Dnia Thursday 03 January 2008, Arnaldo Carvalho de Melo napisał: > Em Wed, Jan 02, 2008 at 11:34:25PM +0100, Tomasz Grobelny escreveu: > > with speed at which packets can be transmitted over the network. Is it > > the case for dccp as well? If so, does it mean that provided stable > > network conditions over longer period of time and using blocking version > > of sendmsg in a loop very few packets should be lost? (By very few I mean > > < 10%) > > If the application sends many packets in rapid succession before the > DCCP core gets permission from the CCID in use to send those packets to > the network what will happen is that sk_write_queue will have packets > waiting, using the memory allowed to be allocated for the socket send > buffer, which will make sock_alloc_send_skb wait for the packets in > sk_write_queue to be sent, freeing up send buffer space, when it will be > possible for sock_alloc_send_skb to actually allocate memory for the > packet and return to dccp_sendmsg, that in turn will return to the > application after putting the newly allocated packet in sk_write_queue, > doing the send buffer accounting and trying to send something in > dccp_write_xmit, where it will ask the CCID if it can send some more > packets, got it? > 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? 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? -- Regards, Tomasz Grobelny - 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
