On 2017年03月03日 22:39, Willem de Bruijn wrote:
From: Willem de Bruijn <will...@google.com>
Convert virtio-net to a standard napi tx completion path. This enables
better TCP pacing using TCP small queues and increases single stream
throughput.
The virtio-net driver currently cleans tx descriptors on transmission
of new packets in ndo_start_xmit. Latency depends on new traffic, so
is unbounded. To avoid deadlock when a socket reaches its snd limit,
packets are orphaned on tranmission. This breaks socket backpressure,
including TSQ.
Napi increases the number of interrupts generated compared to the
current model, which keeps interrupts disabled as long as the ring
has enough free descriptors. Keep tx napi optional for now. Follow-on
patches will reduce the interrupt cost.
Signed-off-by: Willem de Bruijn <will...@google.com>
---
drivers/net/virtio_net.c | 73 ++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 61 insertions(+), 12 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8c21e9a4adc7..9a9031640179 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -33,6 +33,8 @@
static int napi_weight = NAPI_POLL_WEIGHT;
module_param(napi_weight, int, 0444);
+static int napi_tx_weight = NAPI_POLL_WEIGHT;
+
Maybe we should use module_param for this? Or in the future, use
tx-frames-irq for a per-device configuration.
Thanks
