I'm doing some performance tuning and capacity planning for a low-latency application and have the following question: What is the theoretical minimum round-trip time for a packet sent between a host in London and one in New York connected via optical fiber? ...
I have an application which obtains data in JSON format from one of our other servers. The problem I am facing is, there is is significant delay when when requesting for this information. Since a lot of data is passed (approx 1000 records per request where each record is pretty huge) is there a way that compression would help reducing th...
I've written a 'server' program that writes to shared memory, and a client program that reads from the memory. The server has different 'channels' that it can be writing to, which are just different linked lists that it's appending items too. The client is interested in some of the linked lists, and wants to read every node that's added ...
Hello How could I measure a latency of mutex, semaphore or futex? I mean the latency between two events: unlock previously locked mutex and the locking that mutex. There are two cases: when all threads/processes are on the same CPU (how long will it take to reschedule thread) and when first thread is on the first CPU and second is on se...
Hi folks, I have a list of server IP addresses, I need to check if each one is online and how long the latency is. I haven't found any straight forward ways of implementing this, and there seems to be a few problems in calculating latency accurately. Any ideas? ...
I have a 'server' program that updates many linked lists in shared memory in response to external events. I want client programs to notice an update on any of the lists as quickly as possible (lowest latency). The server marks a linked list's node's state_ as FILLED once its data is filled in and its next pointer has been set to a valid ...
I'm building a .NET remoting client/server that will be transmitting thousands of files, of varying sizes (everything from a few bytes to hundreds of MB), and I'd like some feedback on the best method for achieving this. As I see it, there are a couple of options: Serialize the entire file into my remoting object and transmit at all at...
I'm interested in using Berkeley DB replication to cache some data on some server nodes. What kind of update latency can I expect to see among the nodes? These will all be locally networked nodes. ...
Hello, I have a Java app, connecting through TCP socket to a "server" developed in C/C++. both app & server are running on the same machine, a Solaris box (but we're considering migrating to Linux eventually). type of data exchanged is simple messages (login, login ACK, then client asks for something, server replies). each message is a...
I am contemplating creating a realtime app where an iPod Touch/iPhone/iPad talks to a server-side component (which produces MIDI, and sends it onward within the host). When I ping my iPod Touch on Wifi I get huge latency (and a enormous variance, too): 64 bytes from 192.168.1.3: icmp_seq=9 ttl=64 time=38.616 ms 64 bytes from 192.168.1.3...
Hello What are sources of latency in process of sending/receiving tcp/udp packets in linux 2.6 ? I want to know a latency sources in "ping-pong" latency tests. There are some rather good papers of ethernet latency, but they cover only latency sources in the wire and switch (and rather cursory, only for specific switch). What steps of...
Hello Is there a good overview of tcp data path in Linux (2.6, not 2.4 if the path actually differ)? Where is a packet on different stages of tcp/ip stack handling? How packet is packed to tcp segment, then ip packet. How it is transmitted to network card? (with series of I/O regs write and DMA?) Is it transmitted to network card in th...
Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE ne...
I have an embedded Linux system running on an Atmel AT91SAM9260EK board on which I have two processes running at real-time priority. A manager process periodically "pings" a worker process using POSIX message queues to check the health of the worker process. Usually the round-trip ping takes about 1ms, but very occasionally it takes much...
I am trying to measure latency to a server that I don't control. This is in a colocated environment, so the latency is on the order of 500 us (.5 ms). I understand that Cisco gear frequently deprioritizes ICMP traffic, making ping times unreliable. Is there a way for me to tell if this is the case on the gear I am traversing? Can I...
Are there any protocols, systems, etc. experimental or otherwise designed for allowing normal (as normal as can be) network operations (E-mail, DNS, HTML, etc.) over very high latency links? I'm thinking of minutes to an hour, or maybe two. Think light speed lag at a solar system scale. As a side note: research or speculation on the s...
I'm writing a latency sensitive app that in effect wants to wait on multiple condition variables at once. I've read before of several ways to get this functionality on Linux (apparently this is builtin on Windows), but none of them seem suitable for my app. The methods I know of are: Have one thread wait on each of the condition variab...
Hi, I have a C++ application running on windows xp 32 system sending and receiving short tcp/ip packets. Measuring (accurately) the arrival time I see a quantization of the arrival time to 16 millisecond time units. (Meaning all packets arriving are at (16 )xN milliseconds separated from each other) To avoid packet aggregation I trie...
Only thing I found is QoS statistic in NetConnection.info, but it does not contain any kind of latency values. In red5 API "IConnection.getLastPingTime()" exists, is it accessible over standard Flex API or I need to poll it by RMI calls? ...
My latest project is using a javascript framework (jQuery), along with some plugins (validation, jquery-ui, datepicker, facebox, ...) to help make a modern web application. I am now finding pages loading slower than I am used to. After some js profiling (thanks VS2010!), it seems a lot of the time is taken processing inside the framewor...