On 10/31/06, Stephen Hemminger <[EMAIL PROTECTED]> wrote:
I reran the tests, this time using my DSL line to home (80ms 1Mbit/sec). http://developer.osdl.org/shemminger/tcp/2.6.19-rc4/dslThe only obvious problem is Vegas looks broken.
Thanks, Stephen. It seems that the default Vegas alpha parameter in the rc4 is 1... I observed similar situation with the NS2Linux simulator (with 2.6.16 code) and found that if alpha=1, delayed ack will make it broken (keeping cwnd very low without real congestion) See details at http://www.cs.caltech.edu/%7Eweixl/technical/ns2linux/known_linux/index.html#vegas (Basically alpha==1 means Vegas seeks to see a delay of about 1 packet worth. With delayed ack, 1 packet worth of delay is common even with no congestion.) To make Vegas work, I'd suggest to raise alpha to at least 2 or 3. (and beta has to be at least as large as alpha.) -David -- Xiaoliang (David) Wei Graduate Student, [EMAIL PROTECTED] http://davidwei.org *********************************************** - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
