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From: "Wiles, Keith" <keith.wiles@intel.com>
To: "Avi Cohen (A)" <avi.cohen@huawei.com>
CC: "users@dpdk.org" <users@dpdk.org>
Thread-Topic: [dpdk-users] OVS vs OVS-DPDK
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Date: Wed, 24 May 2017 13:23:22 +0000
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Subject: Re: [dpdk-users] OVS vs OVS-DPDK
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> On May 24, 2017, at 3:29 AM, Avi Cohen (A) <avi.cohen@huawei.com> wrote:
>=20
> Hello
> Let me  ask it in a different way:
> I want to understand the reasons for the  differences in performance betw=
een OVS-DPDK and standard OVS My setup is:  ovs/ovs-dpdk is running @ host =
communicating with a VM
>=20
> OVS-DPDK
> 1. packet is received via physical port to the device.=20
>=20
> 2.DMA  transfer   to mempools on huge-pages  allocated by dpdk-ovs - in  =
user-space.
>=20
> 3. OVS-DPDK  copies this packet to the shared-vring of the associated  gu=
est (shared between ovs-dpdk userspace process and guest)=20
>=20
> 4. guest OS copies the packet to  userspace application on VM .
>=20
> Standard OVS
>=20
> 1. packet is received via physical port to the device.=20
>=20
> 2.packet is processed by the OVS and transferred to a virtio device conne=
cted to the VM - whar are the additional overhead here ?  QEMU processing  =
- translation , VM exit ??  other ?
>=20
> 3. guest OS copies the packet to  userspace application on VM .
>=20
>=20
> Question:  what are the additional overhead in the standard OVS   that ca=
use to poor performance related to the OVS-DPDK setup ?
> I'm not talking about  the PMD improvements (OVS-DPDK)  running on the ho=
st - but on overhead in the VM context in the standard OVS setup

The primary reasons are OVS is not using DPDK and OVS is using the Linux ke=
rnel as well :-)

>=20
> Best Regards
> avi

Regards,
Keith