On Mon, Jul 03 2023, "Michael S. Tsirkin" <m...@redhat.com> wrote:
> On Mon, Jul 03, 2023 at 11:27:11PM +0800, Heng Qi wrote: >> 1. Currently, a received encapsulated packet has an outer and an inner >> header, but >> the virtio device is unable to calculate the hash for the inner header. The >> same >> flow can traverse through different tunnels, resulting in the encapsulated >> packets being spread across multiple receive queues (refer to the figure >> below). >> However, in certain scenarios, we may need to direct these encapsulated >> packets of >> the same flow to a single receive queue. This facilitates the processing >> of the flow by the same CPU to improve performance (warm caches, less >> locking, etc.). >> >> client1 client2 >> | +-------+ | >> +------->|tunnels|<--------+ >> +-------+ >> | | >> v v >> +-----------------+ >> | monitoring host | >> +-----------------+ >> >> To achieve this, the device can calculate a symmetric hash based on the >> inner headers >> of the same flow. >> >> 2. For legacy systems, they may lack entropy fields which modern protocols >> have in >> the outer header, resulting in multiple flows with the same outer header but >> different inner headers being directed to the same receive queue. This >> results in >> poor receive performance. >> >> To address this limitation, inner header hash can be used to enable the >> device to advertise >> the capability to calculate the hash for the inner packet, regaining better >> receive performance. >> >> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/173 >> Signed-off-by: Heng Qi <hen...@linux.alibaba.com> >> Reviewed-by: Xuan Zhuo <xuanz...@linux.alibaba.com> >> Reviewed-by: Parav Pandit <pa...@nvidia.com> > > Cornelia last minute comments before I start a vote? Please just go ahead. --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org
