On Tue, 31 Oct 2006 15:25:16 -0800 "Xiaoliang (David) Wei" <[EMAIL PROTECTED]> wrote:
> 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/dsl > > > > The 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 > I ran with the current default: alpha = 1 (scaled 2) beta = 3 (scaled 6) gamma = 1 (scaled 2) -- Stephen Hemminger <[EMAIL PROTECTED]> - 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
