[Users] Custom settings for Kernel Same-page Merging (KSM)?
Hi, recently I've noticed that ksmd is using quite a lot CPU on my oVirt node. While I have plenty RAM, my CPU is way slow. Thus ksmd is eating up the most limited ressource here. Is it supported to use custom settings for ksmd? I've noticed that it is handled by MoM: /etc/vdsm/mom.d/03-ksm.policy. May I just change some settings here, or is there a tuning parameter in oVirt engine? Couldn't find a matching one with engine-config. I'd like to use a higher value for sleep_millisecs to reduce CPU usage (with the possible side effect of higher RAM usage). Thanks - Frank
Hi Frank, we do not currently have anything in the engine that would allow you to do this. If you create an oVirt RFE bug for it it would make it easier for us to add the feature and track the progress. However you can update the policy file you found to accomplish this. Just set (defvar ksm_sleep_ms_baseline 10) to a higher value and do not forget to properly restart VDSM when you do. Regards -- Martin Sivák msivak@redhat.com Red Hat Czech RHEV-M SLA / Brno, CZ ----- Original Message -----
Hi,
recently I've noticed that ksmd is using quite a lot CPU on my oVirt node. While I have plenty RAM, my CPU is way slow. Thus ksmd is eating up the most limited ressource here.
Is it supported to use custom settings for ksmd? I've noticed that it is handled by MoM: /etc/vdsm/mom.d/03-ksm.policy. May I just change some settings here, or is there a tuning parameter in oVirt engine? Couldn't find a matching one with engine-config.
I'd like to use a higher value for sleep_millisecs to reduce CPU usage (with the possible side effect of higher RAM usage).
Thanks - Frank _______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
Hi Martin, On 2013-11-04 11:12, Martin Sivak wrote:
we do not currently have anything in the engine that would allow you to do this. If you create an oVirt RFE bug for it it would make it easier for us to add the feature and track the progress.
good advice, here we go: https://bugzilla.redhat.com/show_bug.cgi?id=1026294 I wasn't sure if I should file a bug for vdsmd or ovirt-engine, so maybe someone needs to reclassify this PR.
However you can update the policy file you found to accomplish this. Just set (defvar ksm_sleep_ms_baseline 10) to a higher value and do not forget to properly restart VDSM when you do.
Thanks, I've already thought of doing this as a temporary workaround, but wanted to make sure that it's not customizable yet. So I'm going to hardcode my preferred value on next maintenance. Thanks - Frank
On 11/04/2013 01:24 PM, Frank Wall wrote:
Hi Martin,
On 2013-11-04 11:12, Martin Sivak wrote:
we do not currently have anything in the engine that would allow you to do this. If you create an oVirt RFE bug for it it would make it easier for us to add the feature and track the progress.
good advice, here we go: https://bugzilla.redhat.com/show_bug.cgi?id=1026294
I wasn't sure if I should file a bug for vdsmd or ovirt-engine, so maybe someone needs to reclassify this PR.
However you can update the policy file you found to accomplish this. Just set (defvar ksm_sleep_ms_baseline 10) to a higher value and do not forget to properly restart VDSM when you do.
Thanks, I've already thought of doing this as a temporary workaround, but wanted to make sure that it's not customizable yet. So I'm going to hardcode my preferred value on next maintenance.
I'm more concerned by the fact ksm consumed RAM supposedly before memory usage was >80%.
Hi, any update why this may have happened? Am 04.11.2013 21:02, schrieb Itamar Heim:
I'm more concerned by the fact ksm consumed RAM supposedly before memory usage was >80%.--
Mit freundlichen Grüßen / Regards Sven Kieske Systemadministrator Mittwald CM Service GmbH & Co. KG Königsberger Straße 6 32339 Espelkamp T: +49-5772-293-100 F: +49-5772-293-333 https://www.mittwald.de Geschäftsführer: Robert Meyer St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
Hi Sven, the reason is that the rule is a bit more complex now. KSM is started when free memory drops below 20% or if the ksm_shareable value gets above 80% of available memory. the relevant rule in the policy is: (defvar ksm_pressure_threshold (* Host.mem_available ksm_free_percent)) (defvar ksm_committed Host.ksm_shareable) (if (and (> (+ ksm_pressure_threshold ksm_committed) Host.mem_available) (< (Host.StatAvg "mem_free") ksm_pressure_threshold)) Regards -- Martin Sivák msivak@redhat.com Red Hat Czech RHEV-M SLA / Brno, CZ ----- Original Message -----
Hi,
any update why this may have happened?
Am 04.11.2013 21:02, schrieb Itamar Heim:
I'm more concerned by the fact ksm consumed RAM supposedly before memory usage was >80%.--
Mit freundlichen Grüßen / Regards
Sven Kieske
Systemadministrator Mittwald CM Service GmbH & Co. KG Königsberger Straße 6 32339 Espelkamp T: +49-5772-293-100 F: +49-5772-293-333 https://www.mittwald.de Geschäftsführer: Robert Meyer St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen _______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
participants (4)
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Frank Wall -
Itamar Heim -
Martin Sivak -
Sven Kieske