4:57 p.m.
Hi All,
I have noticed that there is a huge difference between memory reading
obtained from top or free commands, and values displayed on ovirt engine.
"Host "
Example:
Engine Version : *ovirt-engine-3.4.3-1.el6.noarch*
*OS: Centos 6.5_x86_64*
*Used Memory:*
*from free:*
[root@oVirt ~]# free
total used free shared buffers
cached
Mem: 65890412 65609864 280548 0 305408 53759412
from Egnine Webpage:
only 12G is being used.
Is there an explanation for this ?
Please note this is the same on all previous version, the values matches
only after restart of the host then free memory start to vanish by time !
Thanks,
Mohyedeen.
3:50 a.m.
On Wed, Sep 10, 2014 at 11:57:05PM +0300, Mohyedeen Nazzal wrote:
Hi All,
I have noticed that there is a huge difference between memory reading
obtained from top or free commands, and values displayed on ovirt engine.
"Host "
Example:
Engine Version : *ovirt-engine-3.4.3-1.el6.noarch*
*OS: Centos 6.5_x86_64*
*Used Memory:*
*from free:*
[root@oVirt ~]# free
total used free shared buffers
cached
Mem: 65890412 65609864 280548 0 305408 53759412
from Egnine Webpage:
only 12G is being used.
Is there an explanation for this ?
It's a Linux thing. When a file is opened, it is mapped into memory, but
when it is closed Linux does not evict it before memory is released
again. Thus, a long-running active host reaches 0 free mem sooner than
later.
For oVirt GUI, we found this misleading - there, "free" means "how much
memory is available for new VMs to use". Therefore oVirt reports
"buffred" and "cached" memory as free, too.
6:11 a.m.
Hi,
If you look at the full free output you will see another line:
total used free shared buffers cached
Mem: 8057004 7491980 565024 0 234592 2005452
-/+ buffers/cache: 5251936 2805068
The +/- buffers/cache tells you how much memory you will have available after you (the
kernel) clean all buffers and caches.
And that is the number we look at.
--
Martin Sivák
msivak(a)redhat.com
Red Hat Czech
RHEV-M SLA / Brno, CZ
----- Original Message -----
On Wed, Sep 10, 2014 at 11:57:05PM +0300, Mohyedeen Nazzal wrote:
> Hi All,
> I have noticed that there is a huge difference between memory reading
> obtained from top or free commands, and values displayed on ovirt engine.
> "Host "
>
> Example:
> Engine Version : *ovirt-engine-3.4.3-1.el6.noarch*
> *OS: Centos 6.5_x86_64*
>
> *Used Memory:*
> *from free:*
> [root@oVirt ~]# free
> total used free shared buffers
> cached
> Mem: 65890412 65609864 280548 0 305408 53759412
>
> from Egnine Webpage:
>
> only 12G is being used.
>
> Is there an explanation for this ?
It's a Linux thing. When a file is opened, it is mapped into memory, but
when it is closed Linux does not evict it before memory is released
again. Thus, a long-running active host reaches 0 free mem sooner than
later.
For oVirt GUI, we found this misleading - there, "free" means "how much
memory is available for new VMs to use". Therefore oVirt reports
"buffred" and "cached" memory as free, too.
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2 comments
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participants (3)
-
Dan Kenigsberg -
Martin Sivak -
Mohyedeen Nazzal