Blog posts

EnvironmentError: IOError: usb rx6 transfer status: LIBUSB_TRANSFER_OVERFLOW

If you are facing the following problem, that means the FPGA tried to load too much data into the DMA FIFO in the Cypress FX3 (USB chip) and got crashed. This might be resolved in some later versions of UHD, but you can use below workaround a suggested by Michael at here.

terminate called after throwing an instance of 'uhd::io_error'
  what():  EnvironmentError: IOError: usb rx6 transfer status: LIBUSB_TRANSFER_OVERFLOW
Aborted (core dumped)

use the command utils/b2xx_fx3_utils --reset-device if you ever have to Ctrl-C your application


Bad font: Type3 font “DejaVuSans” first referenced on page 3

ACM or ScholarOne’s manuscript central does not accept Type3 font. To solve this,

You could use either

matplotlib.rcParams['pdf.fonttype'] = 42


matplotlib.rcParams['text.usetex'] = True

One of the best books to understand the history of humankind

A favorite from the recent reads of my summer.
Sapiens: A Brief History of Humankind, by Yuval Noah Harari.
The book brings back the memories from the stone age to ice age to agricultural revolution to scientific revolution. I was fascinated to learn about the details of how the homo sapiens spread around the world during the ice age and got separated into virtual worlds until few hundred years ago. It was a one of the thought-provoking experience I have ever had.
I highly recommend this for each and every book lover. Happy #BookLoversDay 🙂 🙂

The Beginning of my PhD Journey!

The thought of PhD: After three years of fantastic experience in a startup, I realized that I am more interested in research and decided to pursue PhD. Now, the obvious question that appears to anyone is PhD in India or a foreign land. It was a hard choice. I have to leave my family, relatives and all of my friends If I have to choose foreign. To be honest, I was more worried about the food 🙂 Anyway, for whatever reason I decided to step foot on a foreign country. Now, where to go? how to go? what is the procedure to apply for a PhD program in foreign country(s)? A storm of questions in my head and have no clue for any of them.

 The immature happiness: Thanks to my friends, I got guidance from all along. At first, I decided to join one of the European institutes and started preparing for IELTS (a TOFL version of US). I got my GRE and IELTS scores (not so bad). So, now what to do with these scores? Got an advice that forward your resume with these scores to professors and ask if there is any research position in their group. Took that blindly and started approaching professors from TU Berlin, EPFL, INRIA Sophia, UCL and many others.  While I was not getting any response from any of these professors, I learned the importance of recommendation letters, statement of research purpose and a formal application procedure to the university. Meanwhile, I was also convinced that America is the place to go pursue my PhD (an obvious influence from your environs). But there is only so much of time that I had to figure this all out. It was already September 2015. I wanted to start my PhD as soon as possible. But, I have to wait for another year, If I want to apply formally and get an admission and join in Fall 2016. So, guess what, I again started my inquiry emails for research position to American university professors as well. Lucky this time, a professor from Missouri University of S&T, Rolla offered me PhD position. That’s it, I was so excited and instantly quit my job and started my preparation for the dream foreign land for almost everyone in the world.

The road not taken: America! The place where the earth was born, my mother says. It was Christmas, the 25th Dec the day I landed in Missouri. Silly me, was expecting full of people celebrating as if it were an Indian festival. Anyway, soon after I landed,  the first thing I noticed is that the roads are very clear and spacious. And of course the cold winter. Thanks to the social websites or apps, I made few friends already even  before landing in Missouri. I also got the comfort of speaking in my mother tongue and did not care enough to explore to meet new people. I have never met a foreigner before and have never talked to them either. Although, my new lab mates were Chinese, I could almost never get a chance to speak to them unless in our group meetings. It was almost no difference except I get to see few foreign people here and there but never talk. Things are normal until I hear the news from my adviser that she is going to move. I didn’t know what to do. Should I go with my adviser or should I stay. Friends suggest that I should consider some other better universities. For a moment, I thought I might be going back to India if I don’t get a research position anywhere. While I was talking to few professors, I got a last minute chance to apply for Stonybrook university in June, 2016 (For a Fall admission it was a rare situation). Believe me or not, I got an admission notification in two days of my application. I can confidently say that my admission to Stonybrook could be the quickest offer ever.

A new experience: Time to New York now, hah! This time I actually felt a difference from India. It was overwhelming to see so much diversity after I landed in New York. But, soon after I reached the campus, I realized that almost 90% of the graduate students are Indians and Yet I have almost no one to talk to in my mother tongue which is Telugu. Funnily enough, I am used to listen to more Hindi words in a foreign English speaking land unlike my hometown where Telugu is the only language I was exposed to. Admittedly, I got new friends with new cultures, new languages, and everything new. I can say now, I have friends from multiple countries — US, Brazil, Russia, Ukraine, China, Korea, Taiwan, Bangladesh, Pakistan, Turkey, Iran, Egypt, Greece and what not. Finally, with new energy and enthusiasm, I started my new career and hope to have a successful journey for next 5 to 6 years of my PhD study.

Summary: Split/Merge-System Support for Elastic Execution in Virtual Middleboxes, NSDI’13

Split/Merge presents an abstraction for virtual middleboxes that splits the state among replicas and dynamically re-balances both existing and new flows. They classify the middleboxes’ state into internal and external, and the external state is further divided into partitioned and coherent (global.. E.g., stats counter). All the three types of state are stored in each replica— the internal state need not be synchronized while the external state must be consistent (strong or eventual) among all replicas.  They create an application level library called Freeflow that supports creating and destroying of VMs while balancing the load (scaling-out and -in). They show the performance improvement by using an IDS and two other synthetic middleboxes. Section 2 gives an excellent anatomy of a typical middlebox and the overview of these three middleboxes used.

Split/Merge has four components. One, an application library that handles state related challenges (state classification and partitioned state must be moved between replicas etc). Second, an SDN controller to reflect the forwarding path changes (to route the traffic to appropriate replica). Third, an orchestrator that implements an elasticity policy which decides when to scale and when to migrate flows. Four, a VM manager that implements an actual creation and deletion of middlebox replicas.