On 4/12/07, David Miller <davem@xxxxxxxxxxxxx> wrote:
From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx> Date: Thu, 12 Apr 2007 18:14:54 -0300 > This patch replaces calls to do_gettimeofday at the receiver CCID 3 > with skb timestamps. The skb timestamps are computed earlier in the > receive path, experimental measurements have shown that up to several > hundred microseconds can lie between the skb receive timestamp and the > timestamp taken when CCID 3 receives the packet. This difference has > a negative impact on RTT estimation (reduced accuracy). > > Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx> > Acked-by: Ian McDonald <ian.mcdonald@xxxxxxxxxxx> > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx> And this creates an even deeper dependency on the global packet timestamping facility. Those are supposed to be enabled only in obscure circumstances because timestamping every packet is incredibly expensive. Please find a better way.
Well, there seems to be just one better way, to timestamp the packet as soon as it enters the dccp stack, in dccp_v[46]_rcv, and consider the time from the driver -> ip v[46] -> dccp_v[46]_ as "in the wire". - 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
