From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nivedita Singhvi Subject: Re: [RFC] TCP burst control Date: Tue, 06 Jul 2004 19:20:59 -0700 Sender: netdev-bounce@oss.sgi.com Message-ID: <40EB5E0B.1030407@us.ibm.com> References: <200407070009.i6709wiA026673@ms-smtp-03-eri0.southeast.rr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: "'David S. Miller'" , "'Stephen Hemminger'" , netdev@oss.sgi.com, rhee@ncsu.edu, lxu2@ncsu.edu Return-path: To: Injong Rhee In-Reply-To: <200407070009.i6709wiA026673@ms-smtp-03-eri0.southeast.rr.com> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org Injong Rhee wrote: > Hi David and Stephen, > > We tested this rate halving. In fact, rate having in fact degrades the > performance quite a bit. We can send you more information about it. Our test > indicates that this feature introduces many timeouts (because of bursts), > and also cause unnecessary cwnd backoff to reduce the transmission > unjustifiably low -- so there are many (I will repeat, many) window and > transmission oscillations during packet losses. We fix this problem Could you point me to a paper or summary of your info? > completely using our own special burst control. It is very simple and easy > technique to implement. If you need some data to back up our claims, I will > send you more. Once we implemented our burst control, we don't have any > timeouts and not much fluctuation other than congestion control related. > Currently with rate having, current Linux tcp stack is full of hacks that in > fact, hurt the performance of linux tcp (sorry to say this). Our burst > control, in fact, simplifies a lot of that and makes sure cwnd to follow > very closely to whatever congestion control algorithm is intended it to > behave. The Linux Reno burst control in fact interferes with the original > congestion control (in fact, it tries to do its own), and its performance is > very hard to predict. Can you characterize the workload/traffic/error rate that each would be best suited for? thanks, Nivedita