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Re: [RFC] TCP Vegas for 2.6

To: Andi Kleen <ak@xxxxxxx>
Subject: Re: [RFC] TCP Vegas for 2.6
From: Stephen Hemminger <shemminger@xxxxxxxx>
Date: Mon, 8 Mar 2004 13:30:09 -0800
Cc: linux-net <linux-net@xxxxxxxxxxxxxxx>, netdev@xxxxxxxxxxx
In-reply-to: <20040308212156.GE26401@xxxxxxxxxxxxx>
Organization: Open Source Development Lab
References: <20040308130454.0442c04d@xxxxxxxxxxxxxxxxxxxxx> <20040308212156.GE26401@xxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
On Mon, 8 Mar 2004 22:21:56 +0100
Andi Kleen <ak@xxxxxxx> wrote:

> > +/* Vegas variables */
> > +   struct {
> > +           __u32   beg_snd_nxt;    /* right edge during last RTT */
> > +           __u32   beg_snd_una;    /* left edge  during last RTT */
> > +           __u32   beg_snd_cwnd;   /* saves the size of the cwnd */
> > +           __u8    do_vegas;       /* do vegas for this connection */
> > +           __u8    doing_vegas_now;/* if true, do vegas for this RTT */
> > +           __u16   cntRTT;         /* # of RTTs measured within last RTT */
> > +           __u32   minRTT;         /* min of RTTs measured within last RTT 
> > (in usec) */
> > +           __u32   baseRTT;        /* the min of all Vegas RTT 
> > measurements seen (in usec) */
> > +   } vegas;
> 
> How about making this and the experimental westwood stuff CONFIG_* 
> options? At least for the data structures?  Or maybe alternatively allocating
> it separately when needed only (this would avoid CONFIG_* options)

CONFIG options are of no use vendors who need to ship binary kernels.

But it might make sense to drop this for CONFIG_EMBEDDED, but I can't
see embedded kernels having lots of connections anyway.

> I remember when we made jokes about the size of TCBs of other stacks 
> compared to Linux, but we must have exceeded them all by far. The additional
> code is not really a problem, but adding all that bloat to dynamic data 
> structures adds up quickly when you have a few thousands of them, limiting
> scalability.
> 
> -Andi


-- 
Stephen Hemminger               mailto:shemminger@xxxxxxxx
Open Source Development Lab     http://developer.osdl.org/shemminger

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