[altq 88] Re: When a class is delayed (undertime)

[Fulvio Risso <F.Risso@cs.ucl.ac.uk>]

Hello.

You are right, but the original code (before the 18th June patch) subtracted

>         -((1 - RM_POWER) * cl->avgidle_) >> RM_FILTER_GAIN,

from all packets.

	fulvio



> -----Original Message-----
> From: owner-altq@csl.sony.co.jp [mailto:owner-altq@csl.sony.co.jp]On
> Behalf Of Lin Su-Mei
> Sent: Monday, August 09, 1999 9:07 AM
> To: altq
> Cc: G Muthukumar; Kenjiro Cho
> Subject: [altq 85] Re: When a class is delayed (undertime)
> 
> 
> 
> I somehow agree with what Muthu said. Please check (Appendix A1 of "Link
> sharing and resource management models for packet networks).
> For a nonregulated class with avg negative, the time_to_send(undertime) is
> set to make the next avgidle become 0.
> But for a regulated calss with avg negative, the link-sharing 
> scheduler sets
> the undertime field for the class to f(s,b) (for minburst > 1, should be
> offtime)  ahead of the current time. A regulated calss is never restricted
> by the link-sharing scheduler to less than its allocatd bandwidth,
> regardless of the "excess" bandwidth used by that class in the 
> past. And in
> the middle of A.3 in the same paper it says, the link-sharing 
> scheduler sets
> the time-to-send field for a regulated class to f(s,b)=s/b (for minburst >
> 1, should be offtime) secondes ahead of the current time. .....at 
> that time
> the general scheduler is allowed to send a packet from that class 
> regardless
> of the value of avg.... . If the class is still overlimit after a 
> packet is
> ent, then the time-to-send field is again set to f(s,b)=s/b 
> seconds ahead of
> the current time.
> So I also feel that this code
>   TV_ADD_DELTA(&cl->undertime_,
>         -((1 - RM_POWER) * cl->avgidle_) >> RM_FILTER_GAIN,
>         &cl->undertime_);
> 
> in rmc_delay_action()needs to be retained so that this regulated 
> class will
> not be ponished by the bandwidth it used before.
> 
> lsm