On Thu, 2014-05-29 at 18:12 +0100, Jim Baxter wrote: > This fixes a problem with dropped packets over 16k CDC-NCM > when the connection is being heavily used. > > The issue was that the skb truesize for the unpacked NCM > packets was too high after they were cloned from the 16k > skb, this lead to the potential memory calculated by the > Kernel running out of memory earlier then it should. > > Signed-off-by: Jim Baxter <jim_baxter@xxxxxxxxxx> > --- Note the patch is OK, but changelog a bit misleading ;) Kernel was not running out of memory, because truesize was correct. The problem here is that a frame was consuming more kernel memory than really needed, so chances of hitting socket sk_rcvbuf limit was high. BTW : #define NTB_OUT_SIZE 16384 alloc_skb(size) -> kmalloc(16384 + sizeof(struct skb_shared_info)) -> roundup() => 32768 So truesize of the skb was infact ~32KB, which is really insane indeed. After your patch, its back to ~2KB Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx> -- 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
