[pve-devel] [PATCH qemu-server 0/2] hv_stimer && hv_synic support

[Alexandre DERUMIER]

>>is there any more documentation for those flags and why exactly they are 
>>needed (the redhat bugzilla entry is rather sparse with information) 

but some notes in kernel patch

https://patchwork.kernel.org/patch/7727711/
"Per Hyper-V specification (and as required by Hyper-V-aware guests),
SynIC provides 4 per-vCPU timers.  Each timer is programmed via a pair
of MSRs, and signals expiration by delivering a special format message
to the configured SynIC message slot and triggering the corresponding
synthetic interrupt.
"

microsoft specification about hyperv (they are reference of synic)

https://docs.microsoft.com/en-us/virtualization/hyper-v-on-windows/reference/tlfs

>>also why only with qemu 2.12 ? does it not work for the current 2.11? 
>>(or did you do this so that the live migration works?) 

don't want to break live migration indeed.
Maybe could we introduce an extra minor version in qemu binary for this kind of change ?  qemu 2.11.1.X  ?


>>does this also work with older win10/2016? 

I'm sure it's working for windows >=8  (win8,win2012,win8.1,win2012r2,win10,win2016)

the microsoft docs seem to have reference to synic in 2008r2/7  (don't known about 2008/vista)


----- Mail original -----
De: "Dominik Csapak" <d.csapak at proxmox.com>
À: "pve-devel" <pve-devel at pve.proxmox.com>
Envoyé: Mardi 26 Juin 2018 10:28:55
Objet: Re: [pve-devel] [PATCH qemu-server 0/2] hv_stimer && hv_synic support

On 06/24/2018 08:47 PM, Alexandre Derumier wrote: 
> Users have reported cpu problem with last windows 10 update (1803) 
> https://forum.proxmox.com/threads/high-cpu-load-for-windows-10-guests-when-idle.44531/ 
> 
> adding hyperv hv_stimer && hv_synic fix the problem. 
> 
> This patch series add support to defines them as cpu options, 
> 
> and enable them by default for next qemu 2.12 && win >= 8. (don't have tested win7) 
> 
> Alexandre Derumier (2): 
> add hv_stimer, hv_synic cpu flags option 
> enable hv_synic && hv_stimer by default for qemu 2.12 && windows >= 8 
> 
> PVE/QemuServer.pm | 9 +++++++-- 
> 1 file changed, 7 insertions(+), 2 deletions(-) 
> 

hi, 

great to see that there is a nice fix for that. 

is there any more documentation for those flags and why exactly they are 
needed (the redhat bugzilla entry is rather sparse with information) 

also why only with qemu 2.12 ? does it not work for the current 2.11? 
(or did you do this so that the live migration works?) 

does this also work with older win10/2016? 

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