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Re: 9 TiB vm memory creation
From: |
David Hildenbrand |
Subject: |
Re: 9 TiB vm memory creation |
Date: |
Tue, 15 Feb 2022 08:55:48 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 |
On 15.02.22 08:00, Ani Sinha wrote:
>
>
> On Mon, 14 Feb 2022, David Hildenbrand wrote:
>
>> On 14.02.22 13:36, Igor Mammedov wrote:
>>> On Mon, 14 Feb 2022 10:54:22 +0530 (IST)
>>> Ani Sinha <ani@anisinha.ca> wrote:
>>>
>>>> Hi Igor:
>>>>
>>>> I failed to spawn a 9 Tib VM. The max I could do was a 2 TiB vm on my
>>>> system with the following commandline before either the system
>>>> destabilized or the OOM killed killed qemu
>>>>
>>>> -m 2T,maxmem=9T,slots=1 \
>>>> -object
>>>> memory-backend-file,id=mem0,size=2T,mem-path=/data/temp/memfile,prealloc=off
>>>> \
>>>> -machine memory-backend=mem0 \
>>>> -chardev file,path=/tmp/debugcon2.txt,id=debugcon \
>>>> -device isa-debugcon,iobase=0x402,chardev=debugcon \
>>>>
>>>> I have attached the debugcon output from 2 TiB vm.
>>>> Is there any other commandline parameters or options I should try?
>>>>
>>>> thanks
>>>> ani
>>>
>>> $ truncate -s 9T 9tb_sparse_disk.img
>>> $ qemu-system-x86_64 -m 9T \
>>> -object
>>> memory-backend-file,id=mem0,size=9T,mem-path=9tb_sparse_disk.img,prealloc=off,share=on
>>> \
>>> -machine memory-backend=mem0
>>>
>>> works for me till GRUB menu, with sufficient guest kernel
>>> persuasion (i.e. CLI limit ram size to something reasonable) you can boot
>>> linux
>>> guest on it and inspect SMBIOS tables comfortably.
>>>
>>>
>>> With KVM enabled it bails out with:
>>> qemu-system-x86_64: kvm_set_user_memory_region:
>>> KVM_SET_USER_MEMORY_REGION failed, slot=1, start=0x100000000,
>>> size=0x8ff40000000: Invalid argument
>>>
>
> I have seen this in my system but not always. Maybe I should have dug
> deeper as to why i do see this all the time.
>
>>> all of that on a host with 32G of RAM/no swap.
>>>
>
> My system in 16 Gib of main memory, no swap.
>
>>
>> #define KVM_MEM_MAX_NR_PAGES ((1UL << 31) - 1)
>>
>> ~8 TiB (7,999999)
>
> That's not 8 Tib, thats 2 GiB. But yes, 0x8ff40000000 is certainly greater
> than 2 Gib * 4K (assuming 4K size pages).
"pages" don't carry the unit "GiB/TiB", so I was talking about the
actual size with 4k pages (your setup, I assume)
--
Thanks,
David / dhildenb
- Re: 9 TiB vm memory creation, Igor Mammedov, 2022/02/14
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/14
- Re: 9 TiB vm memory creation, Igor Mammedov, 2022/02/14
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation,
David Hildenbrand <=
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/15
- Re: 9 TiB vm memory creation, Ani Sinha, 2022/02/15
- Re: 9 TiB vm memory creation, David Hildenbrand, 2022/02/15
- Re: 9 TiB vm memory creation, Daniel P . Berrangé, 2022/02/15