RFR: 8234397: add OS uptime information to os::print_os_info output

[Baesken, Matthias]

Hi David ,  

> 
> Hi Matthias,
> 
> On 21/11/2019 7:24 pm, Baesken, Matthias wrote:
> > Hello,   please review this small addition  to  os::print_os_info  .
> >
> > Currently os::print_os_info outputs various interesting OS information,
> > The output is platforms dependent, on Linux currently the following
> information is printed :
> > distro, uname , some important libversions, some limits, load average,
> memory info, info about /proc/sys , container and virtualization details and
> steal ticks.
> > The OS uptime would be a helpful addition.
> 
> I'd be interested to hear an example of this.
> 

One example that occurred last week  -  my colleague Christoph and me  were browsing through an hs_err  file of a crash on AIX .
When looking into the hs_err  we wanted to know the  uptime because  our latest  fontconfig - patches   (for getting rid of the crash)    needed a reboot too to really work .
Unfortunately we  could not find the info , and we were  disappointed  ( then we noticed the crash is from  OpenJDK and not our internal JVM ).


> > Bug/webrev :
> > https://bugs.openjdk.java.net/browse/JDK-8234397
> > http://cr.openjdk.java.net/~mbaesken/webrevs/8234397.1/
> 
> Can Linux not use the POSIX version?
> 

Unfortunately the posix code does not give the desired result  on Linux (at least on my test machines).

Best regards, Matthias