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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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Microwave Link Latency

An internet provider installed us a microwave link: The issue is that: The ping from our side to the gateway is about 1-2 ms, which is great, but it remains like this for only 12 hours, then it start to give latency and time outs 100 - 800 ms. The…
MohyedeenN
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Simulating latency to a URL using ipfw

How can I simulate latency to a single URL? I tried following to simulate latency to a single URL by adding a ipfw rule. sudo ipfw add pipe 1 ip from myurl.com to any #(response of running above command) 00100 pipe 1 ip from any to any sudo ipfw…
user199801
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how to disable MSI on tg3 driver?

got some new HP DL380p G8 for Centos. What's the correct options to disable MSI for the onboard Broadcom NICs? I tried disable_msi in modprobe.conf.local and it doesn't work. Thanks Will
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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. I'm not sure where the bottleneck in the system…
sungiant
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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 RAM/1 Gbit network care FileZilla FTP Server Both…
SilentSteel
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Bandwidth throttling software

I need to be able to simulate high bandwidth/high latency/high packet loss on my pc for the purpose of testing the software that I'm writing. I've seen some software that you can install on a separate machine that will act as a throttling…
Steven Evers
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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. When I point ab at the load balancer the response…
Joe O
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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 unbound 1.4.17-2. Both are connected to the same…
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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). Solarwinds has been frequently throwing…
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Ultra Low Latency Linux Distribution or Kernel

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 must. The current h/w we're using is 10g…
Zanlor
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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 Based Setup Utility (RBSU) Advanced Performance Option…
Oleg Vazhnev
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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 the same machine are running well. At a first…
Mistero Lupo
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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 can see, the dark orange /root volume has…
David Schmitt
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What latency can I expect with SDSL?

My company is considering moving some internal infrastructure to my location, that will be accessed, over vpn, from other company locations. Currently we are reluctant to do this because of the network quality in my location (ADSL 2+, 20Mbit /…
Magnus Akselvoll
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Need help troubleshooting highly variable ping times

I'm at work using Citrix (think Remote Desktop) to connect to client sites. With my job I have to write a fair bit of code while I'm connected remotely via Citrix, so the latency of my internet connection is important. If I'm getting ping times…
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