This patch series resurrects the earlier multiple TX/RX queues
functionality for virtio_net, and addresses the issues pointed
out. It also includes an API to share irq's, f.e. amongst the
TX vqs.
I plan to run TCP/UDP STREAM and RR tests for local->host and
local->remote, and send the results in the next couple of days.
patch #1: Introduce VIRTIO_NET_F_MULTIQUEUE
patch #2: Move 'num_queues' to virtqueue
patch #3: virtio_net driver changes
patch #4: vhost_net changes
patch #5: Implement find_vqs_irq()
patch #6: Convert virtio_net driver to use find_vqs_irq()
Changes from rev2:
Michael:
-------
1. Added functions to handle setting RX/TX/CTRL vq's.
2. num_queue_pairs instead of numtxqs.
3. Experimental support for fewer irq's in find_vqs.
Rusty:
------
4. Cleaned up some existing "while (1)".
5. rvq/svq and rx_sg/tx_sg changed to vq and sg respectively.
6. Cleaned up some "#if 1" code.
Issue when using patch5:
-------------------------
The new API is designed to minimize code duplication. E.g.
vp_find_vqs() is implemented as:
static int vp_find_vqs(...)
{
return vp_find_vqs_irq(vdev, nvqs, vqs, callbacks, names, NULL);
}
In my testing, when multiple tx/rx is used with multiple netperf
sessions, all the device tx queues stops a few thousand times and
subsequently woken up by skb_xmit_done. But after some 40K-50K
iterations of stop/wake, some of the txq's stop and no wake
interrupt comes. (modprobe -r followed by modprobe solves this, so
it is not a system hang). At the time of the hang (#txqs=#rxqs=4):
# egrep "CPU|virtio0" /proc/interrupts | grep -v config
CPU0 CPU1 CPU2 CPU3
41: 49057 49262 48828 49421 PCI-MSI-edge virtio0-input.0
42: 5066 5213 5221 5109 PCI-MSI-edge virtio0-output.0
43: 43380 43770 43007 43148 PCI-MSI-edge virtio0-input.1
44: 41433 41727 42101 41175 PCI-MSI-edge virtio0-input.2
45: 38465 37629 38468 38768 PCI-MSI-edge virtio0-input.3
# tc -s qdisc show dev eth0
qdisc mq 0: root
Sent 393196939897 bytes 271191624 pkt (dropped 59897,
overlimits 0 requeues 67156) backlog 25375720b 1601p
requeues 67156
I am not sure if patch #5 is responsible for the hang. Also, without
patch #5/patch #6, I changed vp_find_vqs() to:
static int vp_find_vqs(...)
{
return vp_try_to_find_vqs(vdev, nvqs, vqs, callbacks, names,
false, false);
}
No packets were getting TX'd with this change when #txqs>1. This is
with the MQ-only patch that doesn't touch drivers/virtio/ directory.
Also, the MQ patch works reasonably well with 2 vectors - with
use_msix=1 and per_vq_vectors=0 in vp_find_vqs().
Patch against net-next - please review.
Signed-off-by: krkumar2@xxxxxxxxxx
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