[pkg-lxc-devel] Bug#885542: lxcfs: virtualizing the btime field of /proc/stat screws up process start times

[Paul Slootman]

Source: lxcfs
Version: 2.0.7-1
Severity: normal
Tags: upstream

As reported here: https://github.com/lxc/lxd/issues/3517
which points to https://github.com/lxc/lxcfs/issues/164 (where is stated
that virtualizing the btime field has been reverted due to
https://github.com/lxc/lxcfs/issues/189), I'm experiencing wrong stimes 
for processes.

As I find having accurate start times of processes far more important
than having an accurate uptime counter for my containers, as do other
people as well apparently, I would like to see this reverted until a
better solution for the btime field /uptime is found.

# lxc-attach -n bla
bla# ls -l /run/apache2/apache2.pid 
-rw-r--r-- 1 root root 5 Dec 27 14:15 /run/apache2/apache2.pid
bla# ps -fp `cat /run/apache2/apache2.pid`
UID        PID  PPID  C STIME TTY          TIME CMD
root      5691     1  0 17:29 ?        00:00:01 /usr/sbin/apache2 -k start
bla# uptime
 21:35:21 up 3 days,  2:57,  0 users,  load average: 0.15, 0.13, 0.17
bla# exit 
host# uptime
  21:35:33 up 3 days,  7:00,  5 users,  load average: 0.13, 0.13, 0.16

You can see the difference in time between starting the host and the
container is the difference between the time shown by ps and the actual
start time of the process.


Thanks,
Paul

-- System Information:
(reported from a different system as the LXC system has no email as yet)