On Tue, 29 May 2007 23:07:00 +0300 (EEST) "Ilpo Järvinen" <[EMAIL PROTECTED]> wrote:
> On Tue, 29 May 2007, Stephen Hemminger wrote: > > > On Mon, 28 May 2007 13:27:03 +0300 (EEST) > > "Ilpo Järvinen" <[EMAIL PROTECTED]> wrote: > > > > > On Sun, 27 May 2007, Ilpo Järvinen wrote: > > > > > > [PATCH] [TCP]: Fix GSO ignorance of pkts_acked arg (cong.cntrl modules) > > > > Yes, thanks for fixing this. Wonder how it affects measurements. > > ...It's a bit hard to tell since dynamics change so dramatically > in > 0 check cases, the resulting behavior in too small value cases > may be easier to predict... It's possible that this could explain some > anomalities you've been seeing in your measurements. > > > > It is not very clear how SYN segments should be handled, so I > > > choose to follow the previous implementation in this respect. > > > > Since we don't invoke congestion control modules until after the SYN > > handshake this is not a problem. > > Just curious, do you mean that cc modules cannot measure, e.g., initial > RTT through this mechanism (though they could do that in init() cb then > I suppose)... Or do you mean that they are called already for the ACK > that completes the SYN handshake and therefore its skb is being cleaned > from the queue right now (this is the case I above refer to)? > In the first case the decrementer code is NOP. If the latter, then it > is just interface specification question, i.e., if SYNs are treated as > zero or one in num_acked for the pkts_acked callback (I have no opinion > on this but was just trying to make sure cc modules get what they > expect :-)). We don't switch a socket out of Reno until after the initial handshake. It evolved that way, and has a couple of advantages: * uncomplete connections don't up module refcount so it is easier to debug * in future, we can choose congestion control to use based on route metric. As an interface, it makes sense to keep the API with the SYN counting as a packet. -- 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
