Communications of the ACM
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Critical Vulnerability in libwebp Library
Both Apple and Google have recently reported critical vulnerabilities in their systems—iOS and Chrome, respectively—that aresame…
From Daniel Lemire's Blog
Cost of a thread in C++ under Linux
Almost all our computers are made of several processing cores. Thus it can be efficient to “parallelize” expensive processing in a multicore manner. That is, instead...
From Daniel Lemire's Blog
Science and Technology links (January 25th 2020)
Scientists found a way to increase the production of new neurons in the brains of mice, effectively rejuvenating the brains of old mice. (Source: Nature) How many...
From Daniel Lemire's Blog
Filling large arrays with zeroes quickly in C++
Travis Downs reports that some C++ compilers have trouble filling up arrays with values at high speed. Typically, to fill an array with some value, C++ programmers...
From Daniel Lemire's Blog
Allocating large blocks of memory: bare-metal C++ speeds
In a previous post, I benchmarked the allocation of large blocks of memory using idiomatic C++. I got a depressing result: the speed could be lower than 2 GB/s....
From Daniel Lemire's Blog
How fast can you allocate a large block of memory in C++?
In C++, the most basic memory allocation code is just a call to the new operator: char *buf = new char[s]; According to a textbook interpretation, we just allocated...
From Daniel Lemire's Blog
Science and Technology links (January 11th 2020)
The extra wealth that ones acquires by attending college is now estimated to be indistinguishable from zero. The authors control for the parent’s education andContinue...
From Daniel Lemire's Blog
How I teach database design
Most software runs on top of databases. These databases are organized logically, with a schema, that is a formal description. You have entities (your user), attributes...
From Daniel Lemire's Blog
My Science and Technology review for 2019
I like to end every year with my selection of the most significant science and technology events. In 2019, you could buy a computer from Apple with 1.5 terabytes...
From Daniel Lemire's Blog
Science and Technology links (December 21st 2019)
The number of research papers with more than 1000 authors is increasingly quickly and reaching many fields. Researchers at Facebook use neural networks to solve...
From Daniel Lemire's Blog
Xor Filters: Faster and Smaller Than Bloom Filters
In software, you frequently need to check whether some objects is in a set. For example, you might have a list of forbidden Web addresses. As someone enters a new...
From Daniel Lemire's Blog
A look back to my 2010 predictions for 2020
Back in 2010, I wrote a post Who is going to need a database engine in 2020? Let me revisit some of my 2010 statements. Apple will sell desktops with 1 TB of RAM...
From Daniel Lemire's Blog
Science and Technology links (December 14th 2019)
The computation capacity needed by artificial intelligence doubles every 3.4 months. In parallel, we are making fast progress in hardware and software: what took...
From Daniel Lemire's Blog
Are 64-bit random identifiers free from collision?
It is common in software system to map objects to unique identifiers. For example, you might map all web pages on the Internet to a unique identifier. Often, these...
From Daniel Lemire's Blog
Amazon’s new ARM servers: Graviton 2
Most servers on the Internet run on x64 processors, mostly made by Intel. Meanwhile, most smartphones run ARM processors. From a business perspective, these are...
From Daniel Lemire's Blog
Science and Technology links (December 7th 2019)
Incredibly, there is a new simpler way to solve the quadratic formula. I used to rely on the completion of the square, but this is better! There is a video report...
From Daniel Lemire's Blog
AMD Zen 2 and branch mispredictions
Intel makes some of the very best processors many can buy. For a long time, its main rival (AMD) failed to compete. However, its latest generation of processors...
From Daniel Lemire's Blog
Instructions per cycle: AMD Zen 2 versus Intel
The performance of a processor is determined by several factors. For example, processors with a higher frequency tend to do more work per unit of time. PhysicsContinue...
From Daniel Lemire's Blog
Better computational complexity does not imply better speed
A recent magazine article presents a theoretical result: Harvey and van der Hoeven have shown that you can multiply two n-bit integers using O(n log n) complexity...
From Daniel Lemire's Blog
Memory parallelism: AMD Rome versus Intel
When thinking about “parallelism”, most programmers think about having multiple processors. However, even a single core in a modern processor has plenty of parallelism...
From Daniel Lemire's Blog