Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964971AbWHNV0b (ORCPT ); Mon, 14 Aug 2006 17:26:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964966AbWHNV0b (ORCPT ); Mon, 14 Aug 2006 17:26:31 -0400 Received: from ns2.lanforge.com ([66.165.47.211]:47297 "EHLO ns2.lanforge.com") by vger.kernel.org with ESMTP id S964971AbWHNV0a (ORCPT ); Mon, 14 Aug 2006 17:26:30 -0400 Message-ID: <44E0EA5E.30306@candelatech.com> Date: Mon, 14 Aug 2006 14:25:50 -0700 From: Ben Greear Organization: Candela Technologies User-Agent: Mozilla Thunderbird 1.0.7-1.1.fc4 (X11/20050929) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "linux-os (Dick Johnson)" CC: Linux kernel Subject: Re: Network compatibility and performance References: <44DE2A44.5070006@candelatech.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2533 Lines: 59 linux-os (Dick Johnson) wrote: > No it will return FAIL (-1) or an error and 0 (the bottom of the procedure) > if the whole things went. It is mandatory that the whole thing goes > so this procedure should handle any intermediate actions. I see..I missed that part. > Upon your advice, I may try to add select() although, on a write it > seems to be putting in user-space something that used to be handled > quite well in the kernel. I don't think the user should really care > about the kernel internals, whether or not the kernel happens to have > a buffer available. Since you put it in non-blocking mode, you need the select() to throttle unless you want to busy spin. Whether you should have to actually put in in non-blocking mode or not is a different question. >>I have no idea why you need to add the MIN() logic..and that seems like >>something that should not be required. >> > > It seems that some code 'thinks' that a large buffer of data is > an error and won't even try to send some anymore. I have seen a problem where I can repeatedly hang a TCP connection when running at high speed. The tx queue is full or mostly full, and on the wire I only see 200kpps of duplicate acks. Can't reproduce it with anything other than my big complicated proprietary app, so it remains unfixed. I am not sure if this is related to what you see or not..but could you check to see if there is lots of acks on the wire when this hang happens? >>Even 112kbps sucks on a decent network. What is the speed of your >>network, what protocol are you using, if tcp, what is the latency >>of your network? >> > > > The network is a single wire about 8 feet long, connecting Intel gigibit > links on two identical computers (crossover cable). This link is TCP. > For high-speed data, I use UDP and I get a higher throughput because > there is no handshake. Thew latency is the latency of Linux. BTW, it's > only a gigaBIT link, you can divide that by 8 for gigabytes. I don't > know the actual bit-rate on the wires, if we assume 1GHz, the byte-rate > is only 125,000 bytes per second. Being able to use 89.6 percent of > that isn't bad at all. You must be meaning to add a few more zeros to that number. If you are getting ~125,000,000 Bytes per second then you are doing OK. Ben - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/