I got a 3 TB host (physical) with Oracle without Traditional Hugepages. The DB will work
even without hugepages... but how much memory will be lost - that's another story.
Disable the transparent Huge Pages and check this documentation - should be valid for
oVirt 4.3 and OLVM 4.3 as they share the same source:
https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.3/...
Best Regards,
Strahil Nikolov
В сряда, 29 септември 2021 г., 15:20:54 ч. Гринуич+3, Tommy Sway <sz_cuitao(a)163.com>
написа:
I’am 4.3, but the memory of the VM and the SGA is large , 32GB, so the vm should set the
traditional hugepage for the database SGA.
I don't know how to set up a large page on a KVM host.
Because if I make it a traditional big page, how big should I make it? Will non-VM SGA
usage of many VMs be affected?
After all, not all memory used by QEMU needs to be HugePage, and traditional large page
memory needs to be used by specific code calls and is not transparent.
These are all questions.
From: users-bounces(a)ovirt.org <users-bounces(a)ovirt.org> On Behalf Of Strahil Nikolov
via Users
Sent: Wednesday, September 29, 2021 5:39 PM
To: Tommy Sway <sz_cuitao(a)163.com>; 'users' <users(a)ovirt.org>
Subject: [ovirt-users]Re: 回复: Re: About the vm memory limit
If you are on 4.3 -> disable transparent hugepages both Hypervisor and VM.
If you are using 4.4 -> disable transparent hugepages and also cobfigure regular huge
pages.
Best Regards,
Strahil Nikolov
> On Wed, Sep 29, 2021 at 5:34, Tommy Sway
> <sz_cuitao(a)163.com> wrote:
> From the Oracle OLVM support:
>
> Configuring the Hugepages for guest VMs should be suffice, however, it needs the KVM
hosts too configured with the Hugepages.
> Since, if it not you may end with issues while staring the guest VMs.
>
> I really don't know what to do now.
>
>
>
>
>
> -----Original Message-----
> From: users-bounces(a)ovirt.org <users-bounces(a)ovirt.org> On Behalf Of Strahil
Nikolov via Users
> Sent: Tuesday, September 28, 2021 3:39 PM
> To: 'users' <users(a)ovirt.org>; Tommy Sway <sz_cuitao(a)163.com>
> Subject: [ovirt-users]Re: 回复: Re: About the vm memory limit
>
> I think that if you run VMs with Databases, you must disable transparent huge pages
on Hypervisour level and on VM level. Yet, if you wish you can use regular huge pages on
VM level.
>
> Best Regards,
> Strahil Nikolov
>
>
>
>
>
>
> В вторник, 28 септември 2021 г., 09:21:09 ч. Гринуич+3, Tommy Sway
<sz_cuitao(a)163.com> написа:
>
>
>
>
>
>
> What problem will appear if I use the default transparent huge page enabled mode for
physical hosts, but configure traditional huge page memory on the virtual machine for
database SGA ?
> Or is it better to disable transparent huge page on physical machines and still use
traditional huge page memory on virtual machines?
>
> Which one is prefer ?
>
>
> From: users-bounces(a)ovirt.org <users-bounces(a)ovirt.org> On Behalf Of Strahil
Nikolov via Users
> Sent: Tuesday, September 28, 2021 12:05 AM
> To: tommy <sz_cuitao(a)163.com>; 'users' <users(a)ovirt.org>
> Subject: [ovirt-users]Re: 回复: Re: About the vm memory limit
>
>
https://docs.oracle.com/en/database/oracle/oracle-database/19/ladbi/disab...
>
>
https://access.redhat.com/solutions/1320153 (requires RH dev subscription or other
type of subscription) -> In short add 'transparent_hugepage=never' to the
kernel params
>
> SLES11/12/15 ->
https://www.suse.com/c/sles-1112-os-tuning-optimisation-guide-part-1/
>
>
> Best Regards,
> Strahil Nikolov
>
>
>
>
>
>> On Mon, Sep 27, 2021 at 16:33, tommy <sz_cuitao(a)163.com> wrote:
>> thank you!
>>
>> and how to get the config info of Transparent huge pages and how to
>> disable it?
>>
>>
>>
>>
>>
>> 发自我的华为手机
>>
>>
>> -------- 原始邮件 --------
>> 发件人: Strahil Nikolov <hunter86_bg(a)yahoo.com>
>> 日期: 2021年9月27日周一 21:13
>> 收件人: 'users' <users(a)ovirt.org>, Tommy Sway
<sz_cuitao(a)163.com>
>> 主 题: Re: [ovirt-users] Re: About the vm memory limit>> Transparent huge
pages are enabled by default, so you need to stop >> them.I would use huge pages on
both host and VM, but theoretically it >> shouldn't be a problem running a VM
with enabled HugePages without >> configuring on Host.Best Regards,Strahil NikolovВ
събота, 25 >> септември 2021 г., 15:25:10 ч. Гринуич+3, Tommy Sway >>
<sz_cuitao(a)163.com> написа: transparent huge pages are not used on vm >> and
physical host. But, can I enable hugepage memory on virtual >> machines but not on
a physical machine?For database running on vm, >> and it needs to config hugepage.
From: Strahil Nikolov >> <hunter86_bg(a)yahoo.com> Sent: Saturday, September 25,
2021 5:32 PMTo: >> Tommy Sway <sz_cuitao(a)163.com>Subject: Re: [ovirt-users]
About the vm >> memory limit It depends on the numa configuration of the host. If
you >> have 256G per CPU, it's best to stay into that range. Also, consider
>> disabling transparent huge pages on the host & VM. Since 4.4 Regular >>
Huge Pages (do not confuse them with THP) can be used on the >> Hypervisors, while
on 4.3 there were some issues but I can't provode >> any details. Best
Regards,Strahil Nikolov> On Fri, Sep 24, 2021 at >> 6:40, Tommy Sway>
<sz_cuitao(a)163.com> wrote:> I would like to ask if >> there is any limit on
the memory size of virtual machines, or >> performance curve or something like
that?> As long as there is memory >> on the physical machine, the more virtual
machines the better?> > In >> our usage scenario, there are many virtual
machines with databases, >> and their memory varies greatly. > For some virtual
machines, 4G >> memory is enough, while for some virtual machines, 64GB memory is
>> needed.> > I want to know what is the best use of memory for a >>
virtual machine, since the virtual machine is just a QEMU emulation >> process on a
physical machine, and I worry that it is not using as >> much memory as a physical
machine. Understand this so that we can >> develop guidelines for optimal memory
usage scenarios for virtual >> machines.> > Thank you!> > >
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