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* [dpdk-dev] [Bug 383] dpdk virtio_user lack of notifications make vhost_net+napi stops tx buffers
@ 2020-01-09 15:47 bugzilla
  2020-01-09 15:55 ` eperezma
  2020-01-29 19:33 ` [dpdk-dev] [PATCH] vhost: flush shadow tx if there is no more packets Eugenio Pérez
  0 siblings, 2 replies; 12+ messages in thread
From: bugzilla @ 2020-01-09 15:47 UTC (permalink / raw)
  To: dev

https://bugs.dpdk.org/show_bug.cgi?id=383

            Bug ID: 383
           Summary: dpdk virtio_user lack of notifications make
                    vhost_net+napi stops tx buffers
           Product: DPDK
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: vhost/virtio
          Assignee: dev@dpdk.org
          Reporter: eupm90@gmail.com
  Target Milestone: ---

Using the current testpmd vhost_user as:

./app/testpmd -l 6,7,8 --vdev='net_vhost1,iface=/tmp/vhost-user1'
--vdev='net_vhost2,iface=/tmp/vhost-user2' -- -a -i --rxq=1 --txq=1 --txd=1024
--forward-mode=rxonly

And starting qemu using packed=on on the interface:

-netdev vhost-user,chardev=charnet1,id=hostnet1 -device
virtio-net-pci,rx_queue_size=256,...,packed=on

And start to tx in the guest using:

./dpdk/build/app/testpmd -l 1,2 --vdev=eth_af_packet0,iface=eth0 -- \
    --forward-mode=txonly --txq=1 --txd=256 --auto-start --txpkts 1500 \
    --stats-period 1

After first burst of packets (512 or a little more), sendto() will start to
return EBUSY. kernel NAPI is refusing to send more packets to virtio_net device
until it free old skbs.

However, virtio_net driver is unable to free old buffers since host
does not return them in `vhost_flush_dequeue_packed` until shadow queue is full
except for MAX_PKT_BURST (32) packets.

Sometimes we are lucky and reach this point, or packets are small enough to
fill the queue and flush, but if the packets and the virtqueue are big enough,
we will not be able to tx anymore.

-- 
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You are the assignee for the bug.

^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2020-02-05 15:46 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-09 15:47 [dpdk-dev] [Bug 383] dpdk virtio_user lack of notifications make vhost_net+napi stops tx buffers bugzilla
2020-01-09 15:55 ` eperezma
2020-01-15  7:05   ` Liu, Yong
2020-01-29 19:33 ` [dpdk-dev] [PATCH] vhost: flush shadow tx if there is no more packets Eugenio Pérez
2020-01-31 18:38   ` Kevin Traynor
2020-02-04  9:23     ` Eugenio Perez Martin
2020-02-04 13:48       ` Kevin Traynor
2020-02-04 15:05         ` Eugenio Perez Martin
2020-02-04 15:10           ` Maxime Coquelin
2020-02-05  9:09   ` Maxime Coquelin
2020-02-05  9:47   ` Maxime Coquelin
2020-02-05 15:45     ` Eugenio Perez Martin

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