How fast are Linux pipes anyway?
In this post, we will explore how Unix pipes are implemented in Linux by iteratively optimizing a test program that writes and reads data through a pipe.1 We will begin with a simple program with a throughput of around 3.5GiB/s, and improve its performance twentyfold. The improvements will be informed by profiling the program using Linux’s perf tooling.2 The code is available on GitHub. The post w
Speeding up `atan2f` by 50x
2021-08-16 Speeding up atan2f by 50x \mathrm{atan2} is an important but slow trigonometric function. However, if we’re working with batches of points and willing to live with tiny errors, we can produce an \mathrm{atan2} approximation which is 50 times faster than the standard version provided by glibc. Perhaps more impressively, the approximation produces a result every 2 clock cycles. This is ac
Threading responsibly
async also provides a plethora of useful combinators that should be in the standard toolkit of every Haskell programmers, such as race, concurrently, the Concurrently Alternative Applicative, and many others. Some async patterns # Finally, I want to show some patterns that are common and that will hopefully give a bit of an idea of how async can be used to easily implement complex tasks. If you’re
Agda by Example: λ-calculus
and so on. de Bruijn notation is a terrible device for humans to use directly, but it is often more convenient when dealing with terms mechanically. When parsing a language it is easy to go from names to nameless, so that we can have the best of both worlds. Thus we will have: infixl 80 _·_ data Syntax : Set where -- A variable, the ℕ being a de Bruijn index. var : ℕ → Syntax -- A number literal.
Agda by Example: Sorting
2013-04-01 Agda by Example: Sorting Agda? # The Haskell programmer is used to the pleasure of collaborating with a nice type system. Haskell itself hits quite a sweet spot of expressivity and manageability—type inference is (mostly) decidable, no subtyping, etc. However, in the past 30 years, new systems have been emerging that allow the user to encode many more properties at the type level. In fa
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Waiting for many things at once with `io_uring`
How to stop Linux threads cleanly
The essence of Reed-Solomon coding
When `static` makes your C code 10 times faster
Reliably allocating huge pages in Linux
Quick and dirty backpropagation in Haskell
Beating the L1 cache with value speculation
Graphs: a Balancing Act