From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: To: 9fans@9fans.net Date: Tue, 15 Jun 2010 22:20:23 -0700 From: Skip Tavakkolian <9nut@9netics.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Subject: Re: [9fans] Inducing artificial latency Topicbox-Message-UUID: 342a85ec-ead6-11e9-9d60-3106f5b1d025 any reason loopback(3) wont work? it has options for delay and latency. > I'm going to be doing some work with 9P and high-latency links this > summer and fall. I need to be able to test things over a high-latency > network, but since I may be modifying the kernel, running stuff on > e.g. mordor is not the best option. I have enough systems here to do > the tests, I just need to artificially add latency between them. > > I've come up with a basic idea, but before I go diving in I want to > run it by 9fans and get opinions. What I'm thinking is writing a > synthetic file system that will collect writes to /net; to simulate a > high-latency file copy, you would run this synthetic fs, then do "9fs > remote; cp /n/remote/somefile .". If it's a control message, that gets > sent to the file immediately, but if it's a data write, that data > actually gets held in a queue until some amount of time (say 50ms) has > passed, to simulate network lag. After that time is up, the fs writes > to the underlying file, the data goes out, etc. > > I have not really done any networking stuff or filesystems work on > Plan 9; thus far, I've confined myself to kernel work. I could be > completely mistaken about how 9P and networking behave, so I'm asking > for opinions and suggestions. For my part, I'm trying to find good > example filesystems to read (I've been looking at gpsfs, for > instance). > > > John > -- > "With MPI, familiarity breeds contempt. Contempt and nausea. Contempt, > nausea, and fear. Contempt, nausea, fear, and .." -- Ron Minnich