Latency is the time difference between the start of an event and the time that the effects become noticeable.

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17
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3answers
8k views

What does “Windows is not a real-time operating system” mean?

I came across an application called LatencyMon, that apparently does latency monitoring. I have always understood that the more of a load you put on the processor, the less responsive, or more ...
15
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2answers
4k views

What do the memory timings and RAM mean?

On every piece of RAM you'll see the timings like: "2-2-2-5". What is this all about? What should I buy?
15
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4answers
4k views

Negative ping time?

This is the first time I've seen this and I'm not sure what it means; 64 bytes from 74.125.93.99: icmp_seq=6233 ttl=53 time=545.493 ms 64 bytes from 74.125.93.99: icmp_seq=6234 ttl=53 time=776.093 ...
14
votes
6answers
3k views

Does increasing upload or download speed reduce ping?

I have a 5 MB/s connection, but I always notice high ping when playing online games. When the network is stable (i.e. when pingtest.com reports the connection as 5 MB/s), the ping stays at 50 ms, but ...
8
votes
1answer
2k views

How does RAM frequency and latency differ? How does it affect performance?

I have a question regarding two specifications of RAM memory, the amount of Mhz and the latency timings (example: 9-9-9-24). Which one of the two is most important for system performance and why? ...
8
votes
3answers
727 views

Xeon vs overclocked i7 Extreme for lowest latency

I am aware that the differences between high-end i7 and Xeon are: compatibility with dual socket motherboards, total L2/L3 cache size. overclocking capability. extra cores - Haswell ...
7
votes
1answer
1k views

I sometimes get lag spikes causing ping times of 200 ms; might using different (e.g. Google's) DNS servers be better?

I live in the UK and I am a heavy gamer and I get lag spikes that take my ping to 200ms. Will using a third-party DNS Service, for example the one provided by Google, rather than those provided by my ...
7
votes
3answers
5k views

Latency of CPU instructions on x86 and x64 processors

I'm looking for some table or something similar that could help me to calculate efficiency of assembly code. As I know bit shifting takes 1 CPU clock, but I really looking how much takes addition ...
7
votes
3answers
5k views

Debugging Linux I/O latency

I'm having some I/O problems on a couple of Linux systems that I administer. They manifest in that processes often block for up to several seconds in such simple syscalls as open(), unlink() or ...
7
votes
3answers
2k views

Fixing bufferbloat in home network

In our home network, with continuous network IO happening latencies get ridiculous. It's fine with light loads but quickly becomes unusable if I'm, say, rsyncing a large number of small files, --other ...
7
votes
4answers
742 views

Does RAM timings with n-n-n-3n value perform better than anything else?

I want to ask something: Does RAM timings with n-n-n-3n (i.e. 8-8-8-24, 9-9-9-27, etc) perform better or is optimized more than the other who doesn't (i.e. 7-8-7-21, 9-9-9-24, etc)?
6
votes
3answers
7k views

Network latency measurement (Linux)

I'd like to measure network latency for SNMP GET request. There is a free command line tool time which can be used to find timing statistics for various commands. For example it can be used with ...
6
votes
1answer
14k views

VLC Caching levels

When I open the Preferences of VLC and go to Input & Codecs, I have a setting called Default Caching Level. I can choose between Cusom Lowest latency Low latency Normal High latency Higher ...
6
votes
2answers
3k views

Alternating low and high ping times on ADSL line

I have an ADSL connection at home. Pings times are usually acceptable right after rebooting the modem, between 15 and 60ms to google.com. A few minutes later they go up to 900ms or even higher up to 3 ...
5
votes
2answers
6k views

Calculating hard disk block model reading time

My professor posted a slide on how to calculate the data retrieval from hard disk using the block model. The specs were: 7200 RPM 5ms SEEK 80MB/s TRANSFER RATE BLOCK MODEL : Block size 4KB I ...
5
votes
1answer
1k views

Should the use of USB extension cables raise a concern about latency/performance?

Is there any need to be concerned about latency in transmission of any level of data/signal for USB devices when a USB extension cable is being used? For this example lets say it's a 50cm cable (~1.6 ...
5
votes
3answers
3k views

Roommate lagging internet connection by watching videos from Chinese website. Can QoS fix issue?

My roommate is an international student from China and likes to watch Chinese TV shows online using a website based in that region (we're on the U.S. East Coast). But it causes our network's latency ...
5
votes
2answers
1k views

High packet loss - all hops show red

I've run Ping Plotter and here are the results with high packet loss on all hops (around 12%). I find hard to believe Google's routers are faulty, is it my network card to blame? Click the ...
4
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2answers
2k views

How to solve extreme DPC latency peaks (240.000µs)

Once every few minutes I get a sudden peak of DPS latency that causes the system to "freeze" for a fraction of a second (240.000µs = 240ms). The freeze is not only audio, also video, input devices, ...
4
votes
1answer
3k views

How to reduce latency with openssh?

I'm ssh-ing to a server several thousands kilometers away, and every keystroke takes 500-800ms, so it is getting annoying. Is it possible to have my ssh client cache each line I type locally and ...
4
votes
3answers
3k views

Live Screencast under Linux

I was having some difficulty with running a Live Screencast under Linux. I've found jtvlc and tried using that, but whenever I use it the stream comes out either blank or lagged with extremely high ...
4
votes
2answers
748 views

SSH and Latent Connections (e.g., satellite connections)

Most of the week I live in the city where I have a typical broadband connection, but most weekends I'm out of town and only have access to a satellite connection. Trying to work over SSH on a ...
4
votes
1answer
1k views

How to ssh in the face of huge (25 second) latency?

I need to create an ssh connection between two Linux machines running Centos v5 but the latency could be as high as 25 seconds. I find that if I test something approaching this configuration ...
4
votes
2answers
644 views

Very low latency streaming

I'm looking to stream a live lecture into an overflow lecture theater. I'm planning to stream HD content along with audio from a powerful server with nVidia GeForce GPUs connected to the client via a ...
3
votes
3answers
2k views

Memory, more frequency, or more capacity?

My question my be simple, but I haven't been able to find an answer myself yet. If you had the choice of getting either 24 GB of ram at 1333 MHz, or 12 GB @ 1600 MHz, which would you choose? I know ...
3
votes
2answers
2k views

Why do Jumbo Frames hurt latency?

Recently I've been reading about jumbo frames and I got confused in a few places. As far as I understand there is a lower bound on the Ethernet frame size between 'store and forward' points (layer 2 ...
3
votes
1answer
1k views

Increasing value of sched_latency_ns and sched_min_granularity_ns

Why do I get an error message when I try to increase the values of these two parameters: #cat /proc/sys/kernel/sched_latency_ns 1000000000 #echo 2000000000 > /proc/sys/kernel/sched_latency_ns ...
3
votes
6answers
3k views

(linux) tool to monitor “quality” of tcp connection?

I am looking for a tool to monitor the quality of a TCP connection. I am trying to describe what I mean: It should be a tool with a client and a server part. The client sends, say, 1kB of data per ...
3
votes
1answer
583 views

Windows 7 Lagging with multiple disks

I have an EVGA SR2 build with two Intel Xeon X5680, 48GB ram OCZ Reaper HPC Series at 1600 MHz running on Windows 7 x64 Proffesional. My bootable hard drive is an OCZ Vertex II 120GB and I have an ...
3
votes
2answers
862 views

How to increase transfer speed on fat long pipe?

I have a log pipe between two facilities (gigiabit circuit with RTT latency of 17ms). When doing system-to-system file transfer (file sharing, rsync, ftp, sftp) I'm hitting maximum speed of approx 30 ...
3
votes
3answers
459 views

Windows 7 Network Mystery

I'm having serious connectivity issues in Windows 7 and I'm out of diagnostic ideas. Here's way too much detail: Machine is about 6 months old, haven't had a problem up until yesterday. Internet ...
3
votes
1answer
328 views

Experiencing lockups due remote system Hard drive being shut off

Whenever I open a homegroup folder on another computer on my network, and the remote harddrive has to spin up, windows explorer seems to lock up until the remote request completes. This affects ...
2
votes
2answers
5k views

What's the minimum network latency for a 1000 km connection using optic fibers?

I know most of the network latency for short distances is due to router processing times. But for longer distances the speed of light also counts. And it's different from the speed the light in the ...
2
votes
2answers
146 views

Is there a way to use a service to lower your latency?

There is this service wtfast that claims it can lower your ping in some games. Is this true? How it works?
2
votes
2answers
2k views

Simulating network latency for localhost connection on Windows 7

I need to simulate network latency to a program running on the local computer, connecting to a local service. Thus far I have tried dummynet (a windows build of ipfw) which I got working after some ...
2
votes
1answer
1k views

Low latency keyboards - are they for real?

Having just seen some commercial or other I just realized there could be such a thing as a high-latency keybard - as compared to a low-latency keyboard. If so then maybe a low-latency one could be yet ...
2
votes
2answers
275 views

understanding traceroute output to diagnose an issue with Verizon FIOS

Tech support has tried, and failed, to repeatedly fix anything, which makes me think the issues are deep within the Verizon network. But I'd like a quick sanity check, since I'm not very experienced ...
2
votes
3answers
7k views

Very high latencies with WiFi

We bought a new WiFi router / ADSL modem at home (Asus DSL-N55U-B) and the wifi connection occasionally has very high latencies (up to 20 seconds, versus most common 25 miliseconds when pinging google ...
2
votes
1answer
196 views

Microsoft Word 2003 - Debug loading times?

Loading new and most local documents is fast as hell, but a few specific documents can take up to 10 minutes to load, which is not acceptable. I know that these documents have macros enabled and ...
2
votes
1answer
483 views

What is the best way to connect two Macs to minimize network latency?

What is the best way to connect two Mac Minis, one running Lion and the other one running Snow Leopard, to minimize latency for sharing screen? Right now they are connected through a wireless network ...
2
votes
1answer
119 views

Powerful monitoring applications for Windows

I have been using the Windows 7 Resource Monitor lately which has proven very powerful. One can see what disk latency any process produces and effectively disable it if not required. For example, I ...
2
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0answers
275 views

Stuttering/Latencies when LAN/Ethernet Driver active

I experience heavy video/audio stuttering when playing a video or general latencies when downloading a file when connected via LAN/Ethernet NOT when connected via WLAN/Wifi. According to my ...
2
votes
1answer
1k views

Improve and Reduce Latency in DD-WRT with QoS

I was tasked with making a home network today and after installing DD-WRT in one of the routers, I ran some diagnosis and the games became a problem. There is usually one or two people using Internet ...
2
votes
0answers
550 views

How to reduce latency on FFmpeg video streaming?

On a video streaming application between Linux server (FFmpeg) and Windows client (VLC player), there is a noticeable latency of about 10 seconds. FFmpeg command: ffmpeg -re -f v4l2 -i /dev/video0 ...
2
votes
0answers
7k views

How to fight network latency and jitter issues on Wifi?

I'm having problems with my Wifi connection. I did a test on PingTest.net with the following results: Packet Loss: 0% Ping: 103ms Jitter: 29ms Same test but from another machine on the network ...
2
votes
2answers
268 views

Ping spikes in Windows 7

This is what my average latency looks like. Request timed out. Reply from 74.125.224.198: bytes=32 time=470ms TTL=53 Reply from 74.125.224.198: bytes=32 time=31ms TTL=53 Reply from 74.125.224.198: ...
2
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0answers
103 views

How to benchmark hard disk? [duplicate]

I am trying to benchmark my hard disk and find the throughput in Mb/s and latency in milliseconds. This is my code: public class OneMB implements Timer { public static void main(String a[]) throws ...
1
vote
3answers
121 views

Why would latency suddenly go up when crossing networks?

I'm looking at the latency from my machine to a world of warcraft server. Every hop while I am in Comcast's network is sub 15ms. Then it hits ATT and goes to 60-70MS for the rest. Why would it ...
1
vote
5answers
4k views

How To Improve VOIP Sound Quality

PFSense 1.2.2 Cisco IP Phone 7940 (SIP Firmware - G711ulaw) ADSL 6000/768 Asterisk Hi Guys, I'm having trouble maintaining stable outbound VOIP call quality from my home office. Inbound call ...
1
vote
2answers
232 views

When buying RAM on a budget, do I choose higher capacity or lower latency?

I would like to know how much of a difference is attainable by using RAM with lower timings and whether that difference is justified by the price. Phrased differently, will lower latency RAM also have ...