[ovirt-users] hot plug memory in el7

[Michal Skrivanek]

> On 10 Dec 2015, at 13:16, Gianluca Cecchi <gianluca.cecchi at gmail.com> wrote:
> 
> On Thu, Dec 10, 2015 at 12:24 PM, Michal Skrivanek <mskrivan at redhat.com <mailto: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…):

great!
with 7.2 it should be automatic. I think with Windows it works automatically as well.

> 
> 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?

doesn’t matter much, ovirt-engine, frontend.

> 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?

yeah, these are two separate fields. The suggestion sounds reasonable to me, Roy, thoughts on that?

> Gianluca

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