-wait:

	Format: { 'Y' \| 'N' }		Format: { 'Y' \| 'N' }
	default is 'N', setting it to 'Y' will inject failures		default is 'N', setting it to 'Y' will inject failures
	only into non-sleep allocations (GFP_ATOMIC allocations).		only into non-sleep allocations (GFP_ATOMIC allocations).

	- /debug/fail_page_alloc/min-order:		- /sys/kernel/debug/fail_page_alloc/min-order:

	specifies the minimum page allocation order to be injected		specifies the minimum page allocation order to be injected
	failures.		failures.
	@@ -166,13 +166,13 @@ o Inject slab allocation failures into module init/exit code
	#!/bin/bash		#!/bin/bash

	FAILTYPE=failslab		FAILTYPE=failslab
	echo Y > /debug/$FAILTYPE/task-filter		echo Y > /sys/kernel/debug/$FAILTYPE/task-filter
	echo 10 > /debug/$FAILTYPE/probability		echo 10 > /sys/kernel/debug/$FAILTYPE/probability
	echo 100 > /debug/$FAILTYPE/interval		echo 100 > /sys/kernel/debug/$FAILTYPE/interval
	echo -1 > /debug/$FAILTYPE/times		echo -1 > /sys/kernel/debug/$FAILTYPE/times
	echo 0 > /debug/$FAILTYPE/space		echo 0 > /sys/kernel/debug/$FAILTYPE/space
	echo 2 > /debug/$FAILTYPE/verbose		echo 2 > /sys/kernel/debug/$FAILTYPE/verbose
	echo 1 > /debug/$FAILTYPE/ignore-gfp-wait		echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait

	faulty_system()		faulty_system()
	{		{
	@@ -217,20 +217,20 @@ then
	exit 1		exit 1
	fi		fi

	cat /sys/module/$module/sections/.text > /debug/$FAILTYPE/require-start		cat /sys/module/$module/sections/.text > /sys/kernel/debug/$FAILTYPE/require-start
	cat /sys/module/$module/sections/.data > /debug/$FAILTYPE/require-end		cat /sys/module/$module/sections/.data > /sys/kernel/debug/$FAILTYPE/require-end

	echo N > /debug/$FAILTYPE/task-filter		echo N > /sys/kernel/debug/$FAILTYPE/task-filter
	echo 10 > /debug/$FAILTYPE/probability		echo 10 > /sys/kernel/debug/$FAILTYPE/probability
	echo 100 > /debug/$FAILTYPE/interval		echo 100 > /sys/kernel/debug/$FAILTYPE/interval
	echo -1 > /debug/$FAILTYPE/times		echo -1 > /sys/kernel/debug/$FAILTYPE/times
	echo 0 > /debug/$FAILTYPE/space		echo 0 > /sys/kernel/debug/$FAILTYPE/space
	echo 2 > /debug/$FAILTYPE/verbose		echo 2 > /sys/kernel/debug/$FAILTYPE/verbose
	echo 1 > /debug/$FAILTYPE/ignore-gfp-wait		echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-wait
	echo 1 > /debug/$FAILTYPE/ignore-gfp-highmem		echo 1 > /sys/kernel/debug/$FAILTYPE/ignore-gfp-highmem
	echo 10 > /debug/$FAILTYPE/stacktrace-depth		echo 10 > /sys/kernel/debug/$FAILTYPE/stacktrace-depth

	trap "echo 0 > /debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT		trap "echo 0 > /sys/kernel/debug/$FAILTYPE/probability" SIGINT SIGTERM EXIT

	echo "Injecting errors into the module $module... (interrupt to stop)"		echo "Injecting errors into the module $module... (interrupt to stop)"
	sleep 1000000		sleep 1000000

Documentation/kprobes.txt

+3 −3

Original line number	Original line	Diff line number	Diff line
	@@ -507,9 +507,9 @@ http://www.linuxsymposium.org/2006/linuxsymposium_procv2.pdf (pages 101-115)
	Appendix A: The kprobes debugfs interface		Appendix A: The kprobes debugfs interface

	With recent kernels (> 2.6.20) the list of registered kprobes is visible		With recent kernels (> 2.6.20) the list of registered kprobes is visible
	under the /debug/kprobes/ directory (assuming debugfs is mounted at /debug).		under the /sys/kernel/debug/kprobes/ directory (assuming debugfs is mounted at //sys/kernel/debug).

	/debug/kprobes/list: Lists all registered probes on the system		/sys/kernel/debug/kprobes/list: Lists all registered probes on the system

	c015d71a k vfs_read+0x0		c015d71a k vfs_read+0x0
	c011a316 j do_fork+0x0		c011a316 j do_fork+0x0
	@@ -525,7 +525,7 @@ virtual addresses that correspond to modules that've been unloaded),
	such probes are marked with [GONE]. If the probe is temporarily disabled,		such probes are marked with [GONE]. If the probe is temporarily disabled,
	such probes are marked with [DISABLED].		such probes are marked with [DISABLED].

	/debug/kprobes/enabled: Turn kprobes ON/OFF forcibly.		/sys/kernel/debug/kprobes/enabled: Turn kprobes ON/OFF forcibly.

	Provides a knob to globally and forcibly turn registered kprobes ON or OFF.		Provides a knob to globally and forcibly turn registered kprobes ON or OFF.
	By default, all kprobes are enabled. By echoing "0" to this file, all		By default, all kprobes are enabled. By echoing "0" to this file, all

Documentation/trace/ftrace.txt

+142 −91

Original line number	Original line	Diff line number	Diff line
	@@ -7,7 +7,6 @@ Copyright 2008 Red Hat Inc.
	(dual licensed under the GPL v2)		(dual licensed under the GPL v2)
	Reviewers: Elias Oltmanns, Randy Dunlap, Andrew Morton,		Reviewers: Elias Oltmanns, Randy Dunlap, Andrew Morton,
	John Kacur, and David Teigland.		John Kacur, and David Teigland.

	Written for: 2.6.28-rc2		Written for: 2.6.28-rc2

	Introduction		Introduction
	@@ -33,13 +32,26 @@ The File System
	Ftrace uses the debugfs file system to hold the control files as		Ftrace uses the debugfs file system to hold the control files as
	well as the files to display output.		well as the files to display output.

	To mount the debugfs system:		When debugfs is configured into the kernel (which selecting any ftrace
			option will do) the directory /sys/kernel/debug will be created. To mount
			this directory, you can add to your /etc/fstab file:

			debugfs /sys/kernel/debug debugfs defaults 0 0

			Or you can mount it at run time with:

	# mkdir /debug		mount -t debugfs nodev /sys/kernel/debug
	# mount -t debugfs nodev /debug

	( Note: it is more common to mount at /sys/kernel/debug, but for		For quicker access to that directory you may want to make a soft link to
	simplicity this document will use /debug)		it:

			ln -s /sys/kernel/debug /debug

			Any selected ftrace option will also create a directory called tracing
			within the debugfs. The rest of the document will assume that you are in
			the ftrace directory (cd /sys/kernel/debug/tracing) and will only concentrate
			on the files within that directory and not distract from the content with
			the extended "/sys/kernel/debug/tracing" path name.

	That's it! (assuming that you have ftrace configured into your kernel)		That's it! (assuming that you have ftrace configured into your kernel)

	@@ -389,18 +401,18 @@ trace_options
	The trace_options file is used to control what gets printed in		The trace_options file is used to control what gets printed in
	the trace output. To see what is available, simply cat the file:		the trace output. To see what is available, simply cat the file:

	cat /debug/tracing/trace_options		cat trace_options
	print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \		print-parent nosym-offset nosym-addr noverbose noraw nohex nobin \
	noblock nostacktrace nosched-tree nouserstacktrace nosym-userobj		noblock nostacktrace nosched-tree nouserstacktrace nosym-userobj

	To disable one of the options, echo in the option prepended with		To disable one of the options, echo in the option prepended with
	"no".		"no".

	echo noprint-parent > /debug/tracing/trace_options		echo noprint-parent > trace_options

	To enable an option, leave off the "no".		To enable an option, leave off the "no".

	echo sym-offset > /debug/tracing/trace_options		echo sym-offset > trace_options

	Here are the available options:		Here are the available options:

	@@ -476,11 +488,11 @@ sched_switch
	This tracer simply records schedule switches. Here is an example		This tracer simply records schedule switches. Here is an example
	of how to use it.		of how to use it.

	# echo sched_switch > /debug/tracing/current_tracer		# echo sched_switch > current_tracer
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# sleep 1		# sleep 1
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/trace		# cat trace

	# tracer: sched_switch		# tracer: sched_switch
	#		#
	@@ -583,13 +595,13 @@ new trace is saved.
	To reset the maximum, echo 0 into tracing_max_latency. Here is		To reset the maximum, echo 0 into tracing_max_latency. Here is
	an example:		an example:

	# echo irqsoff > /debug/tracing/current_tracer		# echo irqsoff > current_tracer
	# echo 0 > /debug/tracing/tracing_max_latency		# echo 0 > tracing_max_latency
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# ls -ltr		# ls -ltr
	[...]		[...]
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/latency_trace		# cat latency_trace
	# tracer: irqsoff		# tracer: irqsoff
	#		#
	irqsoff latency trace v1.1.5 on 2.6.26		irqsoff latency trace v1.1.5 on 2.6.26
	@@ -690,13 +702,13 @@ Like the irqsoff tracer, it records the maximum latency for
	which preemption was disabled. The control of preemptoff tracer		which preemption was disabled. The control of preemptoff tracer
	is much like the irqsoff tracer.		is much like the irqsoff tracer.

	# echo preemptoff > /debug/tracing/current_tracer		# echo preemptoff > current_tracer
	# echo 0 > /debug/tracing/tracing_max_latency		# echo 0 > tracing_max_latency
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# ls -ltr		# ls -ltr
	[...]		[...]
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/latency_trace		# cat latency_trace
	# tracer: preemptoff		# tracer: preemptoff
	#		#
	preemptoff latency trace v1.1.5 on 2.6.26-rc8		preemptoff latency trace v1.1.5 on 2.6.26-rc8
	@@ -837,13 +849,13 @@ tracer.
	Again, using this trace is much like the irqsoff and preemptoff		Again, using this trace is much like the irqsoff and preemptoff
	tracers.		tracers.

	# echo preemptirqsoff > /debug/tracing/current_tracer		# echo preemptirqsoff > current_tracer
	# echo 0 > /debug/tracing/tracing_max_latency		# echo 0 > tracing_max_latency
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# ls -ltr		# ls -ltr
	[...]		[...]
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/latency_trace		# cat latency_trace
	# tracer: preemptirqsoff		# tracer: preemptirqsoff
	#		#
	preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8		preemptirqsoff latency trace v1.1.5 on 2.6.26-rc8
	@@ -999,12 +1011,12 @@ slightly differently than we did with the previous tracers.
	Instead of performing an 'ls', we will run 'sleep 1' under		Instead of performing an 'ls', we will run 'sleep 1' under
	'chrt' which changes the priority of the task.		'chrt' which changes the priority of the task.

	# echo wakeup > /debug/tracing/current_tracer		# echo wakeup > current_tracer
	# echo 0 > /debug/tracing/tracing_max_latency		# echo 0 > tracing_max_latency
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# chrt -f 5 sleep 1		# chrt -f 5 sleep 1
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/latency_trace		# cat latency_trace
	# tracer: wakeup		# tracer: wakeup
	#		#
	wakeup latency trace v1.1.5 on 2.6.26-rc8		wakeup latency trace v1.1.5 on 2.6.26-rc8
	@@ -1114,11 +1126,11 @@ can be done from the debug file system. Make sure the
	ftrace_enabled is set; otherwise this tracer is a nop.		ftrace_enabled is set; otherwise this tracer is a nop.

	# sysctl kernel.ftrace_enabled=1		# sysctl kernel.ftrace_enabled=1
	# echo function > /debug/tracing/current_tracer		# echo function > current_tracer
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# usleep 1		# usleep 1
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/trace		# cat trace
	# tracer: function		# tracer: function
	#		#
	# TASK-PID CPU# TIMESTAMP FUNCTION		# TASK-PID CPU# TIMESTAMP FUNCTION
	@@ -1155,7 +1167,7 @@ int trace_fd;
	[...]		[...]
	int main(int argc, char *argv[]) {		int main(int argc, char *argv[]) {
	[...]		[...]
	trace_fd = open("/debug/tracing/tracing_enabled", O_WRONLY);		trace_fd = open(tracing_file("tracing_enabled"), O_WRONLY);
	[...]		[...]
	if (condition_hit()) {		if (condition_hit()) {
	write(trace_fd, "0", 1);		write(trace_fd, "0", 1);
	@@ -1163,26 +1175,20 @@ int main(int argc, char *argv[]) {
	[...]		[...]
	}		}

	Note: Here we hard coded the path name. The debugfs mount is not
	guaranteed to be at /debug (and is more commonly at
	/sys/kernel/debug). For simple one time traces, the above is
	sufficent. For anything else, a search through /proc/mounts may
	be needed to find where the debugfs file-system is mounted.


	Single thread tracing		Single thread tracing
	---------------------		---------------------

	By writing into /debug/tracing/set_ftrace_pid you can trace a		By writing into set_ftrace_pid you can trace a
	single thread. For example:		single thread. For example:

	# cat /debug/tracing/set_ftrace_pid		# cat set_ftrace_pid
	no pid		no pid
	# echo 3111 > /debug/tracing/set_ftrace_pid		# echo 3111 > set_ftrace_pid
	# cat /debug/tracing/set_ftrace_pid		# cat set_ftrace_pid
	3111		3111
	# echo function > /debug/tracing/current_tracer		# echo function > current_tracer
	# cat /debug/tracing/trace \| head		# cat trace \| head
	# tracer: function		# tracer: function
	#		#
	# TASK-PID CPU# TIMESTAMP FUNCTION		# TASK-PID CPU# TIMESTAMP FUNCTION
	@@ -1193,8 +1199,8 @@ no pid
	yum-updatesd-3111 [003] 1637.254683: lock_hrtimer_base <-hrtimer_try_to_cancel		yum-updatesd-3111 [003] 1637.254683: lock_hrtimer_base <-hrtimer_try_to_cancel
	yum-updatesd-3111 [003] 1637.254685: fget_light <-do_sys_poll		yum-updatesd-3111 [003] 1637.254685: fget_light <-do_sys_poll
	yum-updatesd-3111 [003] 1637.254686: pipe_poll <-do_sys_poll		yum-updatesd-3111 [003] 1637.254686: pipe_poll <-do_sys_poll
	# echo -1 > /debug/tracing/set_ftrace_pid		# echo -1 > set_ftrace_pid
	# cat /debug/tracing/trace \|head		# cat trace \|head
	# tracer: function		# tracer: function
	#		#
	# TASK-PID CPU# TIMESTAMP FUNCTION		# TASK-PID CPU# TIMESTAMP FUNCTION
	@@ -1216,6 +1222,51 @@ something like this simple program:
	#include <fcntl.h>		#include <fcntl.h>
	#include <unistd.h>		#include <unistd.h>

			#define _STR(x) #x
			#define STR(x) _STR(x)
			#define MAX_PATH 256

			const char *find_debugfs(void)
			{
			static char debugfs[MAX_PATH+1];
			static int debugfs_found;
			char type[100];
			FILE *fp;

			if (debugfs_found)
			return debugfs;

			if ((fp = fopen("/proc/mounts","r")) == NULL) {
			perror("/proc/mounts");
			return NULL;
			}

			while (fscanf(fp, "%*s %"
			STR(MAX_PATH)
			"s %99s %s %d %*d\n",
			debugfs, type) == 2) {
			if (strcmp(type, "debugfs") == 0)
			break;
			}
			fclose(fp);

			if (strcmp(type, "debugfs") != 0) {
			fprintf(stderr, "debugfs not mounted");
			return NULL;
			}

			debugfs_found = 1;

			return debugfs;
			}

			const char tracing_file(const char file_name)
			{
			static char trace_file[MAX_PATH+1];
			snprintf(trace_file, MAX_PATH, "%s/%s", find_debugfs(), file_name);
			return trace_file;
			}

	int main (int argc, char **argv)		int main (int argc, char **argv)
	{		{
	if (argc < 1)		if (argc < 1)
	@@ -1226,12 +1277,12 @@ int main (int argc, char **argv)
	char line[64];		char line[64];
	int s;		int s;

	ffd = open("/debug/tracing/current_tracer", O_WRONLY);		ffd = open(tracing_file("current_tracer"), O_WRONLY);
	if (ffd < 0)		if (ffd < 0)
	exit(-1);		exit(-1);
	write(ffd, "nop", 3);		write(ffd, "nop", 3);

	fd = open("/debug/tracing/set_ftrace_pid", O_WRONLY);		fd = open(tracing_file("set_ftrace_pid"), O_WRONLY);
	s = sprintf(line, "%d\n", getpid());		s = sprintf(line, "%d\n", getpid());
	write(fd, line, s);		write(fd, line, s);

	@@ -1383,22 +1434,22 @@ want, depending on your needs.
	tracing_cpu_mask file) or you might sometimes see unordered		tracing_cpu_mask file) or you might sometimes see unordered
	function calls while cpu tracing switch.		function calls while cpu tracing switch.

	hide: echo nofuncgraph-cpu > /debug/tracing/trace_options		hide: echo nofuncgraph-cpu > trace_options
	show: echo funcgraph-cpu > /debug/tracing/trace_options		show: echo funcgraph-cpu > trace_options

	- The duration (function's time of execution) is displayed on		- The duration (function's time of execution) is displayed on
	the closing bracket line of a function or on the same line		the closing bracket line of a function or on the same line
	than the current function in case of a leaf one. It is default		than the current function in case of a leaf one. It is default
	enabled.		enabled.

	hide: echo nofuncgraph-duration > /debug/tracing/trace_options		hide: echo nofuncgraph-duration > trace_options
	show: echo funcgraph-duration > /debug/tracing/trace_options		show: echo funcgraph-duration > trace_options

	- The overhead field precedes the duration field in case of		- The overhead field precedes the duration field in case of
	reached duration thresholds.		reached duration thresholds.

	hide: echo nofuncgraph-overhead > /debug/tracing/trace_options		hide: echo nofuncgraph-overhead > trace_options
	show: echo funcgraph-overhead > /debug/tracing/trace_options		show: echo funcgraph-overhead > trace_options
	depends on: funcgraph-duration		depends on: funcgraph-duration

	ie:		ie:
	@@ -1427,8 +1478,8 @@ want, depending on your needs.
	- The task/pid field displays the thread cmdline and pid which		- The task/pid field displays the thread cmdline and pid which
	executed the function. It is default disabled.		executed the function. It is default disabled.

	hide: echo nofuncgraph-proc > /debug/tracing/trace_options		hide: echo nofuncgraph-proc > trace_options
	show: echo funcgraph-proc > /debug/tracing/trace_options		show: echo funcgraph-proc > trace_options

	ie:		ie:

	@@ -1451,8 +1502,8 @@ want, depending on your needs.
	system clock since it started. A snapshot of this time is		system clock since it started. A snapshot of this time is
	given on each entry/exit of functions		given on each entry/exit of functions

	hide: echo nofuncgraph-abstime > /debug/tracing/trace_options		hide: echo nofuncgraph-abstime > trace_options
	show: echo funcgraph-abstime > /debug/tracing/trace_options		show: echo funcgraph-abstime > trace_options

	ie:		ie:

	@@ -1549,7 +1600,7 @@ listed in:

	available_filter_functions		available_filter_functions

	# cat /debug/tracing/available_filter_functions		# cat available_filter_functions
	put_prev_task_idle		put_prev_task_idle
	kmem_cache_create		kmem_cache_create
	pick_next_task_rt		pick_next_task_rt
	@@ -1561,12 +1612,12 @@ mutex_lock
	If I am only interested in sys_nanosleep and hrtimer_interrupt:		If I am only interested in sys_nanosleep and hrtimer_interrupt:

	# echo sys_nanosleep hrtimer_interrupt \		# echo sys_nanosleep hrtimer_interrupt \
	> /debug/tracing/set_ftrace_filter		> set_ftrace_filter
	# echo ftrace > /debug/tracing/current_tracer		# echo ftrace > current_tracer
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# usleep 1		# usleep 1
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/trace		# cat trace
	# tracer: ftrace		# tracer: ftrace
	#		#
	# TASK-PID CPU# TIMESTAMP FUNCTION		# TASK-PID CPU# TIMESTAMP FUNCTION
	@@ -1577,7 +1628,7 @@ If I am only interested in sys_nanosleep and hrtimer_interrupt:

	To see which functions are being traced, you can cat the file:		To see which functions are being traced, you can cat the file:

	# cat /debug/tracing/set_ftrace_filter		# cat set_ftrace_filter
	hrtimer_interrupt		hrtimer_interrupt
	sys_nanosleep		sys_nanosleep

	@@ -1597,7 +1648,7 @@ Note: It is better to use quotes to enclose the wild cards,
	otherwise the shell may expand the parameters into names		otherwise the shell may expand the parameters into names
	of files in the local directory.		of files in the local directory.

	# echo 'hrtimer_*' > /debug/tracing/set_ftrace_filter		# echo 'hrtimer_*' > set_ftrace_filter

	Produces:		Produces:

	@@ -1618,7 +1669,7 @@ Produces:

	Notice that we lost the sys_nanosleep.		Notice that we lost the sys_nanosleep.

	# cat /debug/tracing/set_ftrace_filter		# cat set_ftrace_filter
	hrtimer_run_queues		hrtimer_run_queues
	hrtimer_run_pending		hrtimer_run_pending
	hrtimer_init		hrtimer_init
	@@ -1644,17 +1695,17 @@ To append to the filters, use '>>'
	To clear out a filter so that all functions will be recorded		To clear out a filter so that all functions will be recorded
	again:		again:

	# echo > /debug/tracing/set_ftrace_filter		# echo > set_ftrace_filter
	# cat /debug/tracing/set_ftrace_filter		# cat set_ftrace_filter
	#		#

	Again, now we want to append.		Again, now we want to append.

	# echo sys_nanosleep > /debug/tracing/set_ftrace_filter		# echo sys_nanosleep > set_ftrace_filter
	# cat /debug/tracing/set_ftrace_filter		# cat set_ftrace_filter
	sys_nanosleep		sys_nanosleep
	# echo 'hrtimer_*' >> /debug/tracing/set_ftrace_filter		# echo 'hrtimer_*' >> set_ftrace_filter
	# cat /debug/tracing/set_ftrace_filter		# cat set_ftrace_filter
	hrtimer_run_queues		hrtimer_run_queues
	hrtimer_run_pending		hrtimer_run_pending
	hrtimer_init		hrtimer_init
	@@ -1677,7 +1728,7 @@ hrtimer_init_sleeper
	The set_ftrace_notrace prevents those functions from being		The set_ftrace_notrace prevents those functions from being
	traced.		traced.

	# echo 'preempt' 'lock' > /debug/tracing/set_ftrace_notrace		# echo 'preempt' 'lock' > set_ftrace_notrace

	Produces:		Produces:

	@@ -1767,13 +1818,13 @@ the effect on the tracing is different. Every read from
	trace_pipe is consumed. This means that subsequent reads will be		trace_pipe is consumed. This means that subsequent reads will be
	different. The trace is live.		different. The trace is live.

	# echo function > /debug/tracing/current_tracer		# echo function > current_tracer
	# cat /debug/tracing/trace_pipe > /tmp/trace.out &		# cat trace_pipe > /tmp/trace.out &
	[1] 4153		[1] 4153
	# echo 1 > /debug/tracing/tracing_enabled		# echo 1 > tracing_enabled
	# usleep 1		# usleep 1
	# echo 0 > /debug/tracing/tracing_enabled		# echo 0 > tracing_enabled
	# cat /debug/tracing/trace		# cat trace
	# tracer: function		# tracer: function
	#		#
	# TASK-PID CPU# TIMESTAMP FUNCTION		# TASK-PID CPU# TIMESTAMP FUNCTION
	@@ -1809,7 +1860,7 @@ number listed is the number of entries that can be recorded per
	CPU. To know the full size, multiply the number of possible CPUS		CPU. To know the full size, multiply the number of possible CPUS
	with the number of entries.		with the number of entries.

	# cat /debug/tracing/buffer_size_kb		# cat buffer_size_kb
	1408 (units kilobytes)		1408 (units kilobytes)

	Note, to modify this, you must have tracing completely disabled.		Note, to modify this, you must have tracing completely disabled.
	@@ -1817,18 +1868,18 @@ To do that, echo "nop" into the current_tracer. If the
	current_tracer is not set to "nop", an EINVAL error will be		current_tracer is not set to "nop", an EINVAL error will be
	returned.		returned.

	# echo nop > /debug/tracing/current_tracer		# echo nop > current_tracer
	# echo 10000 > /debug/tracing/buffer_size_kb		# echo 10000 > buffer_size_kb
	# cat /debug/tracing/buffer_size_kb		# cat buffer_size_kb
	10000 (units kilobytes)		10000 (units kilobytes)

	The number of pages which will be allocated is limited to a		The number of pages which will be allocated is limited to a
	percentage of available memory. Allocating too much will produce		percentage of available memory. Allocating too much will produce
	an error.		an error.

	# echo 1000000000000 > /debug/tracing/buffer_size_kb		# echo 1000000000000 > buffer_size_kb
	-bash: echo: write error: Cannot allocate memory		-bash: echo: write error: Cannot allocate memory
	# cat /debug/tracing/buffer_size_kb		# cat buffer_size_kb
	85		85

	-----------		-----------