I just released TopGen, a topology generator for users that want to evaluate internet modeling algorithms which include variants of Barabasi-Albert and FKP. The package also includes TopAnalysis, a graph analysis tool for a few common metrics.
Both tools were initially written in 2005 for my undergraduate thesis. TopGen was later extended to include more models. The release contains the latest versions.
Two weeks ago I had my screen at work upgraded to a 23″ Dell. I figured that I had to find a way to take advantage of the “screen real estate”. After a bit of google searching I ended up choosing xmonad, a tiling window manager. I can see the difference a couple of days later: I have no more tens of windows opened in one taskbar. I’m using workspaces and all open windows are visible in each workspace. I’m using the mouse less than before since windows automatically place themselves on the screen and I can manipulate them with the keyboard
It wasn’t easy getting used to xmonad’s setup configuration. But once you understand what’s happening you realize the possibilities. Here is my configuration.
http://pastebin.com/f6cdbd667
Will explain a bit more when I find the time.
Website for Adball at http://www.adball.com is up and running. Stay tuned for updates.
I just submitted for review in the First ACM SIGCOMM Workshop on Online Social Networks a paper which is about measurements in Facebook with focus on application dissemination .
As I was looking for guitar related applications in Linux I found a game called “Frets on Fire” which seems to be the same as the Guitar Hero game (as seen from the recent Southpark episode). Pretty addictive even with the four initial songs available only. As easy to install as typing:
apt-get install fretsonfire fretsonfire-game fretsonfire-songs-sectoid
In the meantime, while trying to play .mid files I discovered that my soundcard lacks a hardware synthesizer and in Linux you have to install timidity, a virtual synthesizer:
apt-get install timidity freepats
After running the timidity service the command “aplaymidi -l” will show a list of available synthesizer ports. I’m still unable to have kguitar play though (a message about possible experimental importers shows up when I open .mid files).
Captchas are widely used in the Internet to differentiate between humans and computer. The basic idea is to detect automated programs by using a simple challenge that supposedly any human would be able to respond and subsequentially deny service.
Recent research on this area is focusing on exploiting these “human cycles” for meaningful human computation. For example, Luis Von Ahn from CMU has developed games that, when played by humans, label images and objects inside (ESP and Peekaboom).
Recaptcha is another interesting project whose purpose is to help the process of digitizing old books. Every scanned image of a word not recognizable by OCR is used as a Captcha. To confirm the correctness of the human input every time a scanned image of a word is fed into the system it is combined with a known word. If the answer for the known word is correct then a correct answer is assumed for the unknown word too. The main website contains more detailed information. I downloaded their plugin for WordPress and I’m currently using Recaptcha to avoid receiving spam comments. I may have very few posts from third party but I receive hundreds of spam comments every month.
Citeseer contains a list with the estimated impact of publication venues in Computer Science up to 2003. The parameter that determines impact is the average citation rate over all articles in a given year. Self-citations do not count.
Microsoft Libra seems to be more up to date (at this moment until 2006) and with many more interactive features. It supports ranking papers/authors/conferences/journals. The fact that it does not normalize citations over all papers seems to give better rankings.
The last 3-4 weeks I’ve been running Windows XP through Vmware using the free Vmplayer 2.0 package provided by Vmware itself. The exciting thing about this is that Windows are running directly from the physical partition on top of Linux. This may prove useful sometimes for applications/scenarios that definitely need Windows i.e. I still find some MS Office programs such as Visio, again given free from the University , extremely useful.
I followed the excellent guide at http://www.motin.eu/www/mirror/physvmware/ and everything went ok. The re-activation of Windows XP is necessary since the Vmware profile is significantly different from the standard hardware. Fortunately the network was operational so activation was completed online in a matter of seconds. Even though I have 2 processors and 1 GB of RAM, initially processes were running barely ok (mainly I/O and memory thrashing responsible for this). After configuring a couple of options in .vmx file I found myself running Windows within Linux without understanding the difference. Throughout the process it is implied that Vmware tools are already installed.
1st problem fixed – Jerky mouse. For some reason once I logged in and the Vmware service started running the mouse became jerky and sometimes it was jumping. I increased the sample rate up to 200 Hz without seeing a difference. In Vmplayer 1.0.3 stopping the service helped a little but it still did not feel comfortable. In Vmplayer 2.0 that did not help at all. These options fixed the problem.
vmmouse.present = “TRUE”
vmmouse.fileName = “auto detect”
2nd problem fixed – Heavy I/O -As I said before heavy I/O were taking lots of time i.e when an application was executed. Initially I set ide0:0.writeThrough = “TRUE” since writethrough is known to perform better than writeback under heavy load which was constantly observed in my case. That did not help as much (I can’t tell if there was a difference or not). The solution was to disable the creation of a named file (.vmem file).
mainMem.useNamedFile=”FALSE”
That turned out to boost my performance a lot since Vmplayer stored the memory in /tmp which I had set as a dynamic “tmpfs” partition
tmpfs /tmp tmpfs size=1000m,mode=1777 0 0
Therefore depending on my available memory parts of the data were stored directly in RAM. Eventually I set ide0:0.writeThrough = “FALSE” again.
3rd problem – Shared folders – I could see a “Shared Folders” item in the menu but the list of shared folders was disabled. After searching around I found I had to insert the following options in the .vmx file:
sharedFolder.option = “alwaysEnabled”
sharedFolder.maxNum = “1″
sharedFolder0.present = “TRUE”
sharedFolder0.enabled = “TRUE”
sharedFolder0.readAccess = “TRUE”
sharedFolder0.writeAccess = “TRUE”
sharedFolder0.hostPath = “/directorytoshare”
sharedFolder0.guestName = “public”
sharedFolder0.expiration = “never”
isolation.tools.hgfs.disable = “FALSE” is also needed although it can be configured from Vmware icon in the Windows taskbar.
I also find useful to enable copy/paste.
isolation.tools.copy.enable = “TRUE”
isolation.tools.paste.enabled = “TRUE”
Another optimization trick is to unload everything unnecessary i.e I don’t run antivirus neither firewall, I disabled more than 20 services and auto startup applications (msconfig is useful for that). Right now I’ve assigned around 300MB of RAM and when Windows start there are around 150MB free.
Finally even though Vmware runs fine in a Linux window it may be necessary sometimes to run Windows in fullscreen. That may be as easy as changing the resolution in Display or (for my case with a widescreen) inserting a new resolution for the Vmware display driver in the registry.
Vmware has done a fantastic job….I haven’t tried any of the other virtualization tools but what more than this can somebody ask…maybe 3D since I still have problems enabling the mks.enable3d option.
Best wishes for 2007.