[ovirt-users] hot plug memory in el7

[Gianluca Cecchi]

On Thu, Dec 10, 2015 at 12:24 PM, Michal Skrivanek <mskrivan at redhat.com>
wrote:

>
>
> >
> > Yes, CentOS 7.1 updated up to a couple of days ago.
>
> Can you try 7.2? I don’t remember exactly but it may be that in earlier
> guests it’s not automatic. Check some tips for onlining memory explicitly
>
> 5.2. How to online memory
>  ------------
> Even if the memory is hot-added, it is not at ready-to-use state.
> For using newly added memory, you have to "online" the memory block.
>
> For onlining, you have to write "online" to the memory block's state file
> as:
>
> % echo online > /sys/devices/system/memory/memoryXXX/state
>
>

Hello,
with your suggestions it worked as expected, without updating any packages
in VM 7.1 guest (I seemed to remember that the forced online operation
should not be necessary any more...):

Starting state with 10Gb of ram inside the VM
[root at racclient1 ~]# ll -d  /sys/devices/system/memory/memory* | wc -l
80

slots defined:
0 --> 23
32 --> 87

Increase from web gui memory from 10240 to 12288

I see this in messages as expected

Dec 10 12:59:32 racclient1 kernel: init_memory_mapping: [mem
0x2c0000000-0x33fffffff]

In /sys/devices/system/memory I see 16 new memoryxx directories (probably
each one addressing 128Mb...)

88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103

They have indeed been added but are offline, eg

latest previous one:
[root at racclient1 ~]# cat /sys/devices/system/memory/memory87/state
online

first newly added one:
[root at racclient1 ~]# cat /sys/devices/system/memory/memory88/state
offline

[root at racclient1 ~]# cat /sys/devices/system/memory/memory87/online
1
[root at racclient1 ~]# cat /sys/devices/system/memory/memory88/online
0

put online the new segments:
[root at racclient1 ~]# for i in $(seq 88 103)
> do
> echo online > /sys/devices/system/memory/memory${i}/state
> done

Memory has been increased now, also from inside the OS.

[root at racclient1 ~]# free
              total        used        free      shared  buff/cache
available
Mem:       12334428      222080    11934044        8480      178304
 12019544


NOTE: no new entries after online memory, neither in messages file nor in
dmesg output.

Questions:
1) which component to bugzilla against for message confusing window of the
gui?
2) Initially I see that my VM (in webadmin gui) has 8Gb of defined memory
AND 8Gb of "Physical Memory Guaranteed".
After increasing memory, the second one remains the same and doesn't change
even after shutdown / Power on.
I think it could be an enhancement to ask the user if he/she wants to
change it too, instead of manually go through
Edit --> resource allocation --> memory allocation screen
If seen as a agreed enhancement, which components to bugzilla against for
RFE?
Gianluca
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