Re: [Qemu-discuss] Guest network performance is painfully slow

[Tony Su]

 Unless someone says differently,
I believe that doesn't change the likely fact that the main KVM is
different than what you are doing and would perform much better.

Tony

On Sun, Aug 17, 2014 at 8:09 PM, JHM <address@hidden> wrote:
> Sorry, I'm taking my first steps with qemu here. The man page for kvm tells
> me
>
> The kvm wrapper script is used to provide compatibility with old qemu-kvm
> package which has been merged into qemu as of version 1.3.
>
> ... which is the the same as runnign qemu-system-x86_64 -enable-kvm.
>
>
> -- Julio H. Morimoto
> -- address@hidden
>
>
> On Sun, Aug 17, 2014 at 11:51 PM, Tony Su <address@hidden> wrote:
>>
>>  Is there some reason why you appear to be running "full virtualization"
>> qemu?
>> If you don't need special emulation features of regular QEMU, you
>> should instead be running the paravirtualized version (KVM) which will
>> provide vastly better performance.
>>
>> I haven't seen that "-enable-kvm" flag before, but it likely won't be
>> nearly the same as running KVM itself.
>>
>> Tony
>>
>> On Sun, Aug 17, 2014 at 7:34 PM, JHM <address@hidden> wrote:
>> > Salutations to all members, first off. This is my first post in the
>> > discussion group.
>> >
>> > I searched for this topic, but not much turned up from the archive here.
>> >
>> > Searching for "slow"
>> >
>> > http://lists.nongnu.org/archive/cgi-bin/namazu.cgi?query=slow&submit=Search!&idxname=qemu-discuss&max=100&result=normal&sort=score
>> >
>> > I would like to ask if anyone else had troubles with the network
>> > performance
>> > in the guest network. I am running qemu using ubuntu-14.04 as host. The
>> > guest is also ubuntu-14.04. In the guest OS, I have a LAMP stack
>> > properly
>> > configured. Users can reach the apache server inside via a host NATed
>> > tap
>> > interface. Anything poking the host at port 80 is passed into the
>> > private
>> > network between the guest/host. This all works well, and seems to be OK.
>> > Users can view websites and download files hosted in the guest LAMP.
>> >
>> > Except, users are getting very limited download speeds. While the host
>> > sits
>> > on a 100Mbps symmetric up/down link, users are only able to download at
>> > 15Kbps or max 30Kbps. I used to have the same setup running natively
>> > without
>> > QEMU and user download speeds were great. Once I moved the LAMP stack
>> > into
>> > the virtual machine, this issue came up. The following is the command
>> > line
>> > used to start up the qemu vm.
>> >
>> > qemu-system-x86_64 -hda disk1.qcow -m 1G -smp 4 -enable-kvm -netdev
>> > tap,id=tap0,ifname=tap0,script=tap-config.sh -device e1000,netdev=tap0
>> >
>> > Call me naive here, but is this kind of network performance expected?
>> > The
>> > guest OS is unusable.
>> >
>> > -- Julio H. Morimoto
>> > -- address@hidden
>
>