Re: link is broken

[Lloyd Wood <L.Wood@surrey.ac.uk>]

On Tue, 26 Oct 1999, Shu Yuan Chang wrote:

> hi there,
>    could anyone kindly tell me where to find those files URLed in the
> followling
> link, the hyperlink is broken?

add a base href of 

http://www-mash.cs.berkeley.edu/cgi-bin/cvsweb/ns-2/

to the partial URLs given.

As for haobo's stuff, isi.edu links are always broken; I haven't been
able to find Kannan's directory in ages, for example...

L.

>   thanks!
> 
> Shu
> 
> 
> Haobo Yu wrote:
> 
> > In this email I'll briefly explain a lesson we learned from tuning
> > the memory usage of a large-scale (wrt traffic) simulation. Hopefully
> > it'll be useful for others. Here ns is referred to the current snapshot.
> >
> > Originally tcl/ex/large-scale-web-traffic.tcl was a self-similar web
> > traffic model used in "Dynamics of {IP} Traffic: A study of the role of
> > variability and the impact of control", SIGCOMM'99. It was implemented
> > completely in otcl (tcl/http/http-mod.tcl). When there are 400 HTTP
> > sessions and with the parameters given in that script, its memory usage
> > linearly increases with time, and the simulation ends with about 800+MB
> > memory (see http://www.isi.edu/~haoboy/old-usage-400.ps).
> >
> > There are two factors that contributed to this. First, http-mod.tcl
> > allocates various split objects using 'new', but does not _explicitly_
> > 'delete' them in otcl. It turns out that this caused a memory leak every
> > time that new-ed split object is reassigned a value. Second, implementing
> > things, including HTTP pages, objects, completely in otcl takes a lot of
> > extra memory than to maintaining those complex data structures in C++.
> >
> > After redesigning the HTTP traffic model and implementing the data
> > structures completely in C++, we cut down memory usage to be stabilized
> > around 62MB for a 400 session simulation
> > (http://www.isi.edu/~haoboy/new-usage-400.ps).
> >
> > However, a sad news is, moving things into C++ does not help much in
> > reducing executaion time. This is because packet passing in ns is
> > completely done in C++, and that's the main cause of the long execution
> > time (assuming there's enough memory).
> >
> > The lesson we learned is: (1) be very careful about 'new' and 'delete'
> > about split objects, and (2) always maintain complex data structures in
> > C++.
> >
> > Hope this will be helpful for others.
> >
> > - Haobo

<L.Wood@surrey.ac.uk>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>