<div dir="ltr">I finally got my server to a state that I can start doing some performance testing. While researching the best way to handle network adapters, I came across the following.<div> </div><div>I'm currently using the following settings to utilize a bridge on my machine named br0</div><div>-net bridge,br=br0 -net nic,macaddr=52:54:00:81:08:AB,model=virtio </div><div> </div><div>Doing some more reading, it looks like this might actually have better performance</div><div>-netdev bridge,br=br0,id=vnet0 -device virtio-net-pci,netdev=vnet0,mac=52:54:00:81:08:AB,id=nic1 </div><div> </div><div>The 2nd command works, however passwing the mac address does not. It always defaults to the generic mac. Am I doing something wrong? If I try to use macaddr as the parameter I can an error that it isn't valid. Does anyone know if there is even a functional difference between these two?</div><div> </div><div>Lastly, my system has 4 NIC cards. Would it be faster or more efficient to pass through the nic itself? From what I read, it the 2nd option above should be just as fast as a physical NIC.</div></div> <div class="gmail_quote"><div dir="ltr">On Fri, Oct 30, 2015 at 9:05 PM Dan Ziemba <<a href="mailto:zman0900@gmail.com">zman0900@gmail.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I'm using a 7850 for the host and a R9 280x (same as 7970) for the VM. i7 3770 cpu. I used to use the 7850 for the VM before I got the 280x, but I think that might have been only back when I was using Xen. Setup works great for me, except for the ACS issues requiring the patch. -----Original Message----- From: Ryan Flagler <<a href="mailto:ryan.flagler@gmail.com" target="_blank">ryan.flagler@gmail.com</a>> To: Dan Ziemba <<a href="mailto:zman0900@gmail.com" target="_blank">zman0900@gmail.com</a>>, Mark Weiman <<a href="mailto:mark.weiman@markzz.co" target="_blank">mark.weiman@markzz.co</a> m>, <a href="mailto:vfio-users@redhat.com" target="_blank">vfio-users@redhat.com</a> Subject: Re: [vfio-users] KVM options and the effect on performance Date: Fri, 30 Oct 2015 14:13:00 +0000 Thanks for the config examples. What GPU's do you guys use? I'm struggling with 2 different AMD Radeon models (7850 and R9 380). Early on in my research I noticed people saying Radeons were easier to get working, but the deeper I dig, it seems nVidia cards have some initial quirks, but are more stable. Hopefully next week I'll get some time to tweak my setup more. On Thu, Oct 29, 2015 at 11:15 PM Dan Ziemba <<a href="mailto:zman0900@gmail.com" target="_blank">zman0900@gmail.com</a>> wrote: > I'll also throw in the scripting I used to use before switching to > libvirt a month or so back. The latest version is with the default > i440 machine, but if you look back in the history some you can see > how > I was using q35 before. > > <a href="https://github.com/zman0900/qemu-vifo" rel="noreferrer" target="_blank">https://github.com/zman0900/qemu-vifo</a> > > -----Original Message----- > From: Mark Weiman <<a href="mailto:mark.weiman@markzz.com" target="_blank">mark.weiman@markzz.com</a>> > To: Ryan Flagler <<a href="mailto:ryan.flagler@gmail.com" target="_blank">ryan.flagler@gmail.com</a>>, <a href="mailto:vfio-users@redhat.com" target="_blank">vfio-users@redhat.com</a> > Subject: Re: [vfio-users] KVM options and the effect on performance > Date: Fri, 30 Oct 2015 00:00:21 -0400 > > To be honest, I have found little to no real noticeable difference > between many of them. My VMs usually use a qcow2 image that are > mounted via virtio. > > As for a CPU, I use an i7-4970K and it works beautifully. It really > boils down to when you choose your hardware whether or not you've > done > the research beforehand so you can have a good time rather than > fighting it. If I were to build my main rig again, I would have > looked > closer into the motherboard so I wouldn't have to patch my kernel, > although it really is not a problem to do with that CPU (I also > provide > a slightly modified version of Dan Ziemba's PKGBUILD [1] that > includes > the i915 and acs patch from my Arch Linux repository [2]). > > As for your Wiki idea, since this all is open source software, there > is > nothing preventing you from contributing to documentation on > this. The > Arch Linux Wiki does provide a lot of information on how to do all of > this [3] and can guide you even if you aren't using Arch Linux. Just > change the Arch specific bits to whatever distribution you use. > > If it helps, this is the script I use when I run my Windows 10 VM > [4]. It's really sloppy, but it seems to work for me. > > As for using btrfs to store images, I use it to store my images and I > have had no issue. It just has to be pointed out that btrfs is still > under development, so you should just put that under consideration. > > Didn't want to leave ya hangin, > Mark Weiman > > [1] <a href="https://aur.archlinux.org/packages/linux-vfio-lts" rel="noreferrer" target="_blank">https://aur.archlinux.org/packages/linux-vfio-lts</a> > [2] <a href="https://wiki.archlinux.org/index.php/Unofficial_user_repositories" rel="noreferrer" target="_blank">https://wiki.archlinux.org/index.php/Unofficial_user_repositories</a> > #m > arkzz > [3] <a href="https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVMF" rel="noreferrer" target="_blank">https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVMF</a> > [4] <a href="http://info.markzz.com/kvm-start.sh" rel="noreferrer" target="_blank">http://info.markzz.com/kvm-start.sh</a> > > On Thu, 2015-10-29 at 16:50 +0000, Ryan Flagler wrote: > > Hey everyone, sorry if I'm doing this wrong, this is my first time > > using a mailing list. (Side note, if anyone has a better way to > view > > historical emails than the web page, please let me know) > > > > I've been tinkering with KVM for a bit on my system and had some > > general performance questions to ask. I see a lot of people doing > VGA > > passthrough using the q35 chipset instead of the i440FX chipset. > I've > > personally had no luck getting q35 to be stable for me, and I've > seen > > some people say it's not worth the headache. But the big question > to > > me, is there a performance difference with CPU, VGA, memory etc. > > using q35? I'm not looking for specifics, but I'm curious about the > > following qemu parameters. > > > > Which chipset emulation performs better and in what areas? > > q35 vs i440fx > > > > What is the best way to pass a disk through to a VM to get the most > > performance? > > .img file, /dev/sd[x] disk, virtio-scsi, etc. > > > > What is the best way to handle networking? > > virtio-nic, hardware passthrough, bridge, nat, etc. > > > > What is the best way to assign CPUs? > > cpu pinning, assigning host cpu parameters, etc. > > > > Does the BIOS have an effect on performance? > > seabios vs OVMF? > > > > CPU/Chipset IOMMU support - Not necessarily performance related, > but > > stability? > > e5 vs e3 vs i7 vs cpu architecture etc. What things are good to > look > > for, what are bad? Etc. > > > > What would be interesting, especially as a new KVM/Qemu user, would > > be to see an entire wiki/performance page with examples and > > specifics. It's hard to filter through all the various pages of VM > > options where people don't really explain why they're doing > something > > the way they are. > > > > Examples: > > > > Disk Options > > Best > > -device virtio-scsi-pci,id=scsi > > -drive file=/dev/sd[x],id=disk,format=ls raw,if=none -device scsi- > > hd,drive=disk > > > > Better > > -device virtio-scsi-pci,id=scsi > > -drive file=/opt/[vm_name].img,id=disk,format=raw -device scsi- > > hd,drive=disk > > > > Good > > -drive file=/opt/[vm_name].img,id=disk,format=raw -device ide- > > hd,bus=ide.0,drive=disk > > > > And maybe an overall explanation of why one is better over the > other. > > I know this may not exist and I'm not asking a single person to do > > the leg work, but being new to this, it's hard to focus on the > pieces > > that matter vs just using the first thing I find that works. If > there > > is a "right" place to start something like this I'd be happy to > setup > > a generic page where more experienced people could easily > contribute. > > > > Thanks - Ryan > > > > > > _______________________________________________ > > vfio-users mailing list > > <a href="mailto:vfio-users@redhat.com" target="_blank">vfio-users@redhat.com</a> > _______________________________________________ > vfio-users mailing list > <a href="mailto:vfio-users@redhat.com" target="_blank">vfio-users@redhat.com</a> > <a href="https://www.redhat.com/mailman/listinfo/vfio-users" rel="noreferrer" target="_blank">https://www.redhat.com/mailman/listinfo/vfio-users</a> </blockquote></div>