From mboxrd@z Thu Jan 1 00:00:00 1970 From: Baruch Even Subject: Re: [PATCH] Too aggressive cwnd backoff Date: Fri, 08 Apr 2005 22:33:58 +0100 Message-ID: <4256F8C6.40704@ev-en.org> References: <20050407164146.GA6479@ev-en.org> <20050407101653.2cc68db1@dxpl.pdx.osdl.net> <42557895.8040004@ev-en.org> <20050407113121.31b71a94.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "David S. Miller" , shemminger@osdl.org, netdev@oss.sgi.com, werner@almesberger.net Return-path: To: John Heffner In-Reply-To: Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org John Heffner wrote: > This test looks correct to me. (We never touched it.) It is the bounding > parameter specified in rate halving. If you actually get down that far, > then rate halving is getting confused, though. In my tests with either NewReno at high-BDP network settings (300Kbit/s, 120ms delay, BDP = 3200 packets), we always go into this confused mode. It will always upon a drop go to a point between the one-half and one-quarter of the original cwnd, but then, due to performance problems at that point the queue is filled and lots of packets are getting lost in bursts after I disabled throttling, with throttling it goes even below one quarter. If I understand you correctly this check (that I changed) is correct and should not be changed but rather that the bug is elsewhere. I'll give it another look when I have some more time. Baruch