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Measuring the memory-level parallelism of a system using a small C++ program?
From Daniel Lemire's Blog

Measuring the memory-level parallelism of a system using a small C++ program?

Our processors can issue several memory requests at the same time. In a multicore processor, each core has an upper limit on the number of outstanding memory requests...

Science and Technology links (November 3rd, 2018)
From Daniel Lemire's Blog

Science and Technology links (November 3rd, 2018)

Bitcoin, the cryptocurrency, could greatly accelerate climate change, should it succeed beyond its current speculative state. Crows can solve novel problems very...

Science and Technology links (October 28th, 2018)
From Daniel Lemire's Blog

Science and Technology links (October 28th, 2018)

If you take kids born in the 1980s, who do you think did better, the rich kids or the poor kids? The answer might surprise you: The children from the poorest families...

Is WebAssembly faster than JavaScript?
From Daniel Lemire's Blog

Is WebAssembly faster than JavaScript?

Most programs running on web sites are written in JavaScript. There are still a few Java applets and other plugins hanging around, but they are considered obsolete...

Science and Technology links (October 20th, 2018)
From Daniel Lemire's Blog

Science and Technology links (October 20th, 2018)

Should we stop eating meat to combat climate change? Maybe not. White and Hall worked out what happened if the US stopped using farm animals: The modeled system...

Validating UTF-8 bytes using only 0.45 cycles per byte (AVX edition)
From Daniel Lemire's Blog

Validating UTF-8 bytes using only 0.45 cycles per byte (AVX edition)

When receiving bytes from the network, we often assume that they are unicode strings, encoded using something called UTF-8. Sadly, not all streams of bytes areContinue...

Validating UTF-8 bytes (Java edition)
From Daniel Lemire's Blog

Validating UTF-8 bytes (Java edition)

Strings are just made of bytes. We send and receive bytes over the network all the time. If you know that the bytes you are receiving form a string, then chances...

Nobel-prize winner Rommer on innovation and higher education
From Daniel Lemire's Blog

Nobel-prize winner Rommer on innovation and higher education

Rommer was one of the the winners of the Nobel prize in economics this year (2018). He wrote about higher education and innovation. One of his proposals is theContinue...

Science and Technology links (October 13th, 2018)
From Daniel Lemire's Blog

Science and Technology links (October 13th, 2018)

Chronic exposure to canola oil results in a significant increase in body weight and impairments in working memory… in mice. (Source: Nature) Belly fat is not just...

Smart bracelet: my experience with the Mi Band 3
From Daniel Lemire's Blog

Smart bracelet: my experience with the Mi Band 3

I was an early adopter of fitness bracelets with heart-rate monitoring. I use them to track my heart rate at rest. You heart rate should be around 65 if you are...

Science and Technology links (October 6th, 2018)
From Daniel Lemire's Blog

Science and Technology links (October 6th, 2018)

Ibuprofen extends lifespan in many species including, maybe, human beings. Donna Strickland is the third women to win a Nobel prize in Physics. It appears thatContinue...

Quickly parsing eight digits
From Daniel Lemire's Blog

Quickly parsing eight digits

In my previous post, I described how we can quickly determine whether eight characters are made of digits (e.g., ‘13223244’). It takes a bit over 2 cycles. Suppose...

Quickly identifying a sequence of digits in a string of characters
From Daniel Lemire's Blog

Quickly identifying a sequence of digits in a string of characters

Suppose that you want to quickly determine a sequence of eight characters are made of digits (e.g., ‘9434324134’). How fast can you go? In software, charactersContinue...

Science and Technology links (September 30th, 2018)
From Daniel Lemire's Blog

Science and Technology links (September 30th, 2018)

Oculus is launching a new standalone virtual-reality headset next year, the Oculus Quest. It is the price of a console like the Nintendo Switch, and might haveContinue...

Science and Technology links (September 22nd, 2018)
From Daniel Lemire's Blog

Science and Technology links (September 22nd, 2018)

Apple benefits from the chip-making technology of a company called TSMC. This company has surpassed Intel in transistor density. Thus, in some sense, the microprocessors...

On the state of virtual-reality gaming
From Daniel Lemire's Blog

On the state of virtual-reality gaming

For nearly two years, I have been trying a wide range of video games in a virtual reality setting. Our lab. in Montreal has some permanent space dedicated to the...

Science and Technology links (September 15th, 2018)
From Daniel Lemire's Blog

Science and Technology links (September 15th, 2018)

I was told repeatedly throughout my life that the normal body temperature was 37.5°C. This estimate is over a hundred years old and flawed. It is off by one degree...

Science and Technology links (September 8th, 2018)
From Daniel Lemire's Blog

Science and Technology links (September 8th, 2018)

Most research articles are not available for free to the public, even when the research was fully funded by the public. To legally access research articles, one...

AVX-512: when and how to use these new instructions
From Daniel Lemire's Blog

AVX-512: when and how to use these new instructions

Our processors typically do computations using small data stores called registers. On 64-bit processors, 64-bit registers are frequently used. Most modern processors...

Per-core frequency scaling and AVX-512: an experiment
From Daniel Lemire's Blog

Per-core frequency scaling and AVX-512: an experiment

Intel has fancy new instructions (AVX-512) that are powerful, in part for heavy numerical work. When a core uses these heaviest of these new instructions, the core...
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