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Blog/April 2013/Apr 19th

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Apr 19th (See this week's devar torah) Comments or questions? Click here!


Hi, again!

An excellent week here in the Land: the modern State of Israel's 65'th birthday, fine weather and interesting work!

We started the week normally, going to work; and we anxiously anticipated the national holiday (away from work) on Tuesday. We (Esther and I, that is) figured we would show solidarity with our city's mayor at an event at E1. But Sarah had other plans. That morning she came downstairs, and said with a croaking and painful voice that she couldn't swallow and didn't sleep at all, and could we please go to the emergency clinic as soon as it opened. Being a national holiday, nothing much was open, so we had to wait a while.

When the clinic was open, we went there; the doctor diagnosed Sarah with tonsilitis, and gave her medication for the pain and swelling, as well as a prescription for antibiotics. However, being a national holiday, there was only one pharmacy in the entire Jerusalem area which was "on duty"... and it was on the other side of Jerusalem from us. Never mind, I went there to get her the drugs -- and after a couple hours she felt a lot better. The next day she called the clinic to get the lab report on her throat-swab and they informed her it was not bacterial, so she should stop taking the antibiotics. Needless to say, we didn't manage to show our solidarity with the mayor. Oh, and by the way: Jerusalem is a city with 800,000 inhabitants but only one on-duty pharmacy.

Work has been very interesting -- to me and my team as well as to the CEO. We managed to figure out to some extent why our application was running more slowly on the faster machines.

Technical aside: a computer program uses a number of resources, which interact in important ways. First is the "CPU" -- the "brain". It has a base "speed" (given in MHz or GHz, "the faster the better"). Modern CPUs run at speeds on the order of 2.5 GHz (billion cycles a second). The second is "RAM" -- the "memory". That's where the program is loaded so it can run, and where data are loaded so they can be accessed by the CPU. The third is "disk". This is the long-term storage, where files are saved. CPU is much faster than RAM, which is must faster than disk -- always. So programs which need to run as quickly as possible will try to maximize their CPU utilization.

In our case, we could see the CPUs were barely being utilized, and that using faster CPUs did not improve the speed (and sometimes ruined it). That led us to consider memory effects. What does that mean?

As I said, a CPU is extremely fast, much faster than the RAM it reads from. So modern CPUs have "internal RAM" called "cache", which is about as fast as the CPU, so that the CPU doesn't have to wait around for data to be read from RAM. The way it works is like this: when the CPU wants to read (say) the text "Mary had a little lamb", that text along with whatever was after it is sucked into the cache. That's great if the CPU wants the entire text. But if the CPU only wants "Mary" and then decides to look at "Fourscore and seven years ago", the cached data need to be tossed out, and new data read in. This takes an eternity (in CPU-terms). This so-called "cache miss" is the particular "memory effect" we were encountering.

So after a lot of investigation, we re-worked our code to significantly reduce cache misses, and managed to reduce the time required to 10% of what it was. That is, our code is now ten times faster! At this point, we have other things to investigate and it is likely we'll be able to make further improvements.
end technical aside...

As I said in the opening, Israelis celebrated the 65th year of the country's independence. Poll after poll indicate that Israelis are, on the whole, much happier with their lot in life than people in other countries. Considering the prevalence of wars and terrorism and locusts, you might be forgiven for wondering just what drugs are in our water supply? Here's a list of just a few of the many inventions produced in Israel's 65 short years, which may be contributing to our general happiness:

Medicine

Agriculture

  • drip irrigation, improving the lives of literally hundreds of millions of people worldwide.
  • Cherry tomatoes, developed as a 'snack food'
  • Hybrid cucumber seeds

Computers and high-tech

  • USB flash drive
  • Intel Israel produced the MMX, Centrino and Pentium CPU chips used in hundreds of millions of computers
  • Motorola Israel developed the cell-phone
  • Most of Windows NT was developed in Israel
  • VOIP (voice-over-IP), allowing people to communicate over the internet without phones
  • ICQ

Military and defense

  • The iconic Uzi submachine gun
  • The new Tavor series of submachine guns
  • Merkava tanks, helping us keep our edge against our enemies
  • The Iron Dome near-theatre anti-missile defense

These are certainly good reasons to be proud of our fledgling country -- especially considering the complete lack of inventions or advances by the entire Arab world, and that the Muslim world has done nothing positive for humanity. But it could just be that, as our Sages said, "the air of the Land of Israel makes one wise". In any case, I am proud of my country's accomplishments even while I hope for more fundamental changes for the better.

Sarah has overcome her illness, and will be spending shabbat with friends in Beit Shemesh, so Esther and I will have to fend for ourselves. We'll do a gourmet menu:
pitot, baked salmon, chicken soup, various salatim, grilled steak with fried onions and mushrooms, baked yams, spicy lentil curry, basmati rice and chocolate-covered strawberries.


Until next week,
shabbat shalom!


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