Question on "Memory" column/field in Virtual Machines list/table in ovirt GUI
Hi, Memory field/column for few of VMs in our ovirt (Compute -> Virtual Machines -> Memory column) shows more than 90%. But, when I checked (from free and also other commands) the actual "used" memory by those VMs, it is less than 60%. What I see (from free -h) is that ovirt seems to be considering both "used" + "buff/cache" memory and is reporting the same in GUI. Isn't it the "available" memory that should be considered, because that is the actual memory available and cache memory is something that is adjusted every time? :~> free -h total used free shared buff/cache available Mem: 15Gi 6.8Gi 724Mi 310Mi 8.1Gi 9.2Gi Swap: 0B 0B 0B Can someone help to answer. Thanks ! /Kishore
What is your VM's OS type ? There is some differences per OS version -> https://www.redhat.com/sysadmin/dissecting-free-command Best Regards, Strahil Nikolov В сряда, 16 септември 2020 г., 11:13:51 Гринуич+3, KISHOR K <smileyface.524@gmail.com> написа: Hi, Memory field/column for few of VMs in our ovirt (Compute -> Virtual Machines -> Memory column) shows more than 90%. But, when I checked (from free and also other commands) the actual "used" memory by those VMs, it is less than 60%. What I see (from free -h) is that ovirt seems to be considering both "used" + "buff/cache" memory and is reporting the same in GUI. Isn't it the "available" memory that should be considered, because that is the actual memory available and cache memory is something that is adjusted every time? :~> free -h total used free shared buff/cache available Mem: 15Gi 6.8Gi 724Mi 310Mi 8.1Gi 9.2Gi Swap: 0B 0B 0B Can someone help to answer. Thanks ! /Kishore _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://www.ovirt.org/privacy-policy.html oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/PAGYQZLHQJIDBX...
Hi, Most of our VMs are SLES SP15 and also few are CentOS 7. But the problem looks to be same for any type of VM. Today, I tried to clear the "buff/cache" memory manually for one of the VM using "sync; echo 3 > /proc/sys/vm/drop_caches" linux command and then I noticed in ovirt GUI that VM's memory usage dropped to 54% from 98%. So, it is clear that ovirt is not considering the actual "available" memory but is considering "free" + "buff/cache" and is reporting the same in ovirt GUI as memory usage %. Isn't this a bug? /Kishore
In Some OS versions it should not be considered a bug. For RH , you can address https://access.redhat.com/solutions/406773 for more details. (For access , you can use a free subscription from developers.redhat.com). Best Regards, Strahil Nikolov В четвъртък, 17 септември 2020 г., 16:00:42 Гринуич+3, KISHOR K <smileyface.524@gmail.com> написа: Hi, Most of our VMs are SLES SP15 and also few are CentOS 7. But the problem looks to be same for any type of VM. Today, I tried to clear the "buff/cache" memory manually for one of the VM using "sync; echo 3 > /proc/sys/vm/drop_caches" linux command and then I noticed in ovirt GUI that VM's memory usage dropped to 54% from 98%. So, it is clear that ovirt is not considering the actual "available" memory but is considering "free" + "buff/cache" and is reporting the same in ovirt GUI as memory usage %. Isn't this a bug? /Kishore _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://www.ovirt.org/privacy-policy.html oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/HNVAIK4ABU72MA...
Hi, I think I already checked that. What I meant (since beginning) was that ovirt is reporting memory usage in GUI same way regardless of CentOS or SLES in our case. My main question is why ovirt is reporting memory usage percentage based on "free" memory but not actually based on "available memory", which is basically sum of "free" and "buff/cache". Buffer/Cache is a temporary memory and that's anyhow gets released for new processes and applications. That means that, ovirt should actually consider the actual available memory left and report usage accordingly in GUI but what we see now is different behavior. I was very worried when I saw the memory usage as 98% and highlighted in red for many of VMs in GUI. But, when I checked the actual used memory by VM, it's always below 50%. Could you clarify how can this behavior from ovirt be OS specific? I hope I explained the issue clearly or let me know if it is still unclear. Thanks in advance. /Kishore
For some OS versions , the oVirt's behavior is accurate , but for other versions it's not accurate. I think that it is more accurate to say that oVirt improperly calculates memory for SLES 15/openSUSE 15. I would open a bug at bugzilla.redhat.com . Best Regards, Strahil Nikolov В понеделник, 21 септември 2020 г., 15:15:42 Гринуич+3, KISHOR K <smileyface.524@gmail.com> написа: Hi, I think I already checked that. What I meant (since beginning) was that ovirt is reporting memory usage in GUI same way regardless of CentOS or SLES in our case. My main question is why ovirt is reporting memory usage percentage based on "free" memory but not actually based on "available memory", which is basically sum of "free" and "buff/cache". Buffer/Cache is a temporary memory and that's anyhow gets released for new processes and applications. That means that, ovirt should actually consider the actual available memory left and report usage accordingly in GUI but what we see now is different behavior. I was very worried when I saw the memory usage as 98% and highlighted in red for many of VMs in GUI. But, when I checked the actual used memory by VM, it's always below 50%. Could you clarify how can this behavior from ovirt be OS specific? I hope I explained the issue clearly or let me know if it is still unclear. Thanks in advance. /Kishore _______________________________________________ Users mailing list -- users@ovirt.org To unsubscribe send an email to users-leave@ovirt.org Privacy Statement: https://www.ovirt.org/privacy-policy.html oVirt Code of Conduct: https://www.ovirt.org/community/about/community-guidelines/ List Archives: https://lists.ovirt.org/archives/list/users@ovirt.org/message/HAJ6TT74U33FAF...
Ok, May I know why you think it's only a bug in SLES?. As I said before, ovirt is behaving the same way even for CentOS7 VMs. I am attaching the details again here below. One of running CentOS VM memory details are as below. [centos@centos-vm1 ~]$ free -m total used free shared buff/cache available Mem: 7816 1257 176 386 6383 5874 Swap: 0 0 0 Here, out of total allocated memory of 7816 MB, we can see that total actual available memory is 5874 MB and the actual used memory is just 1257 MB, excluding buff/cache. But in ovirt GUI, memory usage field/column for above VM (Compute -> Virtual Machines and then Select VM and Check Memory field/Column) shows usage as 98%. That means that, it says only 2% memory (considering 176 MB) is free and 98% is used (considering used + buff/cache i.e. 1257 MB + 6383 MB). My question is why ovirt is treating buff/cache memory as used memory and why is not reporting memory usage just based on actual used memory?
Ok, May I know why you think it's only a bug in SLES?. I never claimed it is a bug in SLES, but a bug in Ovirt detecting proper memory usage in SLES. The behaviour you observe was normal for RHEL6/CentOS6/SLES11/openSUSE and bellow , so it is normal for some OSes.In my oVirt 4.3.10 , I see that the entry there is "SLES11+" , but I believe that it is checking the memory on SLES15 , just as if it is a SLES11.
As I said before, ovirt is behaving the same way even for CentOS7 VMs. I am attaching the details again here below. Most probably oVirt is checking memory the RHEL6 style , which is not the correct one.
My question is why ovirt is treating buff/cache memory as used memory and why is not reporting memory usage just based on actual used memory? Most probably it is a bug :D , every software has some. I would recommend you to open a bug in the bugzilla.redhat.com for each OS type (for example 1 for SLES/openSUSE and 1 for EL7/EL8-based).
Best Regards, Strahil Nikolov
Hello, Sorry, yes i meant a bug in ovirt with SLES, not in SLES :). Now, I understand all the details. Thanks a lot ! I will then open a bug as suggested, never did it before but hope it will be easy :) /Kishore
participants (2)
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KISHOR K -
Strahil Nikolov