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Re: Bookworm system not responding on high memory usage



Timothy M Butterworth <timothy.m.butterworth@gmail.com> writes:

> On Fri, Mar 10, 2023 at 7:57 PM Xiyue Deng <manphiz@gmail.com> wrote:
>
>  Hi,
>
>  I have an AMD64 system[1] that has been running fine on Bullseye for a
>  few years, and recently following the soft freeze on Bookworm I upgraded
>  my system to try it out, and the system has been frequently losing
>  response.  Initially I thought it was because of some issue of my
>  qemu-based Win11 virtual machine as it happens most frequently when it
>  was running and filed a bug report[2].  But then it happened again
>  without it running because some other program had slowly used up most of
>  the memory again, though not as frequently as the VM was running.
>
>  Now in retrospect, when I was using Bullseye the total memory was also
>  mostly used up most of the time, with a few hundreds of megabytes
>  reported as free and a few Gigs reported as cache, and it has been
>  running fine.  I'm not sure what has changed in Bookworm and having to
>  manually restart the machine is a pretty annoying and unpleasant
>  experience.
>
>  Does anyone seeing a similar problem as well?  What can I do to avoid
>  this?  Any suggest is welcome.
>
>  Thanks in advance.
>
> Open the command prompt and run `su` to switch user to root. Then run `sync && echo 1 > /proc/sys/vm/drop_caches` as
> root. This will write RAM caches to the hard drive to free up memory. You have to run this as root as sudo, my preferred
> method, returns a permission disabled error.

Thanks for the tip!  I'll try it out.

>  
>  
>  [1] System info from inxi:
>  CPU: 8-core AMD Ryzen 9 5900HX with Radeon Graphics (-MT MCP-)
>  speed/min/max: 1199/1200/4679 MHz Kernel: 6.1.0-5-amd64 x86_64 Up: 7m
>  Mem: 4844.4/31521.3 MiB (15.4%) Storage: 476.94 GiB (54.5% used) Procs: 535
>  Shell: Bash inxi: 3.3.25
>
> Your system has 32 GB of RAM, it should not be getting used up. Run `free -h` What desktop are you using: KDE, GNOME,
> LXQT etc? Are you using Wayland or X11? It looks like you have a memory leak in one of your applications. Try running
> `top` and press `m` to sort by memory utilization.

I actually have a cronjob that runs every 5 minutes and collects memory
usage.  As I mentioned, it usually happens when I use qemu (see [1] for
free and [2] for top).  At another time it happened when deluge is
leaking memory (see [3] for free [4] for top).

Interestingly as you can see, in all such cases, even though the free
amount is low, the buff/cache is still pretty large so the system is not
really overloaded.  Plus, on Bullseye such memory usage also happens all
the time and this never happened.  I was suspecting that maybe the
kernel is panicking when memory hits certain limit, but I don't see it
in kern.log or syslog.

Any suggestion to restore to Bullseye status is appreciated.  Thanks in
advance!


[1] `free -h` when using qemu:
               total        used        free      shared  buff/cache   available
Mem:            30Gi        14Gi       258Mi       216Mi        17Gi        16Gi
Swap:          979Mi        80Mi       899Mi

[2] `top` sorted by memory when using qemu:
top - 16:10:05 up  1:29, 11 users,  load average: 1.83, 1.86, 2.06
Tasks: 494 total,   1 running, 493 sleeping,   0 stopped,   0 zombie
%Cpu(s):  8.3 us,  8.3 sy,  0.0 ni, 75.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st 
MiB Mem :  31522.7 total,    257.2 free,  14430.8 used,  17504.1 buff/cache     
MiB Swap:    980.0 total,    899.5 free,     80.5 used.  17091.9 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
  10131 libvirt+  20   0   11.2g   8.1g  26140 S 213.3  26.2  75:08.67 qemu-sy+
   6547 xiyueden  20   0 4432172   1.4g 207312 S   0.0   4.5   1:53.44 thunder+
...

[3] `free -h` when using deluge:
               total        used        free      shared  buff/cache   available
Mem:            30Gi        12Gi       1.9Gi       219Mi        17Gi        18Gi
Swap:          979Mi       2.2Mi       977Mi

[4] `top` sorted by memory when using deluge:
top - 10:40:05 up 3 days, 17:11, 11 users,  load average: 1.25, 1.22, 1.20
Tasks: 492 total,   1 running, 490 sleeping,   0 stopped,   1 zombie
%Cpu(s): 25.0 us,  0.0 sy,  0.0 ni, 75.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st 
MiB Mem :  31521.3 total,   1909.2 free,  12762.9 used,  17529.7 buff/cache     
MiB Swap:    980.0 total,    977.7 free,      2.2 used.  18758.4 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND
   7287 xiyueden  20   0 9030940   6.6g 503076 S   0.0  21.3  97:11.62 deluge-+
   5271 xiyueden  20   0 4581328   1.6g 191000 S   6.7   5.2 108:23.57 thunder+
...

>
> Tim
>
>  
>  [2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1032400
>
>  -- 
>  Manphiz


-- 
Manphiz


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