[vfio-users] Brutal DPC Latency - how is yours? check it please and report back

[Eddie Yen]

I tested again with VM reboot, I found that this time is about 1000~1500μs.
Also I found that it easily get high while hard drive is loading, but only
few times.

Which specs you're using? Maybe it depends on CPU or patches.

2015-10-29 13:44 GMT+08:00 Blank Field <ihatethisfield at gmail.com>:

> If i understand it right, this software has a fixed latency error of 1
> ms(1000us) in windows 8-10 due to different kernel timer implementation. So
> i guess your latency is very good.
> On Oct 29, 2015 8:40 AM, "Eddie Yen" <missile0407 at gmail.com> wrote:
>
>> Thanks for information! And sorry I don'r read carefully at beginning
>> message.
>>
>> For my result, I got about 1000μs below and only few times got 1000μs
>> above when idling.
>>
>> I'm using 4820K and used 4 threads to VM, also  I set these 4 threads as
>> 4 cores in VM settings.
>> The OS is Windows 10.
>>
>> 2015-10-29 13:21 GMT+08:00 Blank Field <ihatethisfield at gmail.com>:
>>
>>> I think they're using this:
>>> www.thesycon.de/deu/latency_check.shtml
>>> On Oct 29, 2015 6:11 AM, "Eddie Yen" <missile0407 at gmail.com> wrote:
>>>
>>>> Sorry, but how to check DPC Latency?
>>>>
>>>> 2015-10-29 10:08 GMT+08:00 Nick Sukharev <nicksukharev at gmail.com>:
>>>>
>>>>> I just checked on W7 and I get 3000μs-4000μs one one of the guests
>>>>> when 3 guests are running.
>>>>>
>>>>> On Wed, Oct 28, 2015 at 4:52 AM, Sergey Vlasov <sergey at vlasov.me>
>>>>> wrote:
>>>>>
>>>>>> On 27 October 2015 at 18:38, LordZiru <lordziru at gmail.com> wrote:
>>>>>>
>>>>>>> I have brutal DPC Latency on qemu, no matter if using pci-assign or
>>>>>>> vfio-pci or without any passthrought,
>>>>>>>
>>>>>>> my DPC Latency is like:
>>>>>>> 10000,500,8000,6000,800,300,12000,9000,700,2000,9000
>>>>>>> and on native windows 7 is like:
>>>>>>> 20,30,20,50,20,30,20,20,30
>>>>>>>
>>>>>>
>>>>>> In Windows 10 guest I constantly have red bars around 3000μs
>>>>>> (microseconds), spiking sometimes up to 10000μs.
>>>>>>
>>>>>>
>>>>>>> I don't know how to fix it.
>>>>>>> this matter for me because i are using USB Sound Card for my VMs,
>>>>>>> and i get sound drop-outs every 0-4 secounds
>>>>>>>
>>>>>>>
>>>>>> That bugs me a lot too. I also use an external USB card and my DAW
>>>>>> periodically drops out :(
>>>>>>
>>>>>> I haven't tried CPU pinning yet though. And perhaps I should try
>>>>>> Windows 7.
>>>>>>
>>>>>>
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>>>>>>
>>>>>
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>>
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