On Wed, 2017-01-25 at 09:39 +0000, Hayes Wang wrote: > Oliver Neukum [mailto:oneukum@xxxxxxxx] > > 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: -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
