10:31 p.m.
Hi,
while testing oVirt 3.5 RC I've came across this cluster setting:
Optimization -> KSM control -> [X] Enable KSM
I guess it's related to Kernel Same-page Merging.
Since KSM is a bad idea in my case (really slow CPUs), I've disabled
this Cluster setting, expecting oVirt to disable KSM on each oVirt Node.
But KSM is still running and consuming a lot CPU.
1) What is the expected result for this setting?
2) And how do I completely and permanentely disable KSM on oVirt Nodes?
Regards
- Frank
11:08 p.m.
On 10/09/2014 04:31 PM, Frank Wall wrote:
Hi,
while testing oVirt 3.5 RC I've came across this cluster setting:
Optimization -> KSM control -> [X] Enable KSM
I guess it's related to Kernel Same-page Merging.
Since KSM is a bad idea in my case (really slow CPUs), I've disabled
this Cluster setting, expecting oVirt to disable KSM on each oVirt Node.
But KSM is still running and consuming a lot CPU.
1) What is the expected result for this setting?
It will have effect next host change to Up state (i.e. from Maintenance
or from a reboot). Anyway, you can force the policy to have effect on
the fly: select the cluster, click in Hosts sub-tab, select the host(s)
and click "Sync MOM Policy".
2) And how do I completely and permanentely disable KSM on oVirt
Nodes?
This setting is permanent.
Regards
- Frank
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2:06 p.m.
On Thu, Oct 09, 2014 at 05:08:56PM -0300, Amador Pahim wrote:
On 10/09/2014 04:31 PM, Frank Wall wrote:
> while testing oVirt 3.5 RC I've came across this cluster setting:
> Optimization -> KSM control -> [X] Enable KSM
> [...]
> But KSM is still running and consuming a lot CPU.
It will have effect next host change to Up state (i.e. from Maintenance
or from a reboot). Anyway, you can force the policy to have effect on
the fly: select the cluster, click in Hosts sub-tab, select the host(s)
and click "Sync MOM Policy".
Unfortunately, it doesn't work for me. Everytime I restart vdsmd
it will automatically start ksm again (and ksmd starts consuming CPU).
I couldn't find anything ksm-related in vdsm.log. Is there a way to
debug this? I strongly assume that the KSM Custer setting isn't working
as expected.
FWIW, I've just upgraded to oVirt 3.5.0 GA and test this setting again.
Regards
- Frank
6:42 p.m.
----- Original Message -----
From: "Frank Wall" <fw(a)moov.de>
To: "Amador Pahim" <apahim(a)redhat.com>
Cc: users(a)ovirt.org
Sent: Sunday, October 19, 2014 2:06:50 PM
Subject: Re: [ovirt-users] Cluster settings: "KSM Control" not working?
On Thu, Oct 09, 2014 at 05:08:56PM -0300, Amador Pahim wrote:
>
> On 10/09/2014 04:31 PM, Frank Wall wrote:
> > while testing oVirt 3.5 RC I've came across this cluster setting:
> > Optimization -> KSM control -> [X] Enable KSM
> > [...]
> > But KSM is still running and consuming a lot CPU.
>
> It will have effect next host change to Up state (i.e. from Maintenance
> or from a reboot). Anyway, you can force the policy to have effect on
> the fly: select the cluster, click in Hosts sub-tab, select the host(s)
> and click "Sync MOM Policy".
Unfortunately, it doesn't work for me. Everytime I restart vdsmd
it will automatically start ksm again (and ksmd starts consuming CPU).
I couldn't find anything ksm-related in vdsm.log. Is there a way to
debug this? I strongly assume that the KSM Custer setting isn't working
as expected.
FWIW, I've just upgraded to oVirt 3.5.0 GA and test this setting again.
Regards
- Frank
Hi Frank,
KSM is controlled by MoM, which gets its policy from the engine through
VDSM. MoM will call ksm directly as needed when needed. If you choose
to disable it the policy needs to get updated.
Can you please check your mom logs and see if there are any errors there?
10:48 p.m.
Hi Doron,
On Sun, Oct 19, 2014 at 11:42:47AM -0400, Doron Fediuck wrote:
KSM is controlled by MoM, which gets its policy from the engine
through
VDSM. MoM will call ksm directly as needed when needed. If you choose
to disable it the policy needs to get updated.
Can you please check your mom logs and see if there are any errors there?
I wasn't aware of mom.log, thanks! :-) After another host reboot
and a manual "Sync MOM Policy" it seems like the setting finally came
through:
2014-10-19 15:57:18,211 - mom.Controllers.KSM - INFO - Updating KSM configuration:
pages_to_scan:64 run:0 sleep_millisecs:10
Now the ksmd process is still there, but it remains idle.
I've tried this multiple times before upgrading to 3.5.0 GA
today. Maybe it was broken between RC and GA.
I'll keep an eye on this and open a BZ in case the setting will
change again.
Regards
- Frank
5:22 p.m.
On 10/19/2014 04:48 PM, Frank Wall wrote:
Hi Doron,
On Sun, Oct 19, 2014 at 11:42:47AM -0400, Doron Fediuck wrote:
> KSM is controlled by MoM, which gets its policy from the engine through
> VDSM. MoM will call ksm directly as needed when needed. If you choose
> to disable it the policy needs to get updated.
> Can you please check your mom logs and see if there are any errors there?
I wasn't aware of mom.log, thanks! :-) After another host reboot
and a manual "Sync MOM Policy" it seems like the setting finally came
through:
2014-10-19 15:57:18,211 - mom.Controllers.KSM - INFO - Updating KSM configuration:
pages_to_scan:64 run:0 sleep_millisecs:10
Now the ksmd process is still there, but it remains idle.
Indeed ksmd process will always be there. The ultimate place to check
whether it's working or not is /sys/kernel/mm/ksm/run file. "1" for
running and "0" for sleeping. mom.log is reflecting its value and MoM
process will change it as needed.
I've tried this multiple times before upgrading to 3.5.0 GA
today. Maybe it was broken between RC and GA.
I'll keep an eye on this and open a BZ in case the setting will
change again.
Regards
- Frank
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5 comments
3 participants
participants (3)
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Amador Pahim -
Doron Fediuck -
Frank Wall