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Add process age

RFC PATCH In review Davidlohr Bueso 6 participants 10 messages Jul 23, 2010 – Jul 30, 2010

Subsystems (2)
VFS Proc filesystem
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Share & tools
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Davidlohr Bueso

author
#0 lore raw

RFC PATCH 1/1 Add process age

Hi,

This patch exports a process's age, in seconds, adding a /proc/#/age file.

Thanks,
Davidlohr

Signed-off-by Davidlohr Bueso <[email protected]>
---
 fs/proc/base.c |   19 ++++++++++++++++++-
 1 files changed, 18 insertions(+), 1 deletions(-)
fs/proc/base.c +18 -1
index acb7ef8..a5a4832 100644
@@ -38,13 +38,16 @@
  *  ChangeLog:
  *  10-Mar-2005
  *  10LE Instituto Nokia de Tecnologia - INdT:
- *  A better way to walks through the page table as suggested by Hugh Dickins.
+ *  A better way to walk through the page table as suggested by Hugh Dickins.
  *
  *  Simo Piiroinen <[email protected]>:
  *  Smaps information related to shared, private, clean and dirty pages.
  *
  *  Paul Mundt <[email protected]>:
  *  Overall revision about smaps.
+ *
+ *  2010 - Davidlohr Bueso <[email protected]>:
+ *  Added process age (/proc/#/age), in seconds.
  */
 
 #include <asm/uaccess.h>

@@ -2558,6 +2561,18 @@ static int proc_pid_personality(struct seq_file *m, struct pid_namespace *ns,
 	return 0;
 }
 
+static int proc_pid_age(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task)
+{
+	struct timespec uptime;
+
+	do_posix_clock_monotonic_gettime(&uptime);
+	monotonic_to_bootbased(&uptime);
+	seq_printf(m, "%lu\n", uptime.tv_sec - task->real_start_time.tv_sec);
+
+	return 0;
+}
+
 /*
  * Thread groups
  */

@@ -2575,6 +2590,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 	INF("auxv",       S_IRUSR, proc_pid_auxv),
 	ONE("status",     S_IRUGO, proc_pid_status),
 	ONE("personality", S_IRUSR, proc_pid_personality),
+	ONE("age",        S_IRUSR, proc_pid_age),
 	INF("limits",	  S_IRUSR, proc_pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
 	REG("sched",      S_IRUGO|S_IWUSR, proc_pid_sched_operations),

@@ -2910,6 +2926,7 @@ static const struct pid_entry tid_base_stuff[] = {
 	INF("auxv",      S_IRUSR, proc_pid_auxv),
 	ONE("status",    S_IRUGO, proc_pid_status),
 	ONE("personality", S_IRUSR, proc_pid_personality),
+	ONE("age",        S_IRUSR, proc_pid_age),
 	INF("limits",	 S_IRUSR, proc_pid_limits),
 #ifdef CONFIG_SCHED_DEBUG
 	REG("sched",     S_IRUGO|S_IWUSR, proc_pid_sched_operations),
Signature · 1 line
1.7.0.4
#1 lore raw
Quoted 1 line · Davidlohr Bueso

This patch exports a process's age, in seconds, adding a /proc/#/age file.

What for?

author
#2 lore raw
Quoted 4 lines · Alexey Dobriyan
Quoted 1 line · Davidlohr Bueso

This patch exports a process's age, in seconds, adding a /proc/#/age file.

What for?

I have not found any straight way to get the run time of a processes, without having to interpret the start_time entry in /proc/#/stat and manually subtract the uptime from it.

This small file simply aids the users to obtain the information easier and quicker. Another alternative would be to add an entry in /proc/#/status.

Davidlohr

#3 lore raw
Quoted 3 lines · On Friday 23 of July 2010 22:47:10 Davidlohr Bueso wrote:
Quoted 2 lines · Alexey Dobriyan
Quoted 1 line · Davidlohr Bueso

This patch exports a process's age, in seconds, adding a /proc/#/age

file.

Quoted 6 lines
Quoted 2 lines

What for?

I have not found any straight way to get the run time of a processes, without having to interpret the start_time entry in /proc/#/stat and manually subtract the uptime from it.

Agree. I thing this feature can be useful in some cases.

I have not found better than run something like this:

echo `cat /proc/uptime | awk '{print $1}'` - \
     `cat /proc/$PID/stat | awk '{print $22}'`/100 | bc
Quoted 5 lines

This small file simply aids the users to obtain the information easier and quicker. Another alternative would be to add an entry in /proc/#/status.

Davidlohr

#4 lore raw
In reply to Davidlohr Bueso
Quoted 9 lines · Davidlohr Bueso
Quoted 4 lines · Alexey Dobriyan
Quoted 1 line · Davidlohr Bueso

This patch exports a process's age, in seconds, adding a /proc/#/age file.

What for?

I have not found any straight way to get the run time of a processes, without having to interpret the start_time entry in /proc/#/stat and manually subtract the uptime from it.

That sounds like something an user space program should simply do. Perhaps you can add it as a new optional "-o" field in "ps" ?

-Andi

Signature · 1 line
[email protected] -- Speaking for myself only.
author
#5 lore raw
Quoted 6 lines · Andi Kleen
Quoted 4 lines · Davidlohr Bueso
Quoted 3 lines · Alexey Dobriyan
Quoted 1 line · Davidlohr Bueso

This patch exports a process's age, in seconds, adding a /proc/#/age file.

Quoted 9 lines
Quoted 5 lines
Quoted 1 line

What for?

I have not found any straight way to get the run time of a processes, without having to interpret the start_time entry in /proc/#/stat and manually subtract the uptime from it.

That sounds like something an user space program should simply do. Perhaps you can add it as a new optional "-o" field in "ps" ?

True, but there are also many other no-so-useful files under /proc that can also be replaced by userspace apps.

Davidlohr

#6 lore raw
Quoted 2 lines

True, but there are also many other no-so-useful files under /proc that can also be replaced by userspace apps.

Example?

-andi

Signature · 1 line
[email protected] -- Speaking for myself only.
author
#7 lore raw
Quoted 4 lines · Andi Kleen
Quoted 2 lines

True, but there are also many other no-so-useful files under /proc that can also be replaced by userspace apps.

Example?

Off the top of my head:

/proc/cmdline
Several entries in /proc/#/status, like Name, PPid, Gid, Uid, etc.

I am not criticizing this, I think some repetitive data is good for users. Just showing that other features can also be obtained from userspace.

Davidlohr

#8 lore raw
Quoted 9 lines · Davidlohr Bueso
Quoted 4 lines · Andi Kleen
Quoted 2 lines

True, but there are also many other no-so-useful files under /proc that can also be replaced by userspace apps.

Example?

Off the top of my head:

/proc/cmdline

Are you kidding?

/proc/cmdlines contains lots of info, it is not only used by the kernel, but also used by initramfs (this depends on your distribution).

#9 lore raw
Quoted 7 lines · Américo Wang
Quoted 6 lines · Davidlohr Bueso
Quoted 4 lines · Andi Kleen
Quoted 2 lines

True, but there are also many other no-so-useful files under /proc that can also be replaced by userspace apps.

Example?

Quoted 9 lines
Quoted 3 lines

Off the top of my head:

/proc/cmdline

Are you kidding?

/proc/cmdlines contains lots of info, it is not only used by the kernel, but also used by initramfs (this depends on your distribution).

Silly me, I meant /proc/#/cmdline, in the sense that you can get the command name from the PID in userland.

Davidlohr

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