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  • Sources of latency in sending-receiving tcp/udp packets in linux

    - by osgx
    Hello What are sources of latency in process of sending/receiving tcp/udp packets in linux 2.6 ? I want to know a latency sources in "ping-pong" latency tests. There are some rather good papers of ethernet latency, but they cover only latency sources in the wire and switch (and rather cursory, only for specific switch). What steps of processing does follow a packet? Papers with deep latency analysis of usual ping (icmp) will be useful too. I rely on community :)

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  • Writing low latency Java

    - by user997112
    Are there any Java-specific techniques (things which wouldnt apply to C++) for writing low latency code, in Java? I often see Java low latency roles and they ask for experience writing low latency Java- which sometimes seems a little bit of an oxymoron. The only think I could think of is experience with JNI, outsourcing I/O calls to native code. Also possibly using the disruptor pattern, but thats not an actual technology. Are there any Java specific tips for writing low latency code? I am aware there is a Real Time Java Spec, but I have been warned real-time is not the same as low latency....

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  • How to remove HDD Low virus

    - by samsudeen
    “HDD Low virus” is a new  fake system optimizer application which started affecting all  the Windows ( XP, vista, Windows 7) based computers world wide starting from Monday. It gets installed to the computers without notice by passing all our antivirus software. The infected computers will suddenly popup a system error  similar to the below screen shot and tries to shut down the computer.   Though the major anti virus companies have not yet release an update for this virus, We can easily remove this virus using the below steps Steps to remove HDD Low virus Press Alt+Ctrl+Delete and go the the Task Manager -> Process and kill the process with name [random number].exe ( e.g 123410.exe) Go to Run -> type msconfig to launch the System Configuration utility. In the Start up Tab un check  all the services with random name (e.g jygkgs.exe) and note folder path of the service in the Command column. Go to that folder path and delete all the exe files with random name manually ( It is recommended to use command prompt to delete the files) Delete all the HDD low files in the below path %Desktop%\HDD Low.lnk %Programs%\HDD Low\Uninstall HDD Low.lnk %Programs%\HDD Low\HDD Low.lnk Open registry using Run-> regedit.exe search for the below key and delete software\Microsoft\Windows\CurrentVersion\Run [random number].exe” Restart the computer Also update your anti virus definition and run a full scan of your computer to remove any affected files. This article titled,How to remove HDD Low virus, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Latency in TCP/IP-over-Ethernet networks

    - by aix
    What resources (books, Web pages etc) would you recommend that: explain the causes of latency in TCP/IP-over-Ethernet networks; mention tools for looking out for things that cause latency (e.g. certain entries in netstat -s); suggest ways to tweak the Linux TCP stack to reduce TCP latency (Nagle, socket buffers etc). The closest I am aware of is this document, but it's rather brief. Alternatively, you're welcome to answer the above questions directly. edit To be clear, the question isn't just about "abnormal" latency, but about latency in general. Additionally, it is specifically about TCP/IP-over-Ethernet and not about other protocols (even if they have better latency characteristics.)

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  • Determining cause of random latency and loading issues

    - by Sherwin Flight
    I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of CSS and JS files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well.

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  • Determining cause of random latency/loading issues

    - by Sherwin Flight
    I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of css/js files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well. Any help or advice is much appreciated.

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  • How to troubleshoot latency between 2 linux hosts

    - by Jimm
    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. How can i know if the latency is due to NIC on host A or B or the switch or the cables? UPDATE: The .23 ms latency is bad for my existing application, which sends messages at very high frequency and i am trying to see if it can be brought down to .1ms

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

    - by SibzTer
    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 customers. The new web application is hosted in amazon aws ec2 environment (N. Virginia region us-east-1b zone). In order to get seamlessly integrate with the legacy application the new web application makes web service calls to retrieve data. We are seeing an unusually high latency time in the order of 5+ seconds for these web service calls. The exact same web service call returns in less than a second on our local PCs (which makes sense given physical proximity to the actual server). The weird part is that we have developers in California who also have the same milliseconds response time. We are testing the web service response using third party tools such as SoapUI, Google Chrome extensions such as Advanced REST Client, Postman REST Client, etc. As if this wasnt weird enough, we have noticed the same low latency from certain other ec2 instances while testing which are in the same region and availability zone as well. If we experienced the high latency consistently from all the ec2 instances I could understand. But there is something else going on. Comparing the various stats and results between the low latency and high latency ec2 servers do not show any significant differences: ping (constant 40ms), tracert, winmtr, etc. We have instances that are in the VPC as well. So I tried both the public and private IP address of the web service host server and that didnt make a difference either for the above results. We need to resolve this latency issue as this is causing the resulting web pages to load very slowly (almost 15+ seconds which is simply unacceptable). The ec2 instances have Windows Server Datacenter 64 bit. Let me know if there is any other infor I can provide to help diagnose this.

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  • Using TCP Acks to measure latency to a server?

    - by Ted Graham
    I am trying to measure latency to a server that I don't control. This is in a colocated environment, so the latency is on the order of 500 us (.5 ms). I understand that Cisco gear frequently deprioritizes ICMP traffic, making ping times unreliable. Is there a way for me to tell if this is the case on the gear I am traversing? Can I use TCP acknowledgements to determine the minimum latency to the remote server? To do this, I would somehow need to force the remote server to send a TCP ack immediately on receiving my data.

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  • Latency in TCP/IP-over-Ethernet networks

    - by aix
    What resources (books, Web pages etc) exist out there that: explain the causes of latency in TCP/IP-over-Ethernet networks; mention tools for looking out for things that cause latency (e.g. certain entries in netstat -s); suggest ways to tweak the Linux TCP stack to reduce TCP latency (Nagle, socket buffers etc). The closest I am aware of is this document, but it's rather brief. Alternatively, you're welcome to answer the above questions directly.

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  • Severe latency only on one machine and only when accessing intranet site

    - by Joe M.
    I have one desktop machine that is having consistently high latency only when trying to load a page from an intranet site. Using the Chrome Developer Tools, the site shows a "Waiting" time of 4-5 seconds each page load. Other machines have <50ms, and the problem machine loads regular internet sites with <1s latency, so the problem is only on one machine and only when accessing the intranet site. This is a small business and all the hosts are on 192.168.0.1/24 I would have suspected a connection issue with the problem machine but normal internet sites are not having latency. Then I would have looked at connection issues with the intranet web server but other machines are not having latency to it. What else can I look at to troubleshoot this?

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  • Low level programming - what's in it for me?

    - by back2dos
    For years I have considered digging into what I consider "low level" languages. For me this means C and assembly. However I had no time for this yet, nor has it EVER been neccessary. Now because I don't see any neccessity arising, I feel like I should either just schedule some point in time when I will study the subject or drop the plan forever. My Position For the past 4 years I have focused on "web technologies", which may change, and I am an application developer, which is unlikely to change. In application development, I think usability is the most important thing. You write applications to be "consumed" by users. The more usable those applications are, the more value you have produced. In order to achieve good usability, I believe the following things are viable Good design: Well-thought-out features accessible through a well-thought-out user interface. Correctness: The best design isn't worth anything, if not implemented correctly. Flexibility: An application A should constantly evolve, so that its users need not switch to a different application B, that has new features, that A could implement. Applications addressing the same problem should not differ in features but in philosophy. Performance: Performance contributes to a good user experience. An application is ideally always responsive and performs its tasks reasonably fast (based on their frequency). The value of performance optimization beyond the point where it is noticeable by the user is questionable. I think low level programming is not going to help me with that, except for performance. But writing a whole app in a low level language for the sake of performance is premature optimization to me. My Question What could low level programming teach me, what other languages wouldn't teach me? Am I missing something, or is it just a skill, that is of very little use for application development? Please understand, that I am not questioning the value of C and assembly. It's just that in my everyday life, I am quite happy that all the intricacies of that world are abstracted away and managed for me (mostly by layers written in C/C++ and assembly themselves). I just don't see any concepts, that could be new to me, only details I would have to stuff my head with. So what's in it for me? My Conclusion Thanks to everyone for their answers. I must say, nobody really surprised me, but at least now I am quite sure I will drop this area of interest until any need for it arises. To my understanding, writing assembly these days for processors as they are in use in today's CPUs is not only unneccesarily complicated, but risks to result in poorer runtime performance than a C counterpart. Optimizing by hand is nearly impossible due to OOE, while you do not get all kinds of optimizations a compiler can do automatically. Also, the code is either portable, because it uses a small subset of available commands, or it is optimized, but then it probably works on one architecture only. Writing C is not nearly as neccessary anymore, as it was in the past. If I were to write an application in C, I would just as much use tested and established libraries and frameworks, that would spare me implementing string copy routines, sorting algorithms and other kind of stuff serving as exercise at university. My own code would execute faster at the cost of type safety. I am neither keen on reeinventing the wheel in the course of normal app development, nor trying to debug by looking at core dumps :D I am currently experimenting with languages and interpreters, so if there is anything I would like to publish, I suppose I'd port a working concept to C, although C++ might just as well do the trick. Again, thanks to everyone for your answers and your insight.

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  • What kinds of low level knowledge matter?

    - by Peter Smith
    I realize that this question is similar to Low level programming - what's in it for me, but the answers didn't really address my question well. Part from just an understanding, how exactly does your low level knowledge translate into faster and better programs? There's the obvious lack of garbage collection, but what else is an advantage? Do you really outperform your optimizing compiler? Do you pack your data structures in as tight as possible and be concerned about alignment? There's extra freedom naturally, but does that really translate into a faster program?

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  • guvcview recording video and audio out of synchronisation in Ubuntu 10.10

    - by SIJAR
    I finally got Guvcview, a great software for Logitech webcam and it does all the stuff that one wants out of it. But I'm not satisfy with the video recording, video and audio out of synchronisation also video seems to be in slow motion. Please help so that I can tweak in and get a good video recording with the webcam. Below is the log of Guvcview ------------------------------------------------------------------------------- guvcview 1.4.1 video_device: /dev/video0 vid_sleep: 0 cap_meth: 1 resolution: 640 x 480 windowsize: 1024 x 715 vert pane: 578 spin behavior: 0 mode: mjpg fps: 1/25 Display Fps: 0 bpp: 0 hwaccel: 1 avi_format: 4 sound: 1 sound Device: 4 sound samp rate: 0 sound Channels: 0 Sound delay: 0 nanosec Sound Format: 85 Pan Step: 2 degrees Tilt Step: 2 degrees Video Filter Flags: 0 image inc: 0 profile(default):/home/sijar/default.gpfl starting portaudio... bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) bt_audio_service_open: connect() failed: Connection refused (111) Cannot connect to server socket err = No such file or directory Cannot connect to server socket jack server is not running or cannot be started language catalog= dir:/usr/share/locale type:UTF-8 lang:en_US.utf8 cat:guvcview.mo mjpg: setting format to 1196444237 capture method = 1 video device: /dev/video0 libv4lconvert: warning more framesizes then I can handle! libv4lconvert: warning more framesizes then I can handle! /dev/video0 - device 1 libv4lconvert: warning more framesizes then I can handle! libv4lconvert: warning more framesizes then I can handle! Init. UVC Camera (046d:0825) (location: usb-0000:00:1d.7-5) { pixelformat = 'YUYV', description = 'YUV 4:2:2 (YUYV)' } { discrete: width = 640, height = 480 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 160, height = 120 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 176, height = 144 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 176 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 320, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 352, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 432, height = 240 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 544, height = 288 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, { discrete: width = 640, height = 360 } Time interval between frame: 1/30, 1/25, 1/20, 1/15, 1/10, 1/5, ... repeats a couple of times ... vid:046d pid:0825 driver:uvcvideo Adding control for Pan (relative) UVCIOC_CTRL_ADD - Error: Operation not permitted checking format: 1196444237 VIDIOC_G_COMP:: Invalid argument compression control not supported fps is set to 1/25 drawing controls control[0]: 0x980900 Brightness, 0:255:1, default 128 control[0]: 0x980901 Contrast, 0:255:1, default 32 control[0]: 0x980902 Saturation, 0:255:1, default 32 control[0]: 0x98090c White Balance Temperature, Auto, 0:1:1, default 1 control[0]: 0x980913 Gain, 0:255:1, default 0 control[0]: 0x980918 Power Line Frequency, 0:2:1, default 2 control[0]: 0x98091a White Balance Temperature, 0:10000:10, default 4000 control[0]: 0x98091b Sharpness, 0:255:1, default 24 control[0]: 0x98091c Backlight Compensation, 0:1:1, default 1 control[0]: 0x9a0901 Exposure, Auto, 0:3:1, default 3 control[0]: 0x9a0902 Exposure (Absolute), 1:10000:1, default 166 control[0]: 0x9a0903 Exposure, Auto Priority, 0:1:1, default 0 resolutions of format(2) = 19 frame rates of 1º resolution=6 Def. Res: 0 numb. fps:6 --------------------------------------- device #0 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 (hw:0,0) Host API = ALSA Max inputs = 2, Max outputs = 2 Def. low input latency = 0.012 Def. low output latency = 0.012 Def. high input latency = 0.046 Def. high output latency = 0.046 Def. sample rate = 44100.00 --------------------------------------- device #1 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - MIC ADC (hw:0,1) Host API = ALSA Max inputs = 2, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #2 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - MIC2 ADC (hw:0,2) Host API = ALSA Max inputs = 2, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #3 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - ADC2 (hw:0,3) Host API = ALSA Max inputs = 2, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #4 Name = Intel 82801DB-ICH4: Intel 82801DB-ICH4 - IEC958 (hw:0,4) Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.011 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #5 Name = USB Device 0x46d:0x825: USB Audio (hw:1,0) Host API = ALSA Max inputs = 1, Max outputs = 0 Def. low input latency = 0.011 Def. low output latency = -1.000 Def. high input latency = 0.043 Def. high output latency = -1.000 Def. sample rate = 48000.00 --------------------------------------- device #6 Name = front Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.012 Def. high input latency = -1.000 Def. high output latency = 0.046 Def. sample rate = 44100.00 --------------------------------------- device #7 Name = iec958 Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.011 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #8 Name = spdif Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.011 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #9 Name = pulse Host API = ALSA Max inputs = 32, Max outputs = 32 Def. low input latency = 0.012 Def. low output latency = 0.012 Def. high input latency = 0.046 Def. high output latency = 0.046 Def. sample rate = 44100.00 --------------------------------------- device #10 Name = dmix Host API = ALSA Max inputs = 0, Max outputs = 2 Def. low input latency = -1.000 Def. low output latency = 0.043 Def. high input latency = -1.000 Def. high output latency = 0.043 Def. sample rate = 48000.00 --------------------------------------- device #11 [ Default Input, Default Output ] Name = default Host API = ALSA Max inputs = 32, Max outputs = 32 Def. low input latency = 0.012 Def. low output latency = 0.012 Def. high input latency = 0.046 Def. high output latency = 0.046 Def. sample rate = 44100.00 ---------------------------------------------- SampleRate:0 Channels:0 Video driver: x11 A window manager is available VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_CTRL for user class controls control(0x0098091a) "White Balance Temperature" failed to set (error -1) VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_EXT_CTRLS on single controls for class: 0x009a0000 control(0x009a0902) "Exposure (Absolute)" failed to set (error -1) VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_CTRL for user class controls control(0x0098091a) "White Balance Temperature" failed to set (error -1) VIDIOC_S_EXT_CTRLS for multiple controls failed (error -1) using VIDIOC_S_EXT_CTRLS on single controls for class: 0x009a0000 control(0x009a0902) "Exposure (Absolute)" failed to set (error -1) Cap Video toggled: 1 (/home/sijar/Videos/Webcam) 25371756K bytes free on a total of 39908968K (used: 36 %) treshold=51200K using audio codec: 0x0055 Audio frame size is 1152 samples for selected codec IO thread started...OK [libx264 @ 0x8cbd8b0]using cpu capabilities: MMX2 SSE2 Cache64 [libx264 @ 0x8cbd8b0]profile Baseline, level 3.0 [libx264 @ 0x8cbd8b0]non-strictly-monotonic PTS shift sound by -9 ms shift sound by -9 ms shift sound by -9 ms AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... AUDIO: droping audio data (/home/sijar/Videos/Webcam) 25371748K bytes free on a total of 39908968K (used: 36 %) treshold=51200K AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... Cap Video toggled: 0 Shuting Down IO Thread AUDIO: droping audio data stop= 4426644744000 start=4416533023000 VIDEO: 146 frames in 10111.000000 ms = 14.439719 fps Stoping audio stream Closing audio stream... close avi Last message repeated 145 times [libx264 @ 0x8cbd8b0]frame I:2 Avg QP:14.10 size: 24492 [libx264 @ 0x8cbd8b0]frame P:103 Avg QP:16.06 size: 20715 [libx264 @ 0x8cbd8b0]mb I I16..4: 48.4% 0.0% 51.6% [libx264 @ 0x8cbd8b0]mb P I16..4: 57.5% 0.0% 0.0% P16..4: 40.2% 0.0% 0.0% 0.0% 0.0% skip: 2.3% [libx264 @ 0x8cbd8b0]final ratefactor: 62.05 [libx264 @ 0x8cbd8b0]coded y,uvDC,uvAC intra: 79.7% 92.2% 68.4% inter: 62.4% 87.5% 48.0% [libx264 @ 0x8cbd8b0]i16 v,h,dc,p: 23% 17% 41% 19% [libx264 @ 0x8cbd8b0]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 30% 24% 26% 2% 5% 3% 3% 3% 4% [libx264 @ 0x8cbd8b0]i8c dc,h,v,p: 53% 20% 23% 4% [libx264 @ 0x8cbd8b0]ref P L0: 63.0% 37.0% [libx264 @ 0x8cbd8b0]kb/s:-0.00 total frames encoded: 0 total audio frames encoded: 0 IO thread finished...OK IO Thread finished enabling controls Cap Video toggled: 1 (/home/sijar/Videos/Webcam) 25379744K bytes free on a total of 39908968K (used: 36 %) treshold=51200K using audio codec: 0x0055 Audio frame size is 1152 samples for selected codec IO thread started...OK [libx264 @ 0x8cfba20]using cpu capabilities: MMX2 SSE2 Cache64 [libx264 @ 0x8cfba20]profile Baseline, level 3.0 [libx264 @ 0x8cfba20]non-strictly-monotonic PTS shift sound by -236 ms shift sound by -236 ms shift sound by -236 ms (/home/sijar/Videos/Webcam) 25377044K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25373408K bytes free on a total of 39908968K (used: 36 %) treshold=51200K AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... (/home/sijar/Videos/Webcam) 25370696K bytes free on a total of 39908968K (used: 36 %) treshold=51200K AUDIO: droping audio data AUDIO: droping audio data AUDIO: droping audio data ... repeats a couple of times ... (/home/sijar/Videos/Webcam) 25367680K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25364052K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25360312K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25356628K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25352908K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25349316K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25345552K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25341828K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25338092K bytes free on a total of 39908968K (used: 36 %) treshold=51200K (/home/sijar/Videos/Webcam) 25334412K bytes free on a total of 39908968K (used: 36 %) treshold=51200K Cap Video toggled: 0 Shuting Down IO Thread stop= 4708817235000 start=4578624714000 VIDEO: 1604 frames in 130192.000000 ms = 12.320265 fps Stoping audio stream Closing audio stream... close avi Last message repeated 1603 times [libx264 @ 0x8cfba20]frame I:16 Avg QP:14.78 size: 42627 [libx264 @ 0x8cfba20]frame P:1547 Avg QP:16.44 size: 28599 [libx264 @ 0x8cfba20]mb I I16..4: 21.6% 0.0% 78.4% [libx264 @ 0x8cfba20]mb P I16..4: 28.1% 0.0% 0.0% P16..4: 70.5% 0.0% 0.0% 0.0% 0.0% skip: 1.4% [libx264 @ 0x8cfba20]final ratefactor: 88.17 [libx264 @ 0x8cfba20]coded y,uvDC,uvAC intra: 74.4% 95.8% 83.2% inter: 75.2% 94.6% 69.2% [libx264 @ 0x8cfba20]i16 v,h,dc,p: 27% 17% 40% 16% [libx264 @ 0x8cfba20]i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 25% 21% 3% 6% 4% 5% 4% 7% [libx264 @ 0x8cfba20]i8c dc,h,v,p: 61% 18% 18% 4% [libx264 @ 0x8cfba20]ref P L0: 64.0% 36.0% [libx264 @ 0x8cfba20]kb/s:-0.00 total frames encoded: 0 total audio frames encoded: 0 IO thread finished...OK IO Thread finished enabling controls Shuting Down Thread Thread terminated... cleaning Thread allocations: 100% SDL Quit Video Thread finished write /home/sijar/.guvcviewrc OK free audio mutex closed v4l2 strutures free controls free controls - vidState cleaned allocations - 100% Closing portaudio ...OK Closing GTK... OK

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  • CentOS Latency High Troubleshooting

    - by Sarah Weinberger
    I have two CentOS servers connected via a 10 Gb fiber optic cable with a network emulator connected between them. All three units sit on a desk in the lab. There is also a regular 1 Gbit Ethernet cable connected to each of the machines, which provide internet connectivity. When I set the latency to something roughly below 30 ms, all is fine. When the latency gets to 70ms and above, and definitely 130ms, the network layer suspends. For instance, if I set the latency (delay) to 70ms, then launching TeamViewer (or any other application that uses network connectivity) never happens or does not work. There is no timeout message, simply no response. I have to lower to latency back down to zero to see any response and have the box start working. What is the problem and how would I go about fixing it? It seems to me some sort of setting in Linux causes one of the CentOS networking drivers to sit in an infinite loop or something. eth0 is the connection to the internet, all settings are default eth2 is the 10 Gbit fiber optic connection to the other computer with the MTU set to 9600 with all other parameters at default values.

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  • Simulating network latency for localhost connection on Windows 7

    - by nitro2k01
    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 trial and error. While it generally works, I can't seem to get it to filter localhost traffic. Even after adding a rule from any to any which affects external traffic, this makes no difference for local connections. I would appreciate if anyone knows how to simulate local latency using dummynet or a different tool. The tool should be able to simulate latency generically in IP packets, (TCP and UDP) and not be protocol specific.

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  • latency, regular alternations. Pfsense, network

    - by Tillebeck
    Any idea why grapgh is a shown? It i two pfsense boxes and I have not looked into where they ping to and if it is related to the server they ping. Trafic graphs are following a normal 24 hour cycle and not related to either of the latency graphs Img1: High frequent ulteration in latency. Just started a few days back. Peaks are not perfectly regular but varies from 40min to 1hour Img2: This is a different router on another internet connection. Most of our routers shown this kind of latency graphs - so for our setup it is "normal". Please note that second graph is for a whole week and not just some hours

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  • one two-directed tcp socket OR two one-directed? (linux, high volume, low latency)

    - by osgx
    Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE network benchmark - measure latency and bandwidth for sizes from 2^1 up to 2^13 bytes, each size sent and received 3 times at least (in teal task the number of sends is greater. both processes will be sending and receiving, like ping-pong maybe). The benefit of 2 uni-directed connections come from linux: http://lxr.linux.no/linux+v2.6.18/net/ipv4/tcp_input.c#L3847 3847/* 3848 * TCP receive function for the ESTABLISHED state. 3849 * 3850 * It is split into a fast path and a slow path. The fast path is 3851 * disabled when: ... 3859 * - Data is sent in both directions. Fast path only supports pure senders 3860 * or pure receivers (this means either the sequence number or the ack 3861 * value must stay constant) ... 3863 * 3864 * When these conditions are not satisfied it drops into a standard 3865 * receive procedure patterned after RFC793 to handle all cases. 3866 * The first three cases are guaranteed by proper pred_flags setting, 3867 * the rest is checked inline. Fast processing is turned on in 3868 * tcp_data_queue when everything is OK. All other conditions for disabling fast path is false. And only not-unidirected socket stops kernel from fastpath in receive

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  • one two-directed tcp socket of two one-directed? (linux, high volume, low latency)

    - by osgx
    Hello I need to send (interchange) a high volume of data periodically with the lowest possible latency between 2 machines. The network is rather fast (e.g. 1Gbit or even 2G+). Os is linux. Is it be faster with using 1 tcp socket (for send and recv) or with using 2 uni-directed tcp sockets? The test for this task is very like NetPIPE network benchmark - measure latency and bandwidth for sizes from 2^1 up to 2^13 bytes, each size sent and received 3 times at least (in teal task the number of sends is greater. both processes will be sending and receiving, like ping-pong maybe). The benefit of 2 uni-directed connections come from linux: http://lxr.linux.no/linux+v2.6.18/net/ipv4/tcp_input.c#L3847 3847/* 3848 * TCP receive function for the ESTABLISHED state. 3849 * 3850 * It is split into a fast path and a slow path. The fast path is 3851 * disabled when: ... 3859 * - Data is sent in both directions. Fast path only supports pure senders 3860 * or pure receivers (this means either the sequence number or the ack 3861 * value must stay constant) ... 3863 * 3864 * When these conditions are not satisfied it drops into a standard 3865 * receive procedure patterned after RFC793 to handle all cases. 3866 * The first three cases are guaranteed by proper pred_flags setting, 3867 * the rest is checked inline. Fast processing is turned on in 3868 * tcp_data_queue when everything is OK. All other conditions for disabling fast path is false. And only not-unidirected socket stops kernel from fastpath in receive

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  • What are different ways to reduce latency between a server and a web application? [closed]

    - by jjoensuu
    this is a question about a web application that provides SOAP web services. For the sake of this question, this web app is hosted on a server SERVER B which is located in California. We have an automated, scheduled, process running on a server SERVER A, located in New York. This scheduled process is supposed to send SOAP messages to SERVER B every so often, but this process typically dies soon after starting. We have now been told by the vendor that reason why the process dies is because of the latency between SERVER A and SERVER B. The data traffic is routed through many diffent public networks. There is no dedicated line between SERVER A and SERVER B. As a result I have been asked to look into ways to reduce the latency between SERVER A and SERVER B. So I wanted to ask, what are the different ways to reduce latency in a situation like this? For example, would it help to switch from HTTPS to some other secure protocol? (the thought here is that perhaps some other alternative would require fewer handshakes than HTTPS). Or would a VPN help? If a VPN would reduce the latency, how would it do that? NOTE: I am not looking for an explicit answer that would work in my specific situation. I am more like looking just for a simple list of what technologies could be used for this. I will still have to evaluate the technologies and discuss them internally with others, so the list would just be a starting point. Here I am assuming that there exists very few ways to reduce latency between two servers that communicate across public networks using HTTPS. Feel free to correct me if this assumption is wrong and please ask if there is a need for specific information. NOTE 2: A list of technologies is a specific answer to the question I stated in the title. NOTE 3: Its rather dumb to close this question when it is after all about me looking for information and furthermore this information can clearly be useful for others. Anyway luckily there are other sites where I can ask around. StackExchange seems to attached to their own philosophical principles. Many thanks

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  • finding the best network latency between two countries

    - by Yoav Aner
    I know there are many tools to test for bandwidth and latency, but they all rely on having at least one host from which you can run those tests. I wonder whether there's an online source or some other way to guestimate the latency or speed between two countries (in general). For example, would a customer in Japan get lower latency if the server is located in Singapore or Australia? Is a user in India likely to get higher download speed from a server in the UK or in the US? Are there any online resources or some clever ways to answer those questions with a reasonable degree of accuracy? [UPDATE]: Thanks for the great suggestions from Raffael Luthiger. I didn't know about those looking glass servers. The submarine cable maps were also really cool to discover (Thanks to Jesper Mortensen). Also seems really wise if I could ask those network professional in the area for their experience, but obviously I don't have access to those. At least some of them are on SF :) However, I'm still a little unsure how to combine those resources to give me some measurements. This is the information I have: Two countries (A,B). I do have IP addresses of customers in country A (I can obtain those from the web server log files for example). Presumably I can find some looking glass servers in country B and run a trace to those IPs. What's the best measurements to use? Are there any scripts that help automate at least some of this process?

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  • wireless router - configuring for low-latency, high traffic environment

    - by Mark C
    Hey all, I have a few questions about configuring a router to achieve low-latency, high speed throughput on a local area network that is not connected to the internet. I've read up on some stuff, but thought I would solicit some opinions here on what I've found and what I want to know.... Turn off SSID broadcast - it produces extraneous packets that all clients receive and reply (?) to. Not a huge deal, but it may help a bit. Mixed-mode off - I should attempt to have all devices using the same standard (e.g. 802.11n) and turn mixed-mode off. Any thoughts on security? Does having WEP or any of the WPA variants actually increase latency? Nothing super secure is going over this LAN so if turning security off made things better, that'd be cool. Any other thoughts or things to focus on to create the low latency environment I'm trying to go for would be great. Links to webpages and papers are also cool. I'm open to go through a bunch of stuff. Thanks in advance!

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  • SQL Server replication - Log Reader Agent Read Latency Issue, Please help

    - by envykok
    Hi all, I am facing one transactional replication delay issue on log reader agent. The log reader output is : ********* STATISTICS SINCE AGENT STARTED ************** 02-28-2011 20:12:08 Execution time (ms): 304141 Work time (ms): 304016 Distribute Repl Cmds Time(ms): 303764 Fetch time(ms): 300813 Repldone time(ms): 1826 Write time(ms): 5319 Num Trans: 15500 Num Trans/Sec: 50.984159 Num Cmds: 191639 Num Cmds/Sec: 630.358271 It seems Log Reader Reader-Thread Latency, and I also run 'sp_replcounters' and see more than 20,000 sec replication latency and keep on increasing. I used SQL profiler to monitor sp_replcmds and found sp_replcmds execution time was 11 sec to 15 sec Is it there any way to optimize to make Log Reader read faster from transaction log??? Other information: SQL Server 2008 (SP2) Standard 64 bit

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  • Ultra Low Latency Linux Distribution or Kernel

    - by Zanlor
    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 ethernet, we're looking into things like infiniband RDMA and Voltaire VMA I've googled around, and have only been able to find tidbtits of kernel patches, command line options and hardware suggestions. I'm looking for a complete solution, specially built kernel, kernel bypass features, essentially all the goodies rolled up into one package - does such a thing even exist? I ask as a lot of this stuff seems to be a black art, people keep secret what they know works etc.

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  • Ultra Low Latency Linux Distribution or Kernel

    - by Zanler
    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 ethernet, we're looking into things like infiniband RDMA and Voltaire VMA I've googled around, and have only been able to find tidbtits of kernel patches, command line options and hardware suggestions. I'm looking for a complete solution, specially built kernel, kernel bypass features, essentially all the goodies rolled up into one package - does such a thing even exist? I ask as a lot of this stuff seems to be a black art, people keep secret what they know works etc.

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