Communications of the ACM
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How the “Frontier” Became the Slogan of Uncontrolled AI
Artificial intelligence (AI) has been billed as the next frontier of humanity: the newly available expanse whose exploration …
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...
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...
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...
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...
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...
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...
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...
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...
From Daniel Lemire's Blog
Science and Technology links (September 1st, 2018)
Our PCs and servers run x64 processors, most of them made by Intel and AMD. In my home, all my x64 processors are made by Intel… except the processor of my PlayStation...
From Daniel Lemire's Blog
Lexicographical comparisons vs. equality checks: the long-string case
It is a common problem in software to check whether two pieces of data are byte-by-byte identical. Standard libraries provide function to compute a lexicographical...
From Daniel Lemire's Blog
AVX-512 throttling: heavy instructions are maybe not so dangerous
Recent Intel processors have fancy instructions operating over 512-bit registers. They are reported to cause a frequency throttling of the core where they are run...
From Daniel Lemire's Blog
Science and Technology links (August 24th, 2018)
There is water on the surface of the Moon. This is important because if you want to build a long-term base on the Moon, having access to water is a great asset....
From Daniel Lemire's Blog
Trying harder to make AVX-512 look bad: my quantified and reproducible results
Intel’s latest processors have fancy instructions part of the AVX-512 family. The AVX-512 instructions are useful for numerical work and sophisticated computing...
From Daniel Lemire's Blog
Avoid lexicographical comparisons when testing for string equality
By default, programmers like to compare their bytes and strings using a lexicographical order. “Lexicographical” is a fancy word for “dictionary order”. That is...
From Daniel Lemire's Blog
Performance of ranged accesses into arrays: modulo, multiply-shift and masks
Suppose that you wish to access values in an array of size n, but instead of having indexes in [0,n), you have arbitrary non-negative integers. This sort of problems...
From Daniel Lemire's Blog
Science and Technology links (August 19th, 2018)
Publishing your ideas is a central component of science and scholarship. To make it easier to publish, some companies and organizations have begun to offer pay-to...
From Daniel Lemire's Blog
The dangers of AVX-512 throttling: a 3% impact
Intel’s latest processors come with powerful new instructions from the AVX-512 family. These instructions operate over 512-bit registers. They use more power than...
From Daniel Lemire's Blog
Fast strongly universal 64-bit hashing everywhere!
In software, hashing is the process of taking a value and mapping it to a random-looking value. Suppose you are given 64-bit integers (a long in Java). You might...
From Daniel Lemire's Blog
The dangers of AVX-512 throttling: myth or reality?
Modern processors use many tricks to go faster. They are superscalar which means that they can execute many instructions at once. They are multicore, which means...
From Daniel Lemire's Blog