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Questions tagged [latency]

Latency is the time period between a signal being sent and a signal being received

Latency is the time period between a signal being sent and a signal being received. In computer networking this can be the time between a sending of a packet and receiving of a packet.

To illustrate we can use the ping command:

PING google.be (173.194.66.94) 56(84) bytes of data.
64 bytes from google.be (173.194.66.94): icmp_req=1 ttl=47 time=76.6 ms
64 bytes from google.be (173.194.66.94): icmp_req=2 ttl=47 time=74.8 ms
64 bytes from google.be (173.194.66.94): icmp_req=3 ttl=47 time=79.6 ms

The latency here is 76.6 ms.

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Adding some delay to a specific port on localhost using tc and netem

I'm going to simulate a network latency on three different ports of local host by using tc (traffic control for Linux) commands. I run the following code: !/bin/bash tc qdisc add dev lo root handle 1: htb tc class add dev lo parent 1: classid 1:1…
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Why may AWS t3.micro in Singapore respond slower than t2.nano in N. Virginia from Bangladesh?

I have a t2.nano instance running in North-Virginia availability zone (us-east-1) for almost 1 year. In hope of reducing latency, I just have deployed the created AMI of that instance to a t3.micro instance in Singapore (ap-southeast-1) zone. There…
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Monitor latency by IP on a bridge-enabled host

Is there a tool which captures packets, measure latency in realtime and display it with some IP filtering options for Windows ? My particular setup : Internet -> Router -> Host Master -> Host Slave Host Master (Win7) have two ethernet cards : eth0,…
Cqke
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Brocade DCX 8510 inter DC latency - understanding OIDs to find L1 issues

Trying to determine if there is some intermittent inter DC latency on the FC links, but only have access to the OID counters for the DCX 8510. Since it is a L1 link over DWDM there are no stats from the service provider to measure any possible…
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Performance Tuning Linux

Performance Tuning/ Monitoring/Latency keeping in mind I see following 4 items & in each item they are lot of tools. CPU Memory IO Network What I see following tools we do…
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Need ultra-low latency, how to minimize?

I have several Windows Server 2008 R2 machines that act as clients and are connected to another server in the same datacenter. I don't have access to teh server. I need to minimize latency between clients and the server. They communicate via…
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Apache has a long lag before responding

I have an Apache server on CentOS that occasionally takes 1-5 seconds to serve a file, including a text file that is 2 characters. I have a JMeter test that gets a few different types of files, and the delay often happens on whatever file it grabs…
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Network Latency and Timing as shown by Chrome

I'm trying to understand why a static image being served by IIS is taking ~ 182 ms to load. Using chrome I captured the following timing information. When I request the same image by opening chrome on the web server directly, I see the "waiting"…
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Disk latency within a virtual machine

I've been looking at some performance issues on a clustered virtual machine in our organisation. Actually this problem seems to affect most of the virtual machines I have looked at. Both host and VM are 2008R2 with SP1. I believe - from what I have…
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Appropriate network monitoring tool(s) for logging hiccups

I have a customer who has problems with our software crashing from time to time. Unfortunately, if you unplug the network cable in the middle of a transaction our software will crash every time and there is nothing that can be (or at least nothing…
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Apache Benchmark is slow from public network, magnitudes faster locally. What are some things I do to speed this up?

I am testing my Linode Ubuntu 14 64bit server out, it's the most basic server available from them. I am using Apache Benchmark to test the server, as well as a multithreaded script I wrote in Python, but more on that later. Using AB I noticed I get…
scape
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LatencyTop on Centos 6.2

What do I need to do to get LatencyTop working on Centos 6.2? Does it involve compiling a debug kernel with some extra flags? Both the man page and the website are very short of information. Thanks! EDIT: I should have been more specific, sorry, my…
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Geographic testing for latency

Really struggling to find tools that report latency loading a website from multiple geo-graphic locations. Are there such tools? I have begun replicating infrastructure in other EC2 regions, but find it difficult to ascertain what performance…
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Cisco ASA Latency

What is the typical latency added when using a Cisco firewall such as ASA 5505? Are we talking less than 50 microseconds?
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tcpdump udp data capture latency

I am using tcpdump to capture UDP packets and analyze network latency between a UDP broadcaster and my server. To calculate latency I compare the source host timestamps reported in UDP application data to the tcpdump local "kernel" timestamps. The…
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