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  • ? jiang's avatar
    virtio-net: lower min ring num_free for efficiency · 718be6ba
    ? jiang authored
    This change lowers ring buffer reclaim threshold from 1/2*queue to budget
    for better performance. According to our test with qemu + dpdk, packet
    dropping happens when the guest is not able to provide free buffer in
    avail ring timely with default 1/2*queue. The value in the patch has been
    tested and does show better performance.
    Test setup: iperf3 to generate packets to guest (total 30mins, pps 400k, UDP)
    avg packets drop before: 2842
    avg packets drop after: 360(-87.3%)
    Further, current code suffers from a starvation problem: the amount of
    work done by try_fill_recv is not bounded by the budget parameter, thus
    (with large queues) once in a while userspace gets blocked for a long
    time while queue is being refilled. Trigger refills earlier to make sure
    the amount of work to do is limited.
    Signed-off-by: default avatarjiangkidd <>
    Acked-by: default avatarJason Wang <>
    Acked-by: default avatarMichael S. Tsirkin <>
    Signed-off-by: default avatarMichael S. Tsirkin <>