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Re: x86_64 emulation on ppc64le POWER9 hardware - no multi threading
From: |
Kim-Norman Sahm |
Subject: |
Re: x86_64 emulation on ppc64le POWER9 hardware - no multi threading |
Date: |
Mon, 17 Aug 2020 08:29:01 +0000 |
User-agent: |
Microsoft-MacOutlook/16.39.20071300 |
Hi Cedric,
additional: which qemu and libvirt versions are you using?
Mit freundlichen Grüßen / Best regards,
Kim-Norman Sahm
Chief Technology Officer
Tel.: +49 151/46257663
Email: kim-norman.sahm@cloudical.io
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Am 06.08.20, 08:15 schrieb "Kim-Norman Sahm" <kim-norman.sahm@cloudical.io>:
Hi Cedric,
could you send me your complete xml file?
I get the error: process exited while connecting to monitor:
2020-08-03T17:43:50.146851Z qemu-system-x86_64: The -accel and "-machine
accel=" options are incompatible.
Best regards
KIm
Am 03.08.20, 19:37 schrieb "Cédric Le Goater" <clg@kaod.org>:
Again, with a correct answer,
On 8/3/20 3:47 PM, Kim-Norman Sahm wrote:
> hi,
>
>
>
> i’m running Debian 10 on POWER9 and would like to spawn x86_64
emulated VMs.
>
> The virtual machine is configured to run with 8 vpus but it’s very
slow.
>
> On the host you can see that the qemu-system-x86_64 process is using
just one core!
>
>
>
> Ppc64le guests are using multi cores, so its looks like an config
problem or software bug with the x86 emulator.
On a Power9 host (20.04), I did the following changes to an x86 domain :
<domain type='qemu'
xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
and at the end of the domain file :
<qemu:commandline>
<qemu:arg value='-accel'/>
<qemu:arg value='tcg,thread=multi'/>
</qemu:commandline>
The topology is defined as :
<cpu mode='custom' match='exact' check='none'>
<model fallback='forbid'>qemu64</model>
<topology sockets='1' cores='12' threads='2'/>
</cpu>
The VM is using MTTCG, as reported by top on the host :
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+
COMMAND
5761 libvirt+ 20 0 23.5g 1.8g 21888 R 2167 1.4 6:10.82
qemu-system-x86
In the guest :
$ lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
Address sizes: 40 bits physical, 48 bits virtual
CPU(s): 24
On-line CPU(s) list: 0-23
Thread(s) per core: 1
Core(s) per socket: 24
Socket(s): 1
NUMA node(s): 1
Vendor ID: AuthenticAMD
CPU family: 6
Model: 6
Model name: QEMU Virtual CPU version 2.1.0
Stepping: 3
CPU MHz: 511.035
BogoMIPS: 1022.07
Virtualization: AMD-V
L1d cache: 1.5 MiB
L1i cache: 1.5 MiB
L2 cache: 12 MiB
NUMA node0 CPU(s): 0-23
Vulnerability L1tf: Not affected
Vulnerability Mds: Not affected
Vulnerability Meltdown: Not affected
Vulnerability Spec store bypass: Vulnerable
Vulnerability Spectre v1: Mitigation; usercopy/swapgs barriers
and __user
pointer sanitization
Vulnerability Spectre v2: Mitigation; Full generic retpoline,
STIBP disab
led, RSB filling
Flags: fpu de pse tsc msr pae mce cx8 apic
sep mtrr pg
e mca cmov pat pse36 clflush mmx fxsr
sse sse2
ht syscall nx lm nopl cpuid pni cx16
popcnt hyp
ervisor lahf_lm cmp_legacy svm abm
sse4a 3dnowp
refetch vmmcall
Cheers,
C.