On 29/05/14 20:04, Eric Dumazet wrote: > 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> > > > Thank you, I will clarify the description. Jim -- 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
