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

Quentin Deldycke quentindeldycke at gmail.com
Tue Jan 12 07:34:01 UTC 2016 

For my part, most game are more than playable...
Battlefront is flawless, Fallout 4 too. I nearly never find laggy games.

For my part, i use my gpu as a sound card and i have totally no glitches.

Main problem for me is heroes of the storm (playing with friends,
brother...),
which is completely catastrophic. My fps are playing yoyo between 200 and
15 -_-'


But yes. Motherboards are buggy as f***. For my parts, once by month,
the dropbox of "gpu default output" on bios to select igpu or pcie card
seems
to be totally useless. pcie is used in any cases. I need to cmos
motherboard.

Also, usb is hardly buggy sometimes... When i boot the pc, it doesn't work
and detect
a buggy device on one of my root ports. Which delay boot for ~1 minute. But
after this,
all ports are working...

--
Deldycke Quentin


On 11 January 2016 at 23:44, Frank Wilson <frank at zenlambda.com> wrote:

> Not sure if this is adding much to the conversation but I gave up on
> my GPU passthrough project because of horrible DPC latency. Didn't
> affect the graphics so much but sound was terrible.
>
> My gut feeling was the hardware wasn't good enough. I was using an AMD
> 8 core piledriver cpu with an Asus crosshair 5 motherboard. The
> motherboard has broken IVRS tables so it's not supported by Xen.
>
> I've been looking with great interest at Intel skylake. I'm also
> interested in technologies like xen-gt. However I just don't trust
> motherboard manufacturers to deliver firmware without critical bugs
> that knock out virtualisation features that I need.
>
> A lot of the GPU passthrough demos are very impressive but often don't
> demonstrate dropout-free audio.
>
>
> Frank
>
> On 11 January 2016 at 08:59, rndbit <rndbit at sysret.net> wrote:
> > Tried Milos' config too - DPC latency got worse. I use AMD cpu though so
> its
> > hardly comparable.
> > One thing to note is that both VM and bare metal (same OS) score around
> 5k
> > points in 3dmark fire strike test (VM 300 points less). Sounds not too
> bad
> > but in reality bf4 is pretty much unplayable in VM due to bad performance
> > and sound glitches while playing it on bare metal is just fine. Again DPC
> > latency on bare metal even under load is ok - occasional spike here and
> > there but mostly its within norm. Any kind of load on VM makes DPC go
> nuts
> > and performance is terrible. I even tried isolcpus=4,5,6,7 and binding
> vm to
> > those free cores - its all the same.
> >
> > Interesting observation is that i used to play titanfall without a hitch
> in
> > VM some time in the past, 3.10 kernel or so (no patches). When i get free
> > moment ill try downgrading kernel, maybe problem is there.
> >
> >
> > On 2016.01.11 10:39, Quentin Deldycke wrote:
> >
> > Also, i juste saw something:
> >
> > You use ultra (4k?) settings on a 770gtx. This is too heavy for it. You
> have
> > less than 10fps. So in fact if you loose let's say 10% of performance,
> you
> > will barely see it.
> >
> > What we search is a very high reponse time. Could you please compare your
> > system with a less heavy benchmark. It is easier to see the difference at
> > ~50-70 fps.
> >
> > In my case, this configuration work. But my fps fluctuate quite a lot. If
> > you are a bit a serious gamer, this falls are not an option during game
> :)
> >
> > --
> > Deldycke Quentin
> >
> >
> > On 11 January 2016 at 08:54, Quentin Deldycke <quentindeldycke at gmail.com
> >
> > wrote:
> >>
> >> Using this mode,
> >>
> >> DPC Latency is hugely buggy using this mode.
> >>
> >> My fps are also moving on an apocaliptic way: from 80 to 45 fps without
> >> moving on ungine valley.
> >>
> >> Do you have anything working on your linux? (i have plasma doing nothing
> >> on another screen)
> >>
> >> Ungine heaven went back to 2600 points from 3100
> >> Cinebench r15: single core 124
> >>
> >>
> >> Could you please send your whole xml file, qemu version and kernel
> config
> >> / boot?
> >>
> >> I will try to get 3dmark and verify host / virtual comparison
> >>
> >> --
> >> Deldycke Quentin
> >>
> >>
> >> On 9 January 2016 at 20:24, Milos Kaurin <milos.kaurin at gmail.com>
> wrote:
> >>>
> >>> My details:
> >>> Intel(R) Core(TM) i7-4770 CPU @ 3.40GHz
> >>> 32GB total ram
> >>> hugetables at 16x1GB for the guest (didn't have much to do with 3dmark
> >>> results)
> >>>
> >>> I have had the best performance with:
> >>>
> >>>   <vcpu placement='static'>8</vcpu>
> >>>   <cpu mode='custom' match='exact'>
> >>>     <model fallback='allow'>host-passthrough</model>
> >>>     <topology sockets='1' cores='4' threads='2'/>
> >>>   </cpu>
> >>>
> >>> No CPU pinning on either guest or host
> >>>
> >>> Benchmark example (Bare metal Win10 vs Fedora Guest Win10)
> >>> http://www.3dmark.com/compare/fs/7076732/fs/7076627#
> >>>
> >>>
> >>> Could you try my settings and report back?
> >>>
> >>> On Sat, Jan 9, 2016 at 3:14 PM, Quentin Deldycke
> >>> <quentindeldycke at gmail.com> wrote:
> >>> > I use virsh:
> >>> >
> >>> > ===SNIP===
> >>> >   <vcpu placement='static'>3</vcpu>
> >>> >   <cputune>
> >>> >     <vcpupin vcpu='0' cpuset='1'/>
> >>> >     <vcpupin vcpu='1' cpuset='2'/>
> >>> >     <vcpupin vcpu='2' cpuset='3'/>
> >>> >     <emulatorpin cpuset='6-7'/>
> >>> >   </cputune>
> >>> > ===SNAP===
> >>> >
> >>> > I have a prepare script running:
> >>> >
> >>> > ===SNIP===
> >>> > sudo mkdir /cpuset
> >>> > sudo mount -t cpuset none /cpuset/
> >>> > cd /cpuset
> >>> > echo 0 | sudo tee -a cpuset.cpu_exclusive
> >>> > echo 0 | sudo tee -a cpuset.mem_exclusive
> >>> >
> >>> > sudo mkdir sys
> >>> > echo 'Building shield for core system... threads 0 and 4, and we
> place
> >>> > all
> >>> > runnning tasks there'
> >>> > /bin/echo 0,4 | sudo tee -a sys/cpuset.cpus
> >>> > /bin/echo 0 | sudo tee -a sys/cpuset.mems
> >>> > /bin/echo 0 | sudo tee -a sys/cpuset.cpu_exclusive
> >>> > /bin/echo 0 | sudo tee -a sys/cpuset.mem_exclusive
> >>> > for T in `cat tasks`; do sudo bash -c "/bin/echo $T >
> >>> > sys/tasks">/dev/null
> >>> > 2>&1 ; done
> >>> > cd -
> >>> > ===SNAP===
> >>> >
> >>> > Note that i use this command line for the kernel
> >>> > nohz_full=1,2,3,4,5,6,7 rcu_nocbs=1,2,3,4,5,6,7 default_hugepagesz=1G
> >>> > hugepagesz=1G hugepages=12
> >>> >
> >>> >
> >>> > --
> >>> > Deldycke Quentin
> >>> >
> >>> >
> >>> > On 9 January 2016 at 15:40, rndbit <rndbit at sysret.net> wrote:
> >>> >>
> >>> >> Mind posting actual commands how you achieved this?
> >>> >>
> >>> >> All im doing now is this:
> >>> >>
> >>> >> cset set -c 0-3 system
> >>> >> cset proc -m -f root -t system -k
> >>> >>
> >>> >>   <vcpu placement='static'>4</vcpu>
> >>> >>   <cputune>
> >>> >>     <vcpupin vcpu='0' cpuset='4'/>
> >>> >>     <vcpupin vcpu='1' cpuset='5'/>
> >>> >>     <vcpupin vcpu='2' cpuset='6'/>
> >>> >>     <vcpupin vcpu='3' cpuset='7'/>
> >>> >>     <emulatorpin cpuset='0-3'/>
> >>> >>   </cputune>
> >>> >>
> >>> >> Basically this puts most of threads to 0-3 cores including emulator
> >>> >> threads. Some threads cant be moved though so they remain on 4-7
> >>> >> cores. VM
> >>> >> is given 4-7 cores. It works better but there is still much to be
> >>> >> desired.
> >>> >>
> >>> >>
> >>> >>
> >>> >> On 2016.01.09 15:59, Quentin Deldycke wrote:
> >>> >>
> >>> >> Hello,
> >>> >>
> >>> >> Using cpuset, i was using the vm with:
> >>> >>
> >>> >> Core 0: threads 0 & 4: linux + emulator pin
> >>> >> Core 1,2,3: threads 1,2,3,5,6,7: windows
> >>> >>
> >>> >> I tested with:
> >>> >> Core 0: threads 0 & 4: linux
> >>> >> Core 1,2,3: threads 1,2,3: windows
> >>> >> Core 1,2,3: threads 5,6,7: emulator
> >>> >>
> >>> >> The difference between both is huge (DPC latency is mush more
> stable):
> >>> >> Performance on single core went up to 50% (cinebench ratio by core
> >>> >> from
> >>> >> 100 to 150 points)
> >>> >> Performance on gpu went up to 20% (cinebench from 80fps to 100+)
> >>> >> Performance on "heroes of the storm" went from 20~30 fps to stable
> 60
> >>> >> (and
> >>> >> much time more than 100)
> >>> >>
> >>> >> (performance of Unigine Heaven went from 2700 points to 3100 points)
> >>> >>
> >>> >> The only sad thing is that i have the 3 idle threads which are
> barely
> >>> >> used... Is there any way to put them back to windows?
> >>> >>
> >>> >> --
> >>> >> Deldycke Quentin
> >>> >>
> >>> >>
> >>> >> On 29 December 2015 at 17:38, Michael Bauer <michael at m-bauer.org>
> >>> >> wrote:
> >>> >>>
> >>> >>> I noticed that attaching a DVD-Drive from the host leads to HUGE
> >>> >>> delays.
> >>> >>> I had attached my /dev/sr0 to the guest and even without a DVD in
> the
> >>> >>> drive
> >>> >>> this was causing huge lag about once per second.
> >>> >>>
> >>> >>> Best regards
> >>> >>> Michael
> >>> >>>
> >>> >>>
> >>> >>> Am 28.12.2015 um 19:30 schrieb rndbit:
> >>> >>>
> >>> >>> 4000μs-16000μs here, its terrible.
> >>> >>> Tried whats said on
> >>> >>> https://lime-technology.com/forum/index.php?topic=43126.15
> >>> >>> Its a bit better with this:
> >>> >>>
> >>> >>>   <vcpu placement='static'>4</vcpu>
> >>> >>>   <cputune>
> >>> >>>     <vcpupin vcpu='0' cpuset='4'/>
> >>> >>>     <vcpupin vcpu='1' cpuset='5'/>
> >>> >>>     <vcpupin vcpu='2' cpuset='6'/>
> >>> >>>     <vcpupin vcpu='3' cpuset='7'/>
> >>> >>>     <emulatorpin cpuset='0-3'/>
> >>> >>>   </cputune>
> >>> >>>
> >>> >>> I tried isolcpus but it did not yield visible benefits. ndis.sys is
> >>> >>> big
> >>> >>> offender here but i dont really understand why. Removing network
> >>> >>> interface
> >>> >>> from VM makes usbport.sys take over as biggest offender. All this
> >>> >>> happens
> >>> >>> with performance governor of all cpu cores:
> >>> >>>
> >>> >>> echo performance | tee
> >>> >>> /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor >/dev/null
> >>> >>>
> >>> >>> Cores remain clocked at 4k mhz. I dont know what else i could try.
> >>> >>> Does
> >>> >>> anyone have any ideas..?
> >>> >>>
> >>> >>> On 2015.10.29 08:03, Eddie Yen wrote:
> >>> >>>
> >>> >>> 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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