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Questions tagged [latency]

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

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44 views

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:...
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1answer
78 views

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 ...
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0answers
72 views

What is a “normal” latency/performance of inserts on mariadb or mysql?

Hadn't used MySQL family for years. Now need to move from OracleDB to either MariaDB or PostgreSQL. So on a similar "hardware" (Openstack VM: RHEL 7.3, 4HT cores of 2.5GHz Xeon E312xx, "local" SAN &...
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3answers
108 views

Is RTT theoretically the same regardless of ping origination?

Let's say you send a ping from device 1 to device 2. The result would give you the RTT. Theoretically speaking (because many variables are realistically in play), would the RTT be the same by ...
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0answers
53 views

~1300ms latency touching file on nfs mount

I have an NFS mount where the server is on the same subnet as the client. When I time touch testempty from the client, I get: touch testempty 0.00s user 0.00s system 0% cpu 1.325 total The time ...
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1answer
33 views

Building reliable internet speed test tools

I'm interested in building a command-line speed test tool similar to the one used here. I started using it in a cron job to automatically check and record speeds at different times when we started ...
0
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1answer
112 views

How to control AWS Elastic Beanstalk auto scaling based on average response times if one endpoint is expected to take circa 60 seconds

We auto-scale our Elastic Beanstalk Java Application based on the average response times exceeding 3 seconds. When this happens we add 2 instances to our environment. Once we are back within 1.5 ...
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1answer
69 views

ICMP maximum delay between echo request and reply sustained by a router NAT

I was trying to slow down network on my server (arch linux vm) with netem sudo tc qdisc add dev eth0 root netem delay 1600ms With 1600ms delay client doesn't receive the echo reply packet though the ...
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0answers
14 views

TCP delays after spike - receives 1460 bytes every two minutes

I am seeing a strange behavior with a TCP connection. I've a sender which sends data in spikes. After the spike, the receiver starts seeing 1460 bytes every two minutes, even though the sender has ...
5
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2answers
353 views

Linux TCP/IP tuning for low throughput network?

I have two linux machines connected by a radio modem. The bandwidth is about 2kbps, with ping times of around 400ms (5% packet loss). Currently, ssh sessions have a delay in the order of 5 seconds, ...
2
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0answers
114 views

vCenter to vCenter transfers slow over 10Gbps 80ms link

We have two datacentres either side of the Atlantic with a 10Gb VPLS connection between sites with 80ms latency and better than 0.0000001% packet loss. When moving VMs between datastores on either ...
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1answer
42 views

Should things like database performance be included in a healthcheck

I manage a webservice and it is very important for my company to detect and notify if any of the services is down, and also if any of the operations it does is taking too long to respond. Until now ...
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0answers
17 views

Server selection for low latency [duplicate]

Basic Question: "Help for server stats and what I need?" Background: I'm setting up a website for someone that currently receives (on their site ATM) 15-20 users at a time and around 150 users a ...
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0answers
298 views

Ping latency between 2 directly connected PCs

I have a lot of experience with PCIe, some with USB, and little with Ethernet, so the following has got me confused: I'm evaluating the performance of a USB-to-Ethernet controller, vs a PCIE-to-...
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1answer
495 views

Multi-host VM/Docker network communication is SLOW, any best practice?

VM-1 on host-1 <[cable]> network router <[cable]> host-2 with VM-2 If I understand correctly, in case of file transfer from application on VM-1 to same application on VM-2 the data will ...
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0answers
59 views

aws ec2 windows iis latency for bigger size page sometimes

I'm experimenting with hosting a website in IIS on aws ec2, and I'm profiling it, and logging server response times using miniprofiler (used/created by stackexchange) also I'm looking at chrome dev ...
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1answer
27 views

need for CDN for website in one small country?

I sometimes make websites for businesses that trade only within the UK. If I am only interested in visitors from within the same country where the origin server is based, and the country is relatively ...
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0answers
86 views

IO Latency - Cause or symptom?

Our application (LAMP) worked perfectly at our current VPS provider. Since few weaks ago we are experiencing very high load peaks (80+). We discovered that the CPU and memory are both normal during ...
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1answer
78 views

Reduce latency between USA users from EU server [closed]

I'm in a pickle. I had thought my server was in Canada, but turns out it is in France. I don't have the time for a server migration right now (it's the end goal as 75% if the visitors are USA). Using ...
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1answer
71 views

How can I measure network latency of an Win32 application? [closed]

I have a Win32 application that connects to a server (whose IP is known) on specific ports. Is there a way to constantly monitor the latency (in milliseconds) of the packets send and received, and ...
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2answers
4k views

What is the minimum gigabit Ethernet latency I can expect? [closed]

I have 2 servers sitting in a rack running Ubuntu 16.04 with a 1 meter Ethernet cable between them, both having standard Intel Ethernet adapters. The ping between the two is about 300 us (...
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0answers
76 views

HTTPS over high-latency network

I'm building a web application that will be used in some remote parts of the country, normally with pretty awful options for internet access, usually satellite-based. Satellite internet generally has ...
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0answers
79 views

RDP latency optimisation on worldwide connections

I'm wondering how bigger companys are working around this challenge. Our company gets bigger and therefore we're starting to expand in new countries. Now a new branch office opened straight at the ...
1
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1answer
865 views

Munin Disk Latency Alerts

I have setup my Munin server and alerts and have tested them aswell. I have set the alerts for disk usage as under: df._dev_mapper_centos_root.warning 90 df._dev_md126p2.warning 90 df._dev_md126p1....
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7answers
10k views

Speed up SFTP uploads on high latency network?

I'm trying to transfer a set of large files internationally using SFTP, but I am finding my international partner can't get upload speeds above ~50k despite very good connections on either side. We ...
1
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1answer
270 views

Experiencing high latency with server without any server load nor local router latency

I am experiencing a very weird issue and it is hard to synthesize in a simple sentence, so I am sorry if the title of the question is rather shady. So I have a dedicated server running with the ...
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1answer
164 views

Receiving delayed emails, could it be my domain or MX records if not what else?

I noticed that when receiving emails on my domain they come delayed compared to another domains i have tested. The emails are being forwarded from a google email to two different addresses most of ...
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0answers
38 views

High latency when connecting HP Server with SBS2011

i have a latency issue with a HP Proliant server running SBS2011. Notes Take server off the network internet runs smoothly with no latency. Introduce server to network internet becomes slow and ...
0
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1answer
1k views

Windows file server got slow response and high latency even ping localhost by running about 7 days after rebooting

We have a file server of Windows Server 2012 R2 on DELL PowerEdge R720, and get a very weird issue in recent days about network/disk performance. The box have a RAID-1 disk group for OS (disk0) under ...
0
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1answer
183 views

Experiencing lower inter-rack ethernet speed compare to that of intra-rack

I have a cluster with 32 machines. The first 25 machines are on the first rack and the rest 7 machines are on the second rack. Each rack has a 1Gbps Ethernet switch. The network communication between ...
1
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1answer
282 views

SSHD, NTPD slow to respond

My server has been responding very slowly ever since I put it into production, however it's not slow how you might think. When I SSH to the physical virtualization server I receive the typical login ...
1
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1answer
162 views

MySql high latency

I try to connect with PHP to a MySql Server and it took in average 2 seconds to establish the connection. We host our Database in Germany (Frankfurt) and the PHP-Application in Singapore. We're ...
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2answers
48 views

Is network delay up always the same as network delay down?

If I have a client-server architecture, is the up delay (from the client to the server) always the same as the down delay (from the server to the client)? On a case-by-case basis of latency ...
6
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2answers
253 views

Latency on a small Linux NFS4 client/server system

We are a computer science department at a small university, running a RHEL 7 server using NFS4 and Fedora 24 clients (~40 client machines, ~150 users--rarely concurrent). We are having latency ...
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0answers
186 views

CPU & Memory Reservation in vSphere & Numa concept

by googling/studying vSphere documentation I have found the possibility to use "Reservation" concept in vSphere. What it is not clear to me is : CPU and Memory reservations are configured separately ...
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2answers
60 views

Should traceroute be used to diagnose network latency issues?

I ran the traceroute command from Server A to Server B, two of the hops display a latency between 250ms to 480ms. However when running ping from Server A to Server B, the response is always within ...
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3answers
4k views

Measure total latency of SSH session

Is there a way to measure/report the overall latency in a tunneled SSH session? My particular setup is: Client (OS X + wifi router + ADSL modem) Gateway SSH server exposed to Internet Internal SSH ...
0
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1answer
123 views

Hunting for performance-reducing issues on a high-usage server

I host a server through the Google Compute Engine for various purposes, most notably a Minecraft server, and it receives a lot of traffic and usage. We're talking fairly constant CPU usage at 150%, 50 ...
2
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0answers
1k views

How to measure latency using wireshark

I'm trying to measure the wire-to-wire latency of a blackbox application. The application engages in tcp offloading (kernel bypass), it consumes incoming UDP packets via a NIC and in response, ...
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3answers
78 views

Relation between distance and packets travel time

Is there a theoretical estimation for the time needed for a packet to travel from point A to point B? For example 100 ms for every 100km ? I want to estimate the difference of time needed for a device ...
8
votes
2answers
303 views

Higher TCP latencies in the latest versions of Linux

In my research group, we recently upgraded the OS on our machines from Red Hat 6.2 to Debian 8.3 and observed that the TCP round trip time through the integrated Intel 1G NICs between our machines had ...
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votes
1answer
218 views

WIndows is not following TcpAckFrequency settings

This is a wierd one. I have set the tcpackfrequency to 2 and windows does not seem to honor it no matter what I do. I would need your help with this. My current template is Internet and congestion ...
2
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0answers
38 views

Tradeoffs between cross-cloud and cross-AZ-single-cloud deployments

We have a educational system (federated microservices that are running mostly on AWS EC2, RDS MySQL and a message queue) that is already distributed across regions, primarily for latency hiding, ...
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1answer
76 views

Measure latency using ping from a 3rd server

I am new to networking and I wanted this kind of environment. is there any way to measure network latency using ping between two hosts, given the condition you are not logged into either of the hosts? ...
1
vote
1answer
691 views

TCP retransmission delays - lost acks

Maybe somebody will be able to help me out with this. I'm trying to find out if there is anything that can be optimized server-side to reduce delays in case of packet loss. Environment: Windows 2012 ...
0
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1answer
670 views

Can high server's CPU usage cause high ping for clients? [closed]

Some users have high ping and they cannot play my multiplayer game due to it. My server application is causing CPU to always rise little by little and when I restart it, it drops. I am working on ...
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0answers
119 views

How do I reduce private network latency below 0.5ms?

We are migrating from one host to another. Our cluster consists of 10 dedicated linux servers which must communicate on a private network. At the old host we observed latencies below 0.2ms between our ...
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1answer
527 views

Why does SSHFS I/O latency test much faster than local RAID & NFS?

SSHFS tests for server I/O latency using dd returns very surprising results, so much so that I'm worried this might be some problem either with the test method or configuration. Test 1 on local RAID ...
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0answers
386 views

Is it Possible to Configure Receive-Side Scaling on an EC2 Instance Running Windows Server 2012 R2

Currently, I am experiencing some problems on getting a server to run efficiently on an EC2 instance. On my local machine everything runs as expected, but on AWS the servers experience some latency, ...
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0answers
39 views

Find closest (in round-trip time) hosting to a particular serivce behind CDN

I'm using some service which is located behind CloudFlare CDN, and I need to achieve the lowest latency possible in two tasks: receive lots of messages out of WebSocket WAMP subscription with few ...