On Thu, 2014-05-22 at 20:07 +0100, Jim Baxter wrote: > > I have been investigating a network issue with bursts of network traffic > over USB CDC-NCM, the issue is that the kernel is dropping packets > because sk_rcvqueues_full() returns true due to skb2->truesize is always > 32960 instead of SKB_TRUESIZE(skb2->len) which is about 1800. > > The code I am trying to fix is this code below, it is splitting a set of > multiple network packets compressed into a single 16k packet into > individual skb's and sending them up the network stack. if skb are allocated with 16k = 16384 bytes, adding the struct skb_shared_info overhead and rounding up to power of two gives 32768 bytes. Chances to be able to allocate 32KB contiguous memory are slim after a while. I would set rx_max (rx_urb_size) to SKB_MAX_HEAD(0) so that you do not use high order allocations. What is the exact 'overhead' using ~4K instead of 16K exactly on this hardware ? -- 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
