NP-Incompleteness
Newsletter
26 Sep 2026
I’ve been using RSS on and off with Feedly but I often forget to check it. I have had more success with newsletters, where I receive posts directly in my email. A recent example is Philip Su’s Molochinations which uses Substack, which offers newsletters out of the box.
I don’t use Substack and didn’t want to pay for a service to add this feature, so decided to explore creating one from scratch, using AWS infra. In this meta post, I’ll describe a serverless architecture that implements this.
Why Do I Care About Names?
20 Sep 2026
In The Pleasure of Finding Things, Richard Feynman recounts a childhood event in which a boy comes to him and asks “See that bird, what kind of bird is that?” and Feynman concedes he has no idea, and the boy proudly answers himself “It’s a brown-throated thrush” and that “Your (Feynman) father doesn’t tell you anything”.
Feynman pointed out that the boy knew about the name of the bird but did not know anything else about it and used it to illustrate shallow knowledge. Later in life he even joked that this attitude caused him trouble because he often didn’t know the conventional names for effects in physics, but understood them once someone described what the effect actually was.
In this post I’d like to reflect on why I think names can be beneficial.
Linux Memory Reclamation
11 Sep 2026
For most operating systems, when memory usage grows beyond what the hardware can support, the kernel starts swapping, i.e. moving data from memory to disk. In this post, we’ll study how the Linux kernel does this, as part of the more general memory reclamation process. We’ll also cover the memory allocation flow, because memory reclamation is just one part of it, one of the unhappy paths.
First, we’ll go over the different components involved, and then how they fit together in the memory allocation flow and then memory reclamation via swap and zswap.
LZ77
05 Sep 2026
Jacob Ziv and Abraham Lempel were both faculty at the Technion in Haifa, Israel, when in 1977 they published a paper called A Universal Algorithm for Sequential Data Compression in which they described a compression algorithm which, unlike Huffman coding, doesn’t rely on knowing the frequency of symbols upfront.
Ziv was an information theorist from the Electrical Engineering department while Lempel was part of the Computer Science department. They met due to their interest in lossless compression and Ziv said [1] that their skills complemented each other well:
I knew all about information theory and statistics, and Abraham was well-equipped in Boolean algebra and computer science.
This algorithm is now known as LZ77 (their last name initials + the year the paper was published). A popular algorithm called DEFLATE combines LZ77 with Huffman and is used by tons of software including gzip, git, png, etc.
In this post we’ll cover the LZ77 algorithm.
CacheLib
28 Aug 2026
CacheLib is an open-source C++ library from Meta for constructing in-process caches. At a high level, we can think of it as a hash table in memory with the option to spill to flash storage.
In this post we’ll study this library, mainly the in-memory portion based on the paper The CacheLib Caching Engine: Design and Experiences at Scale [1] and the code.
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