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

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310 views

Latency, Nginx & PHP-FPM

I have a high load dynamic PHP web service which I have recently moved from Apache2 to Nginx and PHP-FPM. I am finding that the average request latency has increased from 0.5s to 1s since the move. ...
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1answer
174 views

35 times increased latency between data send rate of 1 millisecond vs 100 microseconds. WHY?

Experiment hping -S --data 100 -c 100 10.56.1.2 -i u100 round-trip min/avg/max = 0.5/14.0/15.8 ms hping -S --data 100 -c 100 10.56.1.2 -i u1000 round-trip min/avg/max = 0.3/0.4/4.8 ms Observation: ...
6
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1answer
3k views

Limit incoming and outgoing bandwidth and latency in linux

I realise many similar questions have already been asked, but so far I've yet to find a solution to my problem. I have a virtual linux server (running Debian Squeeze) that I use for testing of ...
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0answers
81 views

how to determine whether network switching equipment latency is OK for VDI delivery?

Is there a good (proper) way to test whether network switching in place is good enough for VDI delivery? I read a Cisco UCS whitepaper that stated that they observed 3.2 ms latency across their test ...
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0answers
227 views

FTP Transfers Slow Between 2 Servers

Between 2 dedicated servers, hosted in 2 different DCs (different companies), the FTP upload speeds are always much slower than the max connection speed. Specs: Windows 2008 on both. Quad core/8 GB ...
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1answer
3k views

High latency/drops between Cisco switches in two locations. How to troubleshoot?

I'm receiving user complaints about poor network application performance between two parts of a large warehouse facility. The software is a curses-based terminal application running on a Linux server. ...
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2answers
3k views

sssd and ldap authentication cache

On our box running OpenSUSE 12.2 we have installed OpenLDAP and sssd daemon. We are using these two services for user authentication. Recently we created a script which creates new web-users for our ...
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3answers
801 views

Measuring network latency

I want to measure performance of the network, especially latency. We are performing stress tests of a system that sends live audio / video data over the network. When there are multiple simultaneous ...
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1answer
116 views

Best practices on lowering latency between two endpoints [duplicate]

I would like to know what tools or what kind of calculation should be made in order to find the lower latency possible between two points physically distant. For example: Ping time from Europe to ...
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0answers
36 views

reduce initial SSH communication messages

The situation: we have some manager servers in Japan which connects to servers in Amsterdam. Since the latency between JP and EU could reach 300ms, the initial login can take up to 6 seconds. Although ...
0
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1answer
64 views

Effect of latency on page load

What effect can a latency of 100 ms have on a page load time? If a 100 KB file is served from two locations with latencies of 100ms and 200ms respectively, will the difference in load time be just ...
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2answers
100 views

Trans-atlantic VOIP

We're a Canadian business on the east coast and will soon be opening up a new call centre in Australia. This new call centre will be handling our graveyard shift and will be overlapping with the ...
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1answer
141 views

Low Latency for Google compared to servers located with in my country [closed]

When i ping google.co.in its showing 11.1 ms as average ping www.google.co.in PING www.google.co.in (173.194.36.63) 56(84) bytes of data. 64 bytes from bom04s02-in-f31.1e100.net ...
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0answers
225 views

Amazon's ELB + Instances = High Latency?

I have a single instance running which is sitting behind their load balancer. When I use apache's benchmark utility and point it at the instance the response time is more often than not, under 50ms. ...
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2answers
408 views

Remote Desktop Software with low latency for thin clients [closed]

I'm currently using a thin client with the following specification: I am searching for Remote Desktop software that will allow me to have a very low latency for audio quality on my thin clients. ...
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2answers
2k views

Can VPNs reduce latency? [duplicate]

I've found a common subject in forums asking about using VPNs to reduce latencies between the gamers and the game servers. I've even found some blog posts confirming this. From my understanding, ...
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3answers
533 views

How to compare RDP latency?

For a remote Windows desktop solution, accessed from Las Palmas de Gran Canaria, I want to evaluate various options. What currently comes into my mind: EC2, Ireland Azure Virtual Machine, Ireland ...
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2answers
311 views

Why my server request takes 28 Second to get response?

I have a Wordpress website on a Godaddy server having at http://kerala.letmeshare.org. When I request to get this website this takes almost 28 sec to get reply. Because of this I made a complete ...
0
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1answer
332 views

Extremely high apache 2 initial response time, no system load

I've noticed recently that a VPS that I administrate has some strange Apache behaviour. Essentially, any HTTP request hangs for about a second before it is actually served. Output from ab shows ...
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2answers
301 views

Raid 1 and Latency

I am aware that RAID comes with certain write penalties, etc and that varies at different levels. I am trying to figure out how latency is affected in RAID 1. From my SAN, I can look at the number of ...
1
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1answer
365 views

What could this extra 50ms latency be on my unbound DNS resolving server (Fedora)?

I have a discrepancy in query latency. It's not a problem, it's just strange enough to worry me. Client machine (Fedora 18) runs unbound-1.4.19-1.fc18.x86_64. Server machine (Debian 7 testing) runs ...
0
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1answer
160 views

How do I calculate the ethernet NIC-to-NIC time to send a MTU packet (1500 bytes)? (OS-excluded) [closed]

I understand it will depend on the speed of the ethernet 10 Mbit to 100 Gbit. Given an ethernet speed, how do I calculate the time spend in the wire from NIC-to-NIC? I am assuming here that the ...
1
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1answer
397 views

Exchange Database Write Latency and ActiveSync - correlation?

We have an increasing number of ActiveSync devices connecting to our Exchange 2010 infrastructure (one primary mailbox server with about 920 accounts and counting; plus a cas/hub in the primary site). ...
0
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1answer
57 views

Adjust drive latency/lag on Server 2008 server with an array?

Got a 2008 server in production , which currently has "one" disc. (Actually a SAS array, presented as a single disc to the OS.) This "disc" is partitioned into a few sections, with some free space ...
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0answers
251 views

Network latency in Ubuntu 12.04 LTS

Until recently, my internet connection on my Ubuntu machine was working fine. Then, seemingly out of nowhere, I'm finding severe latency problems. For instance, in my web browser, I'll attempt to ...
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1answer
345 views

What is a “Latency Outage”? [closed]

I'm one of many customers of Windstream, the only internet provider in my area, and just after having hit the 1-year mark of being a customer, my 10M internet connection became about a 512k ...
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1answer
356 views

Ultra Low Latency Linux Distribution or Kernel [closed]

I'd like to know if there are any linux distributions that are focused on low latency networking. The area I'm working in is algorithmic trading, and extremely low latency comms between machines is a ...
0
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1answer
321 views

Why do these ipfw delayed pipes have no effect?

I'm on OSX 10.7.5 and am attempting to add some latency to the connection to my personal domain with ipfw, using this article as a guide. Normal latency: > ping -c5 troutwine.us ...
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2answers
812 views

Should I enable “Intel NIC DMA Channels”?

I have HP DL360p Gen8 646902-xx1 I'm trying to optimize my config for low latency trading. Should I enable "Intel NIC DMA Channels"? Will that help/affect my system? From HP doc: Added a new ROM ...
3
votes
1answer
482 views

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, ...
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0answers
113 views

Website latency and bad tcp packets

I have multiple websites hosted on a Linode VPS and I'm having an issue with one of them: every page that I try to load has about 10 seconds latency. Apache logs are clean and the other websites on ...
0
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2answers
552 views

High latency issue for web service call from amazon aws ec2 to local server

We have a legacy web application that is running in our data center on premises located in Houston. We have a developed a new .net 4 based web application in order to provide new features to ...
4
votes
1answer
6k views

How to troubleshoot latency between 2 linux hosts

The latency between 2 linux hosts is about .23ms. They are connected by one switch. Ping & Wireshark confirm the latency number. But, i dont have any visibility into what is causing this latency. ...
0
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1answer
274 views

What exactly is cut-through latency?

This switch datasheet specifies that the "cut-through latency" is 300ns. What exactly does "cut-through latency" mean? Is it: The difference in time between a packet's head entry and that packet's ...
7
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3answers
429 views

TCP Window Scaling for Satellite Connections

A satellite connection generally has a RTT around 500ms. Connections generally suffer sub-optimal transfer speeds, in spite of large amounts of bandwidth because TCP acknowledgements take too long to ...
7
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2answers
4k views

Data obtained from ping: is it round trip or one way?

I have 2 servers, each in two separate locations. I need to host an application on one, and the database server on the other. From the app server, if I ping the database server, on average I get ...
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2answers
213 views

Diagnosing network latency issues

I have two servers both with gigabit network cards that were experiencing severe latency issues communicating with one another. The culprit eventually turned out to be that one of the servers was ...
2
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1answer
108 views

Performance issue in using Amazon S3 for run-time updates

I have a web application hosted in Amazon EC2 as well as in Rackspace. Users can upload files through this application and also modify them. Those files are stored in local storage in each of these ...
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3answers
173 views

Is this a latency issue or something else?

I have what I think may be a latency problem. I have a magento installation on a shared host. I know it's best to run magento on a dedicated server but it's early days and it's a good host. When I ...
0
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1answer
249 views

Latency and bandwidth limitation(WAN Emulation)

I have a requirement to emulate the impact of a new application on the WAN. The WAN bottleneck is a 65MB dedicated pipe between Australia and the UK. I have a setup to generate the traffic, but to ...
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2answers
97 views

Impact of Traffic through the first NIC on the second NIC

I have two NICs on a RHEL 6 server. They are both set at 1GB/sec full duplex. The first NIC has lots of small (< 100 byte) TCP socket writes. The second NIC is used to receive a 50 MB/sec TCP input ...
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0answers
26 views

Impact of Traffic through the first NIC on the second NIC

I have two NICs on a RHEL 6 server. They are both set at 1GB/sec full duplex. The first NIC has lots of small (< 100 byte) TCP socket writes. The second NIC is used to receive a 50 MB/sec TCP input ...
2
votes
2answers
283 views

Cross-cloud deployment: Servers on azure - Mongodb at MongoHQ (AWS) - known pitfalls?

Looking to deploy an existing Mongodb-backed solution to the cloud for a client. I'm hoping to combine MongoHQ and Azure to use the simplest possible Mongodb deployment together with the simplest ...
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votes
2answers
830 views

Does a 150ms latency is good enough to launch a product (USA hosted in Europe)? [duplicate]

Possible Duplicate: Can you help me with my capacity planning? Having worked for weeks on a new mobile app product, we are finally preparing a public launch in the coming weeks. However we ...
0
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1answer
322 views

How to reduce DNS server latency?

Which is the best practise to reduce DNS latency? I'm using the beautiful powerdns DNS server, and i would like to lower down latency between internet client requests and the DNS server response. I ...
0
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2answers
471 views

Why is the latency on one LVM volume consistently higher?

I've got a server with LVM over RAID1. One of the volumes has a consistently higher IO latency (as measured by the diskstats_latency munin plugin) than the other volumes from the same group. As you ...
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2answers
940 views

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. ...
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2answers
86 views

I need to test the ballpark connection latency between two states - Any sites or easy ways to do this?

I am in Kansas I need to test latency to Oregon. Assuming I don't know anyone in Oregeon or know what hosts are pingable and also in oregeon is there any handy tool for this? It would be even better ...
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3answers
838 views

Tool to test MySQL latency [closed]

I want to compare the latency of my web application against two different MySQL servers: one a local machine and one hosted via Amazon RDS. What would be a good, free, and (preferably) easy tool to ...
5
votes
1answer
277 views

Hardware/topology recommendations for low latency UDP network

I'm setting up a LAN comprised of 60 end nodes that are receiving a high volume of UPD datagrams from one master server. The server sends 60 unique datagrams every 100ms, each datagram is 64 bytes. ...