Visualizing algorithms

January 29th, 2015 admin

Algorithms Visualizaton (Sampling, Shuffling, Sorting, Maze):
Bloom Filter Visualization:
Cuckoo Hashing Visualization:
Fourier Transform:

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Education and learning

January 14th, 2015 admin

Education is the journey from not knowing anything (ignorance) to not knowing what you do know and knowing what you don’t (active learning) to knowing what you do know and not knowing what you don’t know (false pride) to knowing what you do know and knowing what you don’t (grateful humility).

Gain in absolute knowledge comes with a loss in relative knowledge. The more you learn, the more you realize how much more there is.

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Inferences from paycheck swings

January 9th, 2015 admin

In the US, if you see a drop in your January paycheck (compared to the last paycheck in the previous year), you may want to keep this news to yourself. The reason is that it may reveal something about your salary.

Typically, a noticeable drop in take home pay starting with the first paycheck of the year is ascribable to the additional amount you pay as FICA tax (Federal Insurance Contributions Act), also known as Social Security tax. Every year, you pay 6.2% of every paycheck until you hit the limit of $7347 (limit as of year 2015 – keeps going up by small amounts each year). The greater your salary, the earlier in the year you will reach the limit and therefore stop contribution to FICA. If your salary is around $118K per year you will hit that limit in your last paycheck of the year (6.2% of 118K ~= the limit of $7347). And then a new year starts and you do not notice any dip in your net pay since you will start paying the same amount in January. If, however, your salary is more than $118K then you hit the $7347 limit sooner in the year and therefore you will both see an increase in take home pay sometime during the year, as well as the subsequent drop at the beginning of the next year. So by giving out information that you saw this drop in net pay in January, you may be telling the world that you make more than 118K (including bonuses etc.). What’s more, if you reveal when during the year you saw the bump in the paycheck, you may be revealing your actual annual salary (with some margin of error, of course). I found it interesting that you do not have to mention how much the salary increased by, just the paycheck during the year in which you noticed the bump – and then you can figure out the rest. Could be turned into an interesting math puzzler.

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The Flight

December 27th, 2014 admin

Here are a few thoughts on the trades we make between freedom, stability, responsibility and joy.

The fancy flight of a floating seed
in a chance or careful sow,
is lost to roots that hold and feed,
free, in place alone, to grow.

With eager arms the sun it seeks
in a lonely skyward plough
until the littlest songbird speaks
in praise of its shady bough.

The tree bends low in a shared embrace
weeping with that sage delight
at the thousand travels it shall grace
until the final freeing flight.

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PhD Dissertation Document

July 19th, 2013 admin

Here is the latest version of my PhD Dissertation document and slides for the defense talk. This way you can access the latest version of this document without me having to email it individually. I foresee these documents to change over the next few weeks (perhaps until August 6th for the slides and August 20th for the dissertation) as I refine them.

Click this link to download the dissertation – AnilKrishna-Dissertation-Document
Click this link to download the talk slides – AnilKrishnaPhDDefenseSlides

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A Song for Computer Architects

May 28th, 2013 admin

(Set to the tune of Billy Joel’s “We Didn’t Start the Fire”)

Von Neumann, Wire-delay, Context Switch, Tag Array,
Custom ASIC, Weighted Speedup, Continual Flow,
Issue, Reservation Station, SuperScalar, Speculation,
Load Queue, Store Queue, Instruction Window,
Rounding Error, IQ CAM, Non-volatile SRAM,
Byte Code, VLSI,  Dirty Bit per Cacheline,
Branch Predictor, TLB, Flush and Recovery,
Morris Mano, Forward Slice, Signal ACK or RETRY
We didn’t short the wire
It’s been getting hotter
We should cool it with water
And don’t call me a liar
Yes, while I did write it,
prior art was cited
Read the rest of this entry »

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Tutorial on Cache Coherence and Scaling Issues

June 4th, 2012 admin

Cache coherence is a concept in Computer Architecture that deals with managing multiple copies of data in a computer system. This short tutorial is suitable for someone who is aware of the basic concept and is only trying to brush up on it. The focus of the tutorial is introducing the two classic approaches to Cache Coherence and identifying what happens as more and more caches must be kept coherent. Click this link – TutorialOnCacheCoherence

Posted in Information, Tidbits, Tutorials | 1 Comment »

Tutorial on the concept of Bloom Filters

June 4th, 2012 admin

Bloom Filters are used in many places in Computer Hardware design and elsewhere. I am sure we use it in day-to-day life without realizing it or giving it a fancy name. Here is a simple, lateral, introduction to this commonsensical concept via a concocted real-life, non-computer-architecture example. Click this link – TutorialOnBloomFilters

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A simple problem that led us to Ramanujan’s work on Integer Partitioning

September 12th, 2010 admin

Raghu, my cousin, sent me an email with the following problem a few months ago.


Manish was on his way to an interview. On the way, he encountered his long lost cousin, Vijay, whom he hadn’t met in more than a decade. They started catching up on lost time. Manish learned that Vijay had 3 sons. When he asked about their ages, Vijay replied, “You’re going for an interview, right? Consider this a trial question. Figure out their ages from this: The product of the ages of my three sons is 36.” To this, Manish grumbled that he needed more information. Vijay, then, pointed to a sign board across the street that displayed the address of the area and said that the sum of the ages of his three children was equal to the last two digits of the pin code (zip code) of that area. Manish demanded still more information. Finally, Vijay said, “My eldest son wore a black shirt today. This is all I can tell you.”

What were the ages of the three children? Read the rest of this entry »

Posted in Family, Tidbits, Tutorials | 2 Comments »


September 1st, 2010 admin

“Ammamma…Boost…”, I would ask her for a hot malt beverage, as she would get busy in her tiny kitchen after her short afternoon nap on the hard concrete floor, with a strategically placed pillow for her head. Ammamma means maternal grandmother in my mother tongue, Telugu. Amma is mom, and ammamma is, literally, momom. She would then get busy preparing the late afternoon coffees for the elders, starting with the eldest – Tatagaru, and Boost for the kids. Although I mostly saw her only over summer holidays, this particular aspect of her routine was probably eternal. In fact, all her routines were seemingly eternal yet inexplicably fresh every time. She would hunker down at the old, grime-laden, two-burner gas stove sitting on the floor of her tiny kitchen and with what seemed like an impossibly tiny collection of utensils, groceries and gadgets, came up with the most exquisite of dishes. Simple fare it always was, and she was not a great cook, but the taste of her cooking was earthy and heavenly. Vegetables of all manner were shallow fried. Coffee and Boost was not served before being poured several times, alternating between two tumblers to generate froth (steamed milk). “Boost tagutawa, Kishtappa, aain?”, she would ask. The “aain?” was kind of like Amitabh Bachchan’s pan-laden mouth confirming something – “aain?”.

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Posted in Events, Family | 13 Comments »