Subject: Re: [vserver] Small flaw inside guest on kernel 4.1.13-vs2.3.8.3
From: Herbert Poetzl <herbert@13thfloor.at>
Date: Fri, 19 Aug 2016 15:06:00 +0200

On Fri, Aug 19, 2016 at 12:26:15PM +0200, Urban Loesch wrote:
> Hi Herbert,

Hey Urban!

> I tried kernel 4.1.27 with patch 2.3.8.5.2.
> Now the "free" command inside the guest shows the 
> assigned amount of memory to the guest.

> But know it show always the same amount, also on 
> line "-/+ buffers/cache":

You mean the buffers/cache information follows the
memory information regardless of the actual usage?

> ...
> linux-image-4.1.27-vs2.3.8.5.2-em64t-efigpt_1_amd64
> ...
> root@dbserver:/ # free
>              total       used       free     shared    buffers     cached
> Mem:      50331648   29124200   21207448          0          0          0
> -/+ buffers/cache:   29124200   21207448
> Swap:      4194304     171660    4022644
> ...

> Now it seems that the guest uses it's hole assigned 
> memory and this triggers my monitoring.

Hmm, I don't see that, there is rougly the same
amount of free memory as used memory in your example,
so it looks like half the assigned memory is used.

Please elaborate ...

Best,
Herbert

> Thanks
> Urban

> Am 02.02.2016 um 10:34 schrieb Herbert Poetzl:
>> On Mon, Feb 01, 2016 at 03:02:28PM +0100, Urban Loesch wrote:
>>> Hi,

>> Hey Urban!

>>> there is a small flaw inside the guest on kernel 4.1.13-vs2.3.8.3.

>>> The "free" command shows the full memory of a host and not the
>>> assigned amount, even if the "flags" file in
>>> "/etc/vservers/$VSNAME/flags" is set like this:
>>> ...
>>> VIRT_MEM
>>> VIRT_CPU
>>> VIRT_LOAD
>>> ...

>>> Some other details:
>>> kernel:  4.1.13-vs2.3.8.3
>>> util-vserver:
>>> ii  libvserver0        0.30.216-pre3120-jessie0.1-1 amd64 dynamic 
>>> libraries for util-vserver
>>> ii  util-vserver       0.30.216-pre3120-jessie0.1-1 amd64 utilities for 
>>> managing Linux-VServer guests
>>> ii  util-vserver-build 0.30.216-pre3120-jessie0.1-1 amd64 tools which can 
>>> be used to build vservers
>>> ii  util-vserver-core  0.30.216-pre3120-jessie0.1-1 amd64 core utilities 
>>> of util-vserver
>>> ii  util-vserver-sysv  0.30.216-pre3120-jessie0.1-1 amd64 initscripts for 
>>> util-vserver

>>> Host-OS:	Debian Jessie
>>> Guest-OS:	Debian etch oder higher. Also Jessie is affected.

>>> The "top" command shows the correct assigned cpu eg. 14-15.
>>> ...
>>> top - 14:59:26 up 2 days, 20:25,  0 users,  load average: 0.05, 0.07, 0.02
>>> Tasks:  16 total,   2 running,  14 sleeping,   0 stopped,   0 zombie
>>> Cpu14 :  1.7%us,  0.0%sy,  0.0%ni, 98.3%id,  0.0%wa,  0.0%hi,  0.0%si,  
>>> 0.0%st
>>> Cpu15 :  1.5%us,  0.0%sy,  0.0%ni, 98.5%id,  0.0%wa,  0.0%hi,  0.0%si,  
>>> 0.0%st
>>> Mem:  32935924k total, 32745520k used,   190404k free,   248248k buffers
>>> Swap:  7811068k total,     8620k used,  7802448k free,        0k cached

>>>  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  P COMMAND
>>> ...

>> Thanks for reporting, but this is known, as the relevant
>> code in the 4.1.x patches has not been adapted to the
>> changes in the kernel (i.e. it is disabled for now)

>>> All limits are assigned with cgroups.
>>> Have you some idea how I can fix this?

>> By adapting the relevant code (it is still there but
>> disabled for now) to the changes in the kernel.

>>> As I just said, this is not a real error, but only a flaw
>>> that bothers me.

>> Yeah, you are probably not the only one who misses this
>> feature, I will see what I can do to get it working again.

>> All the best,
>> Herbert

>>> Thanks and regards
>>> Urban