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Date: Wed, 15 Jan 2014 12:03:53 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] Enabling vhost-net cause insane high memory usage.
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To: Piotr Karbowski <piotr.karbowski@gmail.com>
Cc: qemu-devel@nongnu.org

On Fri, Jan 10, 2014 at 12:00:31AM +0100, Piotr Karbowski wrote:
> Hello,
> 
> kernel 3.12.5, qemu-1.7.0.
> 
> With vhost=on, qemu shortly after start uses all its assigned memory
> (2G for example), without vhost-net enabled it does not go to more
> than 200 MB on my idling test virtual machine.

Could you explain how you measure that exactly?

> 100% reproducable. I
> think its not how it should be.
> 
> Full command:
> /usr/bin/qemu-system-x86_64 -machine accel=kvm -name _debian -usb
> -machine accel=kvm -cpu host,level=9 -smp cpus=2 -vga std -monitor unix://home/piotr/src/vmninja/sockets/_debian.monitor.socket,server,nowait
> -vnc unix://home/piotr/src/vmninja/sockets/_debian.vnc.socket -m
> 2048 -boot order=d,menu=on -drive
> if=ide,index=2,media=cdrom,id=virtcd -netdev
> tap,id=if0,helper=/usr/libexec/qemu-bridge-helper --br=lebridge0
> -device virtio-net-pci,netdev=if0,mac=de:ee:b3:9e:a3:d5,romfile=
> -drive
> file=/home/piotr/virt/kvm/_debian.raw,if=virtio,cache=writeback
> 
> -- Piotr.

Yes, this should not happen.
One interesting thing to try would be switching device type from
virtio-net to e1000.

This means vhost will be initialized but not started.

-- 
MST