On 28 Aug 2017, at 13:37, Juan Hernández <jhernand(a)redhat.com&gt; wrote: On 08/28/2017 01:11 PM, Tomáš Golembiovský wrote: > Hi, > there is ongoing effort to change how VDSM collects information about > memory usage from guests. We used to use oVirt guest agent to get the > statistics about free memory, swap usage, etc. This is going to change > and we will use stats provided by VirtIO Balloon driver. [1] This should > not break MOM nor Engine (current or previous versions). > There is however small downside to this change. We will not be able to > fetch information about buffers and caches on Linux guests anymore > (mem_cached and mem_buffers in memoryStats). The corollary of this is > that free memory reported by Engine will also no longer include those > statistics and reported free memory will be really (only) free memory. > I now there will be mixed feelings about this and we would like to get > the information about buffers and caches back to the VDSM. Correctly via > balloon driver statistics. [2] This effort will however take some time. > Tomas > [1] https://gerrit.ovirt.org/#/q/topic:memory-stats > [2] https://lists.nongnu.org/archive/html/qemu-devel/2017-08/msg05239.html Note that this information is currently reported by the engine REST API, so it is part of its contract. Removing it breaks backwards compatibility and causes a regression in this RFE:

[RFE] Report guests Buffered/Cached memory https://bugzilla.redhat.com/1024010 _______________________________________________ Devel mailing list Devel(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/devel

On 08/28/2017 01:42 PM, Michal Skrivanek wrote: > >> On 28 Aug 2017, at 13:37, Juan Hernández <jhernand(a)redhat.com&gt; wrote: >> >> On 08/28/2017 01:11 PM, Tomáš Golembiovský wrote: >>> Hi, >>> there is ongoing effort to change how VDSM collects information about >>> memory usage from guests. We used to use oVirt guest agent to get the >>> statistics about free memory, swap usage, etc. This is going to change >>> and we will use stats provided by VirtIO Balloon driver. [1] This >>> should >>> not break MOM nor Engine (current or previous versions). >>> There is however small downside to this change. We will not be able to >>> fetch information about buffers and caches on Linux guests anymore >>> (mem_cached and mem_buffers in memoryStats). The corollary of this is >>> that free memory reported by Engine will also no longer include those >>> statistics and reported free memory will be really (only) free memory. >>> I now there will be mixed feelings about this and we would like to get >>> the information about buffers and caches back to the VDSM. Correctly >>> via >>> balloon driver statistics. [2] This effort will however take some time. >>> Tomas >>> [1] https://gerrit.ovirt.org/#/q/topic:memory-stats >>> [2] >>> https://lists.nongnu.org/archive/html/qemu-devel/2017-08/msg05239.html >> >> Note that this information is currently reported by the engine REST >> API, so it is part of its contract. Removing it breaks backwards >> compatibility and causes a regression in this RFE: > > we can either declare it deprecated or temporarily report 0 until the > support propagates into qemu-ga > So there will be an interval of time where it will not be reported? Will that affect released versions of the system or it is just something that we will re-add before the next release? It is released versions of the system that I am concerned about. We should not do a release that breaks backwards compatibility. It is completely OK if we break it in between releases. > I think best way forward is to just make it optionally available when > ovirt-guest-agent reports it. > I.e. users will get only part of the information when they run only > qemu-ga, and that’s fine… >

>> >> [RFE] Report guests Buffered/Cached memory >> https://bugzilla.redhat.com/1024010

> On 28 Aug 2017, at 14:02, Juan Hernández <jhernand(a)redhat.com&gt; wrote: > > On 08/28/2017 01:57 PM, Juan Hernández wrote: >> On 08/28/2017 01:42 PM, Michal Skrivanek wrote: >>> >>>> On 28 Aug 2017, at 13:37, Juan Hernández <jhernand(a)redhat.com&gt; wrote: >>>> >>>> On 08/28/2017 01:11 PM, Tomáš Golembiovský wrote: >>>>> Hi, >>>>> there is ongoing effort to change how VDSM collects information about >>>>> memory usage from guests. We used to use oVirt guest agent to get the >>>>> statistics about free memory, swap usage, etc. This is going to change >>>>> and we will use stats provided by VirtIO Balloon driver. [1] This should >>>>> not break MOM nor Engine (current or previous versions). >>>>> There is however small downside to this change. We will not be able to >>>>> fetch information about buffers and caches on Linux guests anymore >>>>> (mem_cached and mem_buffers in memoryStats). The corollary of this is >>>>> that free memory reported by Engine will also no longer include those >>>>> statistics and reported free memory will be really (only) free memory. >>>>> I now there will be mixed feelings about this and we would like to get >>>>> the information about buffers and caches back to the VDSM. Correctly via >>>>> balloon driver statistics. [2] This effort will however take some time. >>>>> Tomas >>>>> [1] https://gerrit.ovirt.org/#/q/topic:memory-stats >>>>> [2] https://lists.nongnu.org/archive/html/qemu-devel/2017-08/msg05239.html >>>> >>>> Note that this information is currently reported by the engine REST API, so it is part of its contract. Removing it breaks backwards compatibility and causes a regression in this RFE: >>> >>> we can either declare it deprecated or temporarily report 0 until the support propagates into qemu-ga >>> >> So there will be an interval of time where it will not be reported? Will that affect released versions of the system or it is just something that we will re-add before the next release? It is released versions of the system that I am concerned about. We should not do a release that breaks backwards compatibility. It is completely OK if we break it in between releases. >>> I think best way forward is to just make it optionally available when ovirt-guest-agent reports it. >>> I.e. users will get only part of the information when they run only qemu-ga, and that’s fine… >>> > > Not sure I understand this. Currently, if I understand correctly, these values are only populated if the ovirt-guest-agent is installed? That is OK (may be worth documenting it). We plan to replace ovirt-guest-agent with qemu-ga in a mandatory way? Or will the user be able to use one or the other? both are mandatory today, though not really enforced, there’s just a “!” next to the VM in the VMs grid. The plan is to switch data retrieval to qemu-ga and make ovirt-ga optional (it’s going to be mandatory for specific purposes, like SSO) > If the user decides to use the ovirt-guest-agent, will we continue to report these statistics? yes, I expect so

Thanks, michal > >>>> >>>> [RFE] Report guests Buffered/Cached memory >>>> https://bugzilla.redhat.com/1024010 >