Em Fri, Jan 04, 2008 at 11:25:29AM +1300, Ian McDonald escreveu: > On Jan 4, 2008 11:19 AM, Tomasz Grobelny <tomasz@xxxxxxxxxxxxxxxxxxxxxxx> wrote: > > I think I almost got it. Thanks a lot for the detailed explanation. But I've > > got two more questions: > > 1. How can I control the amount of "memory allowed to be allocated for the > > socket send buffer"? It it somehow connected with tx_qlen or is it not? > > I wrote the code here so let me comment - there is no fixed amount of > memory allocated - it is determined by the tx_qlen. I was looking at there is no memory allocated in advance nor explicit, DCCP specific mechanism for limiting the amount of memory a socket can use for its write queue, but DCCP uses sock_alloc_send_skb and that function does memory accounting and checks if the maximum memory (SO_SNDBUF) has been reached, when it makes the app to sleep if O_NONBLOCK is not set. > implementing memory limits but it got too hard and as DCCP doesn't > combine packets I thought it made it much simpler just to put a limit > by packets. > > > 2. If I decide that for whatever reason a given skb already in sk_write_queue > > should not be transmitted I should remove it from queue and call kfree_skb on > > it, it that right? > > Correct. Remember of course all your locking mechanisms. If you want a > good example look at the below towards the end: > http://wand.net.nz/~iam4/dccp/patches20/30-best_packet_next.diff > > (NB this patch applies against 2.6.20 after previous patches in series). Correct if he is in-kernel. - Arnaldo - To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
