Re: [Qemu-discuss] Qemu on Windows (with haxm and whpx), minimal Ubuntu, SLIRP and OpenVPN: very slow

[Michael Fritscher]

Am 13.05.2019 um 16:10:33 schrieb Michael Fritscher:
>   
> Am Montag, 13. Mai 2019 15:25 CEST, Michael Fritscher <address@hidden> schrieb:
>   
> > Am 13.05.2019 um 10:32:48 schrieb Michael Fritscher:
> > > Good day,
> > >
> > > Scenario:
> > > Host: Windows 7 and 10 64 bit, Skylake+ CPUs
> > > Qemu Version: 3.1 (4.0 isn't available yet on https://qemu.weilnetz.de/)
> > > Accelerators: HAXM and WHPX
> > > Guest: Ubuntu 18.04.2 64 bit, minimal install
> > > Guest's tasks: OpenVPN, iptables, tc
> > >
> > > Configuration:
> > > -machine q35,accel=kvm:hvf:whpx:hax:tcg
> > > -m 512
> > > -smp 1
> > > -rtc base=utc
> > > -drive file=layertc_environmentmanager_amsvm.iso,if=virtio,media=cdrom
> > > -vga std
> > > -netdev
> > >       user,id=natted,
> > >       restrict=n,
> > >       net=172.31.1.0/255.255.255.0,
> > >       dhcpstart=172.31.1.1,
> > >       host=172.31.1.3,
> > >       dns=172.31.1.4
> > > -device virtio-net,netdev=natted,mac=00:50:56:00:08:00
> > > -nodefaults
> > > -monitor tcp:localhost:4444
> > > -kernel vmlinuz
> > > -initrd initrd.img
> > > -append "boot=casper textonly quiet nosplash nofb fb=false pti=off spectre_v2=off 
> > > l1tf=off nospec_store_bypass_disable noprompt"
> > >
> > > (the iso is a casper livecd, but I start the linux kernel directly because of 
> > > boot speed)
> > >
> > > Problem:
> > > It is slow...
> > > While a openssl speed -elapsed -evp aes-128-cbc is ok (500MB/sec and beyond), 
> > > OpenVPN struggles.
> > > I get 70% virtual CPU usage , mostly on OpenVPN and system load while 
> > > transfering 1-2 MB/s with a UDP video stream. The measured delay is also
> > > rather spiky and is about 30...40 ms. On the host I get a cpu usage of about 
> > > 10% (=almost a core) I see this both on the server and the client
> > > side.
> > >
> > > On the player edition of the big commercial player, the results are _much_ 
> > > better (10% virtual CPU usage, delay of 4-6 ms)
> > >
> > > How can I further debug this? Do you know any knobs I can try? Slirp, while 
> > > there are warnings of being slow, doesn't seem to be the culprit as
> > > I can get easily >>10 MB/s through it. And I see the big CPU usage of OpenVPN
> > >
> > > Best regards,
> > > Michael Fritscher
> >
> > Hi again,
> >
> > after a bit of digging, openVPN seems to call read_hpet with about 1 kHz, which 
> > is, regarding to the program perf, the main culprit. Is a call
> > rate of this frequency normal and qemu is just very slow to handle them, or is 
> > there another problem?
> >
> > Best regards,
> > Michael Fritscher
> > --
> > ZfT - Zentrum für Telematik e.V.
> > Michael Fritscher
> > Magdalene-Schoch-Straße 5
> > 97074 Würzburg
> > Tel: +49 (931) 615 633 - 57
> > Fax: +49 (931) 615 633 - 11
> > Email: address@hidden
> > Web: http://www.telematik-zentrum.de
> >
> > Vorstand:
> > Prof. Dr. Klaus Schilling, Prof. Dr. Andreas Nüchter,  Hans-Joachim Leistner
> > Sitz: Gerbrunn
> > USt.-ID Nr.: DE 257 244 580, Steuer-Nr.:  257/111/70203
> > Amtsgericht Würzburg, Vereinsregister-Nr.: VR 200 167
>   
>   

For reference, on VWare Player I've even _no_ hpet_read. Seem I need to dig into OpenVPN further. Could be a bad time jitter or something the 
problem?

Best regards,
Michael Fritscher


--
ZfT - Zentrum für Telematik e.V.
Michael Fritscher
Magdalene-Schoch-Straße 5
97074 Würzburg
Tel: +49 (931) 615 633 - 57
Fax: +49 (931) 615 633 - 11
Email: address@hidden
Web: http://www.telematik-zentrum.de

Vorstand:
Prof. Dr. Klaus Schilling, Prof. Dr. Andreas Nüchter,  Hans-Joachim Leistner
Sitz: Gerbrunn
USt.-ID Nr.: DE 257 244 580, Steuer-Nr.:  257/111/70203
Amtsgericht Würzburg, Vereinsregister-Nr.: VR 200 167

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