[ovirt-users] Re: about the hugepage setting of the KVM server

Thank you for your reply! In fact, large page memory is mainly used for the SGA area of Oracle database. As you mentioned, large page memory is not used for other places except SGA. Therefore, WHEN allocating virtual machine memory, I will consider using fixed large page memory and ordinary memory to allocate. But it's worth revisiting my confusion: First, if I need to allocate large page memory to my virtual machine, do I need to specify large page memory on the physical machine it is located on first ? Otherwise, if the physical machine is not suitable, just assign large page memory to the virtual machine, is that ok? I see from your document, it is set to the physical machine first huge page memory, is through the kernel parameter way to set. Second, whether it is a physical machine or a virtual machine, once the large page memory is set, does it mean that the memory is divided into two areas, one is the normal 4K size area, the other is the large page memory area, for the application that uses them can only choose one of the two, can not mix, right? If so, I need to make a strict distinction between these applications, evaluate which use large page memory and which use plain memory, and plan for capacity to prevent overflow of memory requirements. From: Gianluca Cecchi <gianluca.cecchi(a)gmail.com&gt; Sent: Thursday, August 26, 2021 5:07 PM To: Tommy Sway <sz_cuitao(a)163.com>; users <users(a)ovirt.org&gt; Subject: Re: [ovirt-users] Re: about the hugepage setting of the KVM server On Thu, Aug 26, 2021 at 9:50 AM Tommy Sway <sz_cuitao(a)163.com <mailto:sz_cuitao@163.com> > wrote: Hi: I am running virtual machines on the KVM servers of oVirt env. The virtual machine is running database, which needs to set the memory huge page on the OPERATING system of the virtual machine. If I need to set the huge page on the VIRTUAL machine, do I also need to set huge page on the KVM physical machine? Or just on the virtual machine? What best practices do you recommend? Thank you very much! I think that this is still the reference for 4.4 https://mpolednik.github.io/2017/06/26/hugepages-and-ovirt/ The downside, if I'm correct, is that you will allocate as huge pages all the memory of the virtual machine and not only what potentially needed. Coming to your example of database VM: I want to allocate 32Gb as huge pages in a VM because that would be the memory assigned to the DB instance. But the VM for its work (user processes of the connections and other needs) will be configured as a 64Gb ram VM. In that case you "waste" 32Gb of huge pages allocation on the host, that you would prefer to be instead as normal pages.... Gianluca