Teaching CS498 at UIUC

I have been appointed as Adjunct Assistant Professor in Computer Science at UIUC since last year. My first service to the CS department is teaching the lecture CS498 “Hot Topics in HPC: Networks and Fault Tolerance” together with Franck Cappello this semester. It is the first class that I teach in the US academic system and it is a bit different from what we used to do in Germany. Classes are generally smaller (I have around 20-25 students, some of which do not take credit) which enables a more interactive teaching style. In my networking part, I start with focusing on the theoretical foundations and models for communication and then show practical examples for each of them and how the knowledge can help practical setting. I think it’s most important to understand the basics (this is also harder to learn and understand from textbooks than the technical details) before diving into practical networks. Teaching this class has been a lot of fun so far even though the preparations are really weekend-time consuming. I really enjoy the interactions with the students during class.


I’m teaching the class every Wed and Fri 9:30-10:45am in Siebel 1103. If anyone is interested in the content, check out the class webpage at http://www.unixer.de/CS498/ .

SC10 Best Paper

Yes, we received the SC10 Best Paper Award for our paper “Characterizing the Influence of System Noise on Large-Scale Applications by Simulation”. Congratulations also to Timo and Andrew! SC10 is the premier international venue for HPC research and development. Only 50 of the 253 submitted papers have been accepted at SC10 and it was very nice to hear that our paper was one of the best paper nominees (each track nominated a best paper), but I didn’t expect that we would be best of all the nominees! The final decision was made after the presentations. My talk was in a way too small room which was completely packed (people were standing at the wall and sitting on the floor in the aisle). The room was “allowed to” host 150 people (sign at the wall) but there were at least 250 in there :-). Glad that there was no firefighter around. Well, the air got rather bad after ten minutes ;-). The talk itself went extremely well, I was right in time and the audience had a lively discussion that I merely moderated (many questions trying to pinpoint flaws were actually answered by the audience :-)). That was really enjoyable.


Generally, I really enjoyed SC this year, I have had so many meetings that I was barely able to check the show-floor for goodies. New Orleans was also great (well, my hotel was, let’s say “suboptimal”, but it was very cheap). I’m looking forward to next year!

PROPER 2010/EuroPar Workshop in Ischia, Italy

I am just back from the PROPER workshop in conjunction with EuroPar in Ischia. I have to say that it was absolutely awesome and want to thank my sponsors, Andreas Knuepfer and VI-HPS, again. The joy was even multi-dimensional, first, my keynote went very well and inspired many new ideas. Second, the following talks inspired even more ideas (especially Allen’s presentation). Third, the place was just beautiful (it was somewhat strange to be in a resort among the tourists and talk about CS topics. Fourth, I met many old friends and colleagues and also got to talk to Arnold Rosenberg about graph separators briefly. I loved it even though the travel was very stressful. My travel to Ischia took 25 hours (driving by car to IND, flying to Paris-CDG, flying to NAP, taking the bus to the ferry, ferry to Ischia, Bus to the hotel). The way back was the same order of magnitude. Given that I stayed only 36 hours on the island, the trip seems rather crazy. But hey, I had no jetlag after coming back :-).

Here are some impressions:ischia1
The hydrofoil ferry seemed pretty fast but wasn’t actually. Well, I fell asleep immediately after a 23 hours travel without any sleep.

The room where I presented the keynote :-).

The food was awesome! Fish, fish and more fish. Even fish-fries (which tasted like french, aehem freedom fries and were somewhat addictive).

The main attraction on Ischia. Well, I didn’t actually find the time to visit it, too much chatting going on … but I’ll probably get there another time.

Hot Interconnects 2010 and Tutorials at Google

This year’s Hot Interconnects Conference was very special. Not only was it at Google but I was in the committee as tutorials chair. The conference was very good and I really enjoyed the keynotes and the invited talks on Exascale interconnects and the many conversations I had. The tutorials also went very well. Here are some impressions:

Raj Jain’s Future Internet tutorials.

A Google bike, it looks even funnier when I rode it ;-).

The facility.

LSAP’10 (HPDC’10) + Argonne Visit

This week, I attended the Workshop on Large Scale Application Performance in Chicago. I was shocked when I arrived at HPDC (sidenote, I took the train again and it was great!): everything seemed to be about Cloud or Grid or a combination of those (+Life Science). I still don’t fully understand what all this stuff is about and what the fundamental scientific problems are. Well, the workshop was very good! I really enjoyed Barton Miller’s keynote about his MRNet research. It’s good work! I also enjoyed listening to the other workshop papers. My talk went really well (I was a bit over-time but that wasn’t bad). We (Timo, Andrew and me) even got the best paper award for our work! That was nice and unexpected.

All-in-all, it was a really good workshop!

I visited Argonne the next day and gave a talk about Next Generation Collective Operations. This was also very entertaining and it was great to be there. I had some really good conversations with some folks. Thanks for inviting me! I completely forgot to take a picture …

AMP’10 and SC’10 PC meeting

This weekend, I attended the Advances in Message Passing workshop and the Supercomputing 2010 PC meeting. AMP was in Toronto and the SC meeting in New Orleans. Well, and the schedule was suboptimal. I had to leave AMP early and catch the last flight from Toronto to New Orleans (7pm). But AMP was clearly worth it! It had a couple of very interesting papers and our own contribution fir very well too! I gave the talk together with Jeremiah (which was an experiment ;-)) — and it was a complete success!
The hotel was also funny, it was inside a shopping mall, here’s the view “outside” the window:
Too bad that we had to leave early. Btw., I spent less than 23 hours in Toronto … and two of the in the US immigration! Yes, the US immigration is *in Toronto* (wtf!). And of course, we didn’t arrive two hours early at the airport … man, catching the plane was really close (they delayed it by 20 minutes because we were not the only ones who had that problem). This is really weird …

The SC meeting was very nice. I met many friends and colleagues and had many good discussions. New Orleans is not really the nicest place I have been to. I tried to save money and stayed in the “Bourbon Inn” — well, on Bourbon Street. I did not know what Bourbon street meant when I booked the hotel :-/. Well, it meant no sleep until around 3am :-(. The street is full of night- and stripclubs … kind of odd when you walk back to the hotel after a full day of meetings. Well, I survived (and saved $150). Also, taking the bus to the airport was an adventure. I also survived this one :-). Bourbon street (the camera didn’t really work because it was *extremely* humid!).

Late Post: IPDPS’10 PC Meeting

I guess I have to mention the craziest PC meeting I attended so far: IPDPS’10. Cindy Phillips, the PC chair scheduled the meeting for Friday 12/6/09 in Albuquerque (a while ago). We met at 6:30am at the hotel (I flew in late the day before and didn’t get too much sleep … which wasn’t really too good. The meeting had only minimal breaks scheduled (10 mins breakfast, 30 mins lunch, etc.) and we started out very slow with the good papers (and spent way too much time on clear accepts – as usual :-)). Well, the conference also received a record-submission of more than 500 papers … my track (Software) was the heaviest. The meeting was very professionally managed by Cindy, good job! However, the number of submissions was just overwhelming. If we assume a 9 hour meeting, we would have about 1 minute per paper which seems very unrealistic. We spent on average more than three minutes and sometimes much longer. Well, it was evening by the time we were down to the complicated “middle-field”. All in all, the meeting took longer than 17 hours and was extremely exhausting. I think we made good decisions and selected a good program. It should have been a two-day meeting though ;-).

However, IEEE made up for my stress and gave me a certificate of appreciation :-). See

Welcome to Blue Drop!

We got our POWER7 780 (MR) System on Friday and I just logged in :-). I’m alone on something like this:

htor@bd01:~> w
 20:49:12 up 1 day,  1:01,  1 user,  load average: 0.00, 0.00, 0.00
htor     pts/0     20:35    0.00s  0.04s  0.01s w
htor@bd01:~> cat /proc/cpuinfo 
processor       : 0
cpu             : POWER7 (architected), altivec supported
clock           : 3864.000000MHz
revision        : 2.1 (pvr 003f 0201)

processor       : 1
cpu             : POWER7 (architected), altivec supported
clock           : 3864.000000MHz
revision        : 2.1 (pvr 003f 0201)
processor       : 127
cpu             : POWER7 (architected), altivec supported
clock           : 3864.000000MHz
revision        : 2.1 (pvr 003f 0201)

timebase        : 512000000
platform        : pSeries
model           : IBM,9179-MHB
machine         : CHRP IBM,9179-MHB

It’s SMT=4 though (so “only” 32 cores) but with sweet 128 GiB memory. With 4 FMAs per cycle, that’s 983.04 GF/s, nearly one TF in a single “rack” (that thing below)!

I particularly like the name … we all hope that the drop will quickly fill up a bucket full of water(s) :-).

(credits: Steve Kleinvehn, original)

PPoPP 2010

The reason for my travel to India was attending the PPoPP conference which was held in conjunction with HPCA at the Indian Institute of Science in Bengaluru. Most keynotes and the opening session was shared between the two conferences and I really liked the concept of having a hardware and a programming conference jointly. It induced some interesting discussions for me. They even got a former Indian president to speak at the opening ceremony, here’s an impression:

The PPoPP program was assembled by Mary Hall who had the interesting task of assigning the reviews for a record submission (50% more than the previous year). Here are some statistics on Mary’s slide:

The conference was excellent, actually (one of?) the best conferences that I attended so far. I liked all papers (one was borderline but still ok) which is pretty rare. All in all, just excellent!

The food was great as I said before and the social event was held at an old castle (which was oddly only reachable through a terrible dirt road … and heavily guarded again). Here are some impressions from the castle and the evening program:

That’s it, a short and good conference! I also liked the single-track layout of the talks (even though some sessions were really long ;-)).

How to cite URLs (links) in scientific papers

After studying the Chicago Manual of Style (especially the references section), I decided on the following format to cite URLs.

There are two cases:

You cite a webpage (URL) only

1. the author of the webpage followed by a period (this is optional because it’s often impossible to determine authors of a webpage)
2. the title of the page (this allows some freedom too if the webpage title is not satisfying) followed by a period
3. the URL in typewriter font (including http:// because some URLs are ftp://)
4. the date when the URL was last checked (month seems sufficient)

An example would be:
“MPI Forum. Message Passing Interface (MPI) Forum Home Page. http://www.mpi-forum.org/ (Dec. 2009)”

Example bibtex:

  author = {{MPI Forum}},
  title = {{Message Passing Interface (MPI) Forum Home Page}},
  howpublished = {{\tt http://www.mpi-forum.org/} (Dec. 2009)}

You cite a document which is (only) accessible online

1. the author of the document followed by a period
2. the title of the document followed by a period
3. the URL in typewriter font (including http:// because some URLs are ftp://) preceded by “available at: ”
4. the date when the URL was last checked (month seems sufficient)

An example would be:
“MPI Forum. MPI: A Message-Passing Interface Standard. Version 2.2, September 4th
2009. available at: http://www.mpi-forum.org (Dec. 2009).”

Example bibtex:

  author={{MPI Forum}},
  title={{\textsf{MPI}: A Message-Passing Interface Standard. Version 2.2}},
  note={available at: \url{http://www.mpi-forum.org} (Dec. 2009)},
  month={September 4th},