On Wed, 2017-01-25 at 09:39 +0000, Hayes Wang wrote:
> Oliver Neukum [mailto:[email protected]]
> > Sent: Wednesday, January 25, 2017 5:35 PM
> [...]
> > looking at r8152 I noticed that it uses NAPI. I never considered
> > this for the generic USB networking code as you cannot disable
> > interrupts for USB. Is it still worth it? What are the benefits?
>
> You could use napi_gro_receive() and it influences the performance.
You also could use napi_complete_done() instead of napi_complete(), as
it allows users to tune the performance vs latency for GRO.
Looking at this driver, I do not see any limitation on the number of
skbs that can be pushed into tp->rx_queue.
I wonder if this queue can end up consuming all memory of a host under
stress.
diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index
e1466b4d2b6c727148a884672bbd9593bf04b3ac..221df4a931b5c1073f1922d0fa0bbff158c73b7d
100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -1840,7 +1840,10 @@ static int rx_bottom(struct r8152 *tp, int budget)
stats->rx_packets++;
stats->rx_bytes += pkt_len;
} else {
- __skb_queue_tail(&tp->rx_queue, skb);
+ if (unlikely(skb_queue_len(&tp->rx_queue) >=
1000))
+ kfree_skb(skb);
+ else
+ __skb_queue_tail(&tp->rx_queue, skb);
}
find_next_rx:
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