From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Netes Subject: Re: Basics of congestion control? Date: Tue, 31 Jul 2012 14:08:56 +0300 Message-ID: <20120731110856.GD2077@calypso> References: <5017A740.4020205@profitbricks.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <5017A740.4020205-EIkl63zCoXaH+58JC4qpiA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sebastian Riemer Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-rdma@vger.kernel.org Hi Sebastian, On 11:37 Tue 31 Jul , Sebastian Riemer wrote: > Hi all, > > could someone please explain what I can do with the new congestion control? > > Do I understand it right that I can influence the flow control (e.g. > amount of credits) with it so that I can avoid disruption (XmitWait, > XmitDiscardedPackets) caused by congestion? Congestion control isn't a credit based mechanism. While InfiniBand flow control is defined between two ports of the same link, congestion control is working across the fabric between a congestion point (a switch) and a reaction point (source node). Reaction point implements a Congestion Control Table that contains an array of values of injection rate delay used to control congestion. You can find more information in the IBTA LWG Errata document 3Q2010. -- Alex -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html