sysrq key f to trigger OOM manually

sysrq key f to trigger OOM manually

[Vincent Li]

Hi,

not sure if this is the right place, I tried to use echo f >
/proc/sysrq-trigger to manually trigger OOM, the OOM killer is
triggered to kill a process, does it make sense to trigger OOM killer
manually but not actually kill the process, this could be useful to
diagnosis problem without actually killing a process in production
box.

Regards,

Vincent

Re: sysrq key f to trigger OOM manually

[Tetsuo Handa]

On 2019/03/29 6:37, Vincent Li wrote:
> Hi,
> 
> not sure if this is the right place, I tried to use echo f >
> /proc/sysrq-trigger to manually trigger OOM, the OOM killer is
> triggered to kill a process, does it make sense to trigger OOM killer
> manually but not actually kill the process, this could be useful to
> diagnosis problem without actually killing a process in production
> box.

Why not use "/usr/bin/top -o %MEM" etc. ?
Reading from /proc will give you more information than from SysRq.

Re: sysrq key f to trigger OOM manually

[Vincent Li]

On Thu, Mar 28, 2019 at 5:06 PM Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> > On Thu, Mar 28, 2019 at 3:46 PM Tetsuo Handa
> > <penguin-kernel@i-love.sakura.ne.jp> wrote:
> > >
> > > On 2019/03/29 6:37, Vincent Li wrote:
> > > > Hi,
> > > >
> > > > not sure if this is the right place, I tried to use echo f >
> > > > /proc/sysrq-trigger to manually trigger OOM, the OOM killer is
> > > > triggered to kill a process, does it make sense to trigger OOM killer
> > > > manually but not actually kill the process, this could be useful to
> > > > diagnosis problem without actually killing a process in production
> > > > box.
> > >
> > > Why not use "/usr/bin/top -o %MEM" etc. ?
> > > Reading from /proc will give you more information than from SysRq.
> >
> > I am interested to see OOM output including swap entries per process
> > in swap partition and all
> > the other kernel internal virtual memory stats, I find it useful than
> > top or free or /proc/meminfo
> >
>
> Please read http://man7.org/linux/man-pages/man5/proc.5.html and/or
> https://www.kernel.org/doc/Documentation/filesystems/proc.txt .


Thanks, I know I can get lots of information from /proc/<pid>/, but I
like the format/style that OOM dumps since I
don't have to use some kind of script to parse out the /proc/<pid>,
plus, OOM also dumps node/zone/page orders....information all
together, lots of useful information so I can have big picture on the
memory usage of the system.