docs: Procfs -- Document timerfd output

Signed-off-by: Cyrill Gorcunov <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: Andrey Vagin <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>

Author: Cyrill Gorcunov

Documentation/filesystems/proc.txt

@@ -1743,6 +1743,25 @@ pair provide additional information particular to the objects they represent.
 	While the first three lines are mandatory and always printed, the rest is
 	optional and may be omitted if no marks created yet.
 
+	Timerfd files
+	~~~~~~~~~~~~~
+
+	pos:	0
+	flags:	02
+	mnt_id:	9
+	clockid: 0
+	ticks: 0
+	settime flags: 01
+	it_value: (0, 49406829)
+	it_interval: (1, 0)
+
+	where 'clockid' is the clock type and 'ticks' is the number of the timer expirations
+	that have occurred [see timerfd_create(2) for details]. 'settime flags' are
+	flags in octal form been used to setup the timer [see timerfd_settime(2) for
+	details]. 'it_value' is remaining time until the timer exiration.
+	'it_interval' is the interval for the timer. Note the timer might be set up
+	with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
+	still exhibits timer's remaining time.
 
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 Configuring procfs