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From Andrija Panic <andrija.pa...@gmail.com>
Subject Re: KVM host AvailableMemory data is incorrect
Date Tue, 21 Jul 2020 06:47:56 GMT
@li jerry <div8cn@hotmail.com> if ACS tells you your KVM host has 16GB
instead 256GB - that is wrong by all means - and you should try to see
where this comes from (have you upgraded the host in the meantime, or did
anything with it) ?
Even with your break-down of total/cache/buffers etc - your host *should*
has more than 100GB free (buffers + cache = 92GB out of 256B)

You should check you "slab" usage etc - there are other "hiden" RAM usage
beside the buffer and cache.

Best,

On Thu, 16 Jul 2020 at 17:24, Riepl, Gregor (SWISS TXT) <
Gregor.Riepl@swisstxt.ch> wrote:

> Sounds like a calculation bug in cloudstack-agent then.
> You should probably report it on Github.
> ________________________________
> From: li jerry <div8cn@hotmail.com>
> Sent: 15 July 2020 12:08
> To: users@cloudstack.apache.org <users@cloudstack.apache.org>
> Subject: 回复: KVM host AvailableMemory data is incorrect
>
> In my scene
>
> KVM host
> cat /proc/meminfo
> MemTotal=256G
> MemFree=4G
> Cached=12G
> Buffers=80G
>
> When I want to deploy a VM with 32G memory to this host, it prompts that
> the resources are insufficient (mem.overprovisioning.factor=1.0).
>
> CLOUDSTACK tells me that KVMHOST has 16GB of available memory (it does not
> count Buffers). So 16<32, so there is not enough data.
>
>
> But I manually started a VM with 32G memory on KVM HOST, and it succeeded;
> and Buffers/cached/memfree/they were reduced accordingly.
>
> therefore:
> Can we add the memory occupied by Buffers to AvailableMemory and report to
> CLOUDSTACK?
>
> -----邮件原件-----
> 发件人: Riepl, Gregor (SWISS TXT) <Gregor.Riepl@swisstxt.ch>
> 发送时间: 2020年7月15日 17:41
> 收件人: users@cloudstack.apache.org
> 主题: Re: KVM host AvailableMemory data is incorrect
>
> This sounds very familiar...
>
> https://bugzilla.redhat.com/show_bug.cgi?id=1250060
> and they rolled it back in
> https://bugzilla.redhat.com/show_bug.cgi?id=1779609
> because upstream didn't accept their patch.
>
> We had to "fix" our memory monitoring twice because of this.
>
> It's important to *not* calculate buffer/cache memory towards memory
> usage, because the kernel can reclaim this memory whenever there is a need.
> ________________________________
> From: li jerry <div8cn@hotmail.com>
> Sent: 15 July 2020 08:27
> To: users@cloudstack.apache.org <users@cloudstack.apache.org>
> Subject: KVM host AvailableMemory data is incorrect
>
> Hello everyone
>      We use HCI to run CloudStack (KVM+CEPH). After running for a period
> of time, cloudstack reports that HOST has no available memory. But ZABBIX
> monitoring shows that HOST still has a lot of available memory. By
> observing /proc/meminfo on KVM HOST, it is found that most of the memory is
> occupied by Buffers.
>
>      Further analysis of the source code of cloudstack-agent shows that
> the algorithm for cloudstack-agent to obtain AvailableMemory on the host is:
>
> Cached +MemFree -reservedMemory +overCommitMemory
>
> It does not calculate the memory occupied by Buffers.
>
>
> Excuse me, can I mark the memory occupied by Buffers as AvailableMemory?
>
> If not, what is the reason?
>
> Thank you!
>
>
> -       Jerry
>


-- 

Andrija Panić

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