[pve-devel] USB Host passthrough high cpu / interupt usage

[Stefan Priebe - Profihost AG]

Am 26.03.2014 10:49, schrieb Alexandre DERUMIER:
>>> At least i could hack QemuServer.pm and try it before doing any real patch. 
> 
> Yes!

mhm cpu load is lower (while doing nothing than getting serial data at
9600 baud) it is now 20% CPU Load instead of 30% before. But that's
still a lot for stupid serial stuff.

But latency is still very high now 120ms.

>>> Is it just replacing uhci with xhci all the time? 
> mmm,I'm not sure, because xhci don't support usb1 hub. (currently usb2 controller avec 1 usb1 controller plugged into it)
> 
> doc is here:
> http://git.qemu.org/?p=qemu.git;a=blob_plain;f=docs/usb2.txt;hb=HEAD
> 
> 
> maybe simply add a new controller:
>  -device nec-usb-xhci,id=xhci....
> 
> 
> then change bus=xhci.0 in usb devices

Yes did it that way.

> 
>>> Does the machine type (pc vs q35) makes any difference? 
> Don't known for usb. I known that q35 should improve pci express support in guest.

will try that too.

Do you know if i need to change the
/usr/share/qemu-server/pve-usb.cfg

file?

Stefan


> 
> ----- Mail original ----- 
> 
> De: "Stefan Priebe - Profihost AG" <s.priebe at profihost.ag> 
> À: "Alexandre DERUMIER" <aderumier at odiso.com> 
> Cc: pve-devel at pve.proxmox.com 
> Envoyé: Mercredi 26 Mars 2014 09:57:56 
> Objet: Re: [pve-devel] USB Host passthrough high cpu / interupt usage 
> 
> 
> Am 26.03.2014 08:47, schrieb Alexandre DERUMIER: 
>> Hi Stefan, 
>>
>> Do you see interrupts only when data transfer occur ? 
> 
> Not really sure how to check as data transfer occours all the time. 
> 
> 
>> I known that qemu usb3 implementation use less interrupts, 
>> maybe could we try to implemented it in proxmox. (xhci controller) 
>> (should not be a big task) 
> 
> At least i could hack QemuServer.pm and try it before doing any real patch. 
> 
> Is it just replacing uhci with xhci all the time? Does the machine type 
> (pc vs q35) makes any difference? 
> 
> Stefan 
> 
> 
>> ----- Mail original ----- 
>>
>> De: "Stefan Priebe" <s.priebe at profihost.ag> 
>> À: pve-devel at pve.proxmox.com 
>> Envoyé: Mardi 25 Mars 2014 23:07:48 
>> Objet: [pve-devel] USB Host passthrough high cpu / interupt usage 
>>
>> Hi, 
>>
>> i'm trying to pass through 5 usb devices from the host to the guest. 
>> What i'm wondering is the very high interupt and cpu usage of the guest. 
>>
>> These usb devices i'm passing are just tty / serial ones - so the data 
>> transfer is VERY low. 
>>
>> Does anybody habe an idea? Latency for USB data is also very high around 
>> 130ms. 
>>
>> Stefan 
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