Questions tagged [latency]

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

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Strongswan high latency on LTE

Allow me to ask for help to solve the following problem with latency. I have a network which is on one side the Strongswan server and on the opposite side are terminals connected through DSL, cable or ...
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1answer
20 views

Determining on which machine a packet/update arrived first

I have two separate AWS Virtual Machines set up within a region (different availability zones) both are connected via WebSocket (in Python) to a different load balancer (Cloudfront) of the same host ...
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VNET Peering Latency

I’m running a mission critical global three-tier-application (App, IIS & SQL Virtual machines) on same region (Central US), right now, some of the European users are suffering poor performance. I’...
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1answer
138 views

Using tc to decrease bandwidth to a specific destination address

I am trying to find the shortest path between two hosts H1 and H2 using Dijkstra code. Setting a condition in one of the switches on that path. the condition is: if the packet sending to H2 then ...
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2answers
26 views

If my database has to stay in one region, is there much point distributing my API across several?

We currently have an API and database in Australia, and are attempting to reduce latency in other countries. Coming to grips with the CAP theorem for synchronized databases is probably a little out-...
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1answer
65 views

App Engine high latency

Hi we have an static web page using Smarty, we want to migrate it from our private web server on Compute Engine to App Engine. We did made the migration but on App Engine we got a latency of 3 sec to ...
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42 views

Delay on NFS mounts

My setup: 3 machines, 2 client, 1 server. The server is redhat 7.6, the clients are ubuntu server 18.04.2. The mount is a few dozen TB, the files placed on the clients are a few 100Gigs each. The ...
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How to Achieve Multi-Region API Server without Database Conflict

Currently I'm building a webapp that has an intended global audience, no specific region. To reduce latency I've gone through the usual steps of having a Redis in-memory cache, local caching in ...
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59 views

Azure App Service / Postgresql high latency

We have an very simple Azure App Service application using Django (Python) running in West EU Region. The Service Plan for this Service is P1v2 (production plan). The Postgresql is configure with ...
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100 views

Hyper-V inconsistent/high latency between two VMs on the same vSwitch

This is a clean installation of Windows 10 1903 with Hyper-V, though I've experienced this in previous versions of Windows 10. Add a private vSwitch (so, not tied to any physical network adapter). ...
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1answer
32 views

What is the fastest posible way to comunicate to a server on Amazon EC2?

I need to communicate via WebSockes and normal HTTP. I am trying to save some microseconds. I have already done: I got an instance at the same Amazon EC2 zone. The ping is 1 millisecond. I have ...
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42 views

Extended TTFB/Server Wait Time on AWS/ElasticBeanstalk Deployment

I've recently taken over front-end dev for a company but there was some server management stuff slipped in there, so I'm trying to get as up to speed as possible. Site Load Waterfall Screenshot Some ...
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Latency jumps in first, middle and last mile of path

I work for SD-WAN company providing an all in one solution edge router(Like FORTINET but not FORTINET). We have one customer in particular that has such a hard time with our services i.e. gift card ...
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67 views

NPing gives significantly less time on `TCP Connect` than `TCP`

I'm using NPing (NMap's pinging tool) to measure latency on specific servers that may not respond to ICMP. Also, servers do not usually run HTTP(S) and I only check latency on a specific TCP port ...
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38 views

Baffling “indefinite load” issue experienced by users

I was hoping that perhaps one of you guys have an idea about what is happening. For your convenience, I summarized the issue I have been experiencing below including everything we have tried so far. ...
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Do web farms help to reduce latency caused by physical distance?

There are many causes of high latency but I'm only interested with the one caused by physical distance between client and server. Web/server farms utilize multiple servers coupled with load balancers ...
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1answer
44 views

One machine's network usage can increase latency for everyone sharing the same ethernet switch

I'm managing an office network of about 20 computers, which all share a common ethernet switch (unmanaged), which is then connected to the ISP's cable modem/router combo. Every now and then someone ...
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560 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
302 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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272 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
182 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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137 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
42 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 ...
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1answer
250 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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2answers
124 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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2answers
562 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, ...
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132 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
47 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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564 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
706 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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1answer
31 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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1answer
127 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
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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
8k 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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92 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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136 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 ...
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1answer
1k 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
17k 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 ...
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1answer
365 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
185 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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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 ...
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1answer
251 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 ...
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1answer
447 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 ...
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1answer
254 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
50 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 ...
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2answers
310 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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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
82 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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4answers
7k 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 ...
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1answer
135 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 ...