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Re: Improving timer resolution

Hello all,
As part of a course an NTUA team has used the UTIME patch to provide improved time
accuracy to the TBF qdisc. I attach you the modified sch_tbf.c file. The
implementation can be improved since it uses interer division to calculate the
shaping distance but anyway it demonstrates the feasibility of this option.

jamal wrote:

> On Mon, 20 Nov 2000, Rui Prior wrote:
> > Hello.
> >
> > All non-work-conserving queuing disciplines are severely limited by the
> > timer's resolution. Even pushing HZ to 1024 doesn't seem to be enough for all
> > of todays networking demands.
> > Wouldn't it be possible/practical to make something like the utime patch
> > included in kurt (see http://www.ittc.ukans.edu/kurt/) into the standard
> > kernel and then use it for proper support of software rate control?
> > It could very well be an optional configuration item, so regular hosts
> > wouldn't suffer the overhead.
> >
> *Clock sources are already there, timers are not.
> [include/linux/net/pkt_sched.h]
> Other than ukansas there is also an effort somewhere in Germany for higher
> resolution timers. You will find that Linux has other events which also
> trigger checks (such as packet arrivals) and so is not totaly dependent
> on timers.
> Why its not in there? Maybe someone else can answer this. Werner?
> cheers,
> jamal

Panagiotis G.Stathopoulos
National Technical University of Athens
Telecommunications Laboratory
E-mail: pstath@telecom.ntua.gr
Tel: +30 1 772 1495     Fax: +30 1 772 2534