Complete archive

Archive

3,240 articles, newest first · page 17 of 54. For subject-based browsing use topics; for keyword lookup try search. Dates shown are assigned archive dates that order the library; they are not historical publication records.

2026
Feb 4, 2026 What a Connectivity Callback Reports and What It Cannot Why the operating system reports a network as available before it can reach anything, and which checks distinguish a captive portal from an outage from a broken name lookup. mobile computing · foundational
Feb 3, 2026 Borrow Checking as a Dataflow Analysis Over Places How a lifetime check becomes a liveness problem on a control-flow graph, why non-lexical lifetimes removed a class of false errors, and where the analysis still gives up. programming languages · advanced
Feb 3, 2026 Conditional Independence and the Factorization of Joint Distributions Why a joint distribution over many variables cannot be stored as a table, how independence assertions turn it into a product of small factors, and what the factored form can never represent. machine learning · foundational
Feb 2, 2026 Graph Breaks, Fallback Paths, and Numerical Drift What happens at the boundary where tracing stops, why the eager fallback does not produce bit-identical results, and how a runtime keeps two execution paths consistent. inference systems · advanced
Feb 2, 2026 Softirqs and the Per-CPU Deferred Queue How the fixed softirq vector set, the per-CPU pending mask, and the budgeted processing loop cooperate, and why running twice on one CPU is a bug rather than a race. operating systems · intermediate
Feb 2, 2026 The Comparison Sorting Lower Bound and What It Actually Counts Why comparison sorts need about n log n comparisons, how the decision-tree and adversary arguments differ, and which cost models the bound leaves out. algorithms · foundational
Feb 1, 2026 Nested Paging: Two-Dimensional Translation for Virtual Machines How a guest physical address becomes a host physical address, why the walk cost multiplies, and which workloads suffer most from the second level of tables. memory systems · advanced
Feb 1, 2026 Switching the Write Path: Cutover, Rollback, and the Point of No Return How to move writes to a replacement store without a window of two writers, what rollback actually requires after new-only data exists, and how to decide when reversal stops being possible. software architecture · advanced
Feb 1, 2026 The Virtio Split Ring: Descriptor Chaining and the Two Suppression Flags The byte layout of the descriptor table, available ring, and used ring, how descriptors chain through guest memory, and how the event-index mechanism replaces the older no-notify flags. virtualization · intermediate
January
Jan 31, 2026 Contraction Hierarchies and Preprocessing for Road Networks How contracting vertices in a fixed order adds shortcut edges that preserve all distances, and why a bidirectional search that only moves upward then answers queries with a small fraction of the work. algorithms · advanced
Jan 30, 2026 Count, for_each, and the Stability of Instance Addresses How a resource with a repetition argument becomes several state addresses, why index keys renumber on deletion while map keys do not, and what that costs at apply time. cloud infrastructure · intermediate
Jan 30, 2026 The Linearizable Register Beneath Every Coordination Primitive Why locks, membership lists, and leader election all reduce to reads and writes of one small object, and what linearizability adds that sequential consistency does not. distributed systems · foundational
Jan 29, 2026 DO-178C Objectives, Design Assurance Levels, and Structural Coverage How software level follows from failure condition severity, what the objective tables actually require at each level, and why MC/DC measures test adequacy rather than correctness. embedded systems · advanced
Jan 29, 2026 Edit Distance and the Shape of a Two-Dimensional Table How the Levenshtein recurrence fills a grid, why three neighbouring cells are enough, and how the band and Hirschberg variants trade the full matrix for time and reconstruction ability. algorithms · intermediate
Jan 29, 2026 Message Delimitation and the Mechanics of Request Smuggling How Content-Length, Transfer-Encoding, and connection close define where a message ends, and how disagreements between parsers turn that boundary into an attack. internet protocols · advanced
Jan 29, 2026 Struct Padding and the Alignment Rule Behind sizeof How alignment requirements, member order, and trailing padding determine a structure size, and why reordering members can shrink it without changing any field. systems programming · foundational
Jan 29, 2026 The Semantics of a Code Review Approval An approval is a statement with an unstated scope: which revision it applies to, which claims it vouches for, and how it goes stale when the change moves underneath it. software engineering · intermediate
Jan 28, 2026 Concurrency Limits Derived from Little's Law How the relation between in-flight requests, arrival rate, and latency produces a concurrency limit, and why an adaptive limit tracks a dependency that changes speed. backend systems · intermediate
Jan 28, 2026 DOM XSS: Sources, Sinks, and Why the Server Never Sees the Payload How client-side flow from attacker-controlled input to an executing sink bypasses server-side encoding, and which of the flow-tracking approaches can follow the value. security · intermediate
Jan 28, 2026 End-to-End Protection Information and Where the Checksum Stops How T10 protection information moves a checksum onto the wire with the data, what the guard, application tag, and reference tag each defend, and why the host still needs its own check. filesystems · advanced
Jan 28, 2026 Ladner's Theorem: Building Languages Between P and NP How to construct an NP language that is neither in P nor NP-complete assuming P differs from NP, using a slow diagonalization that delays each requirement until the padding is large enough. computation theory · advanced
Jan 28, 2026 Read-Your-Writes Across Replicated Session Stores Which consistency guarantees a session actually needs, why a replica read can undo a rotation, and how version tokens and home-region ownership keep a user from seeing their own past. backend systems · intermediate
Jan 27, 2026 Advertised Windows and Zero-Window Probing What the receive window field promises, how the receiver computes the value it advertises, and how a sender recovers when the peer advertises zero and then forgets to reopen. networking · foundational
Jan 27, 2026 Compositing and Layer Promotion: When an Element Gets Its Own Layer The rules that put an element on its own compositor layer, the memory each layer costs, and why promoting more elements can make a page slower instead of smoother. web platform · intermediate
Jan 27, 2026 Deny Wins: How One Request Is Evaluated Against Many Policy Documents The order in which identity policies, resource policies, boundaries, and organization policies combine to produce a single allow or deny, and why that order is not additive. cloud infrastructure · foundational
Jan 27, 2026 PCIe Topology and Bus-Device-Function Enumeration How a host walks a tree of bridges and switches, how each function is named by bus, device, and function number, and why configuration space is a per-function address space. hardware engineering · foundational
Jan 26, 2026 Container Roles and Nested Structure How group, region, and composite containers nest, what nesting does to landmark and heading navigation, and when a wrapper should carry a role at all. accessibility · advanced
Jan 26, 2026 How a CMOS Gate Computes with Pull-Up and Pull-Down Networks The transistor network behind a static CMOS gate, how the voltage transfer characteristic defines noise margins, and why stack height limits fan-in. hardware engineering · foundational
Jan 26, 2026 Provenance Attestations and the Trust Boundary of a Package Install What an in-toto attestation binds together, how transparency logs change the meaning of a verified install, and which attacks remain outside the model. language runtimes · advanced
Jan 26, 2026 Razborov-Smolensky and the Limits of Modulo Gates How low-degree polynomials over a finite field stand in for constant-depth circuits, and why AC0 with MOD-p gates cannot compute MOD-q for a different prime. computation theory · advanced
Jan 26, 2026 Tail Drop, Buffer Bloat, and How Much Queue a Link Actually Needs A drop-tail queue signals congestion only by overflowing, and the delay it adds while full is the latency every other flow experiences. The bandwidth-delay product gives a floor, not an optimum. networking · intermediate
Jan 26, 2026 The NTP Four-Timestamp Exchange and Its Asymmetry Limit How four timestamps yield an offset estimate, why the estimate is only as good as the path symmetry, and how the protocol decides which of several servers to believe. distributed systems · intermediate
Jan 26, 2026 Top Halves and Bottom Halves Why an interrupt handler cannot sleep, how the split between immediate and deferred work is drawn, and what each deferral mechanism costs in latency and context. operating systems · intermediate
Jan 24, 2026 Hardened Allocators and Metadata Integrity How allocator metadata becomes an attack surface, what canaries, quarantines, and out-of-band tables actually detect, and the performance each check costs. memory systems · advanced
Jan 24, 2026 Interface Drop Counters and What Each One Actually Attributes How kernels classify discarded packets into drop, error, and overrun counters, and why a clean counter set can coexist with a link that loses traffic. networking · foundational
Jan 24, 2026 Relationship Graphs and How ReBAC Checks Resolve Access How relationship tuples model authorization as graph traversal, why depth-bounded checks are the practical answer, and where cycles and fan-out break naive evaluation. security · intermediate
Jan 23, 2026 Compression and the Real Cost of an Ingested Byte Why group varint framing makes a serialized batch compact, which codecs suit which signal, and how ingest pricing turns bytes in the wrong place into a bill. observability · advanced
Jan 22, 2026 Bounded Clock Uncertainty and the Commit-Wait Rule How a clock that returns an interval instead of an instant lets a system order transactions by physical time, why reads must wait out the uncertainty, and what the wait costs. distributed systems · advanced
Jan 22, 2026 Evolving a Persistent Domain Model Without Downtime The expand-migrate-contract sequence, batched backfills, and event upcasting, for model changes that must survive mixed application versions and a rollback. software architecture · advanced
Jan 22, 2026 Fetch Event Interception and Response Construction How a service worker receives requests, what respondWith accepts, why a rejected promise produces an error page instead of a network fetch, and which requests never reach the handler. web platform · foundational
Jan 22, 2026 Nonce Construction and the Reuse Limits of AEAD Why an AEAD nonce must be unique per key, how counter, random, and XOR-based constructions differ in what they assume, and what a repeated nonce reveals. cryptography · intermediate
Jan 22, 2026 Safe States and Fail-Silent Behaviour in Control Systems How a safe state is chosen when no single output value is safe for every hazard, why de-energisation is the default, and what fail-silent units cost in availability. embedded systems · foundational
Jan 22, 2026 Sagas, Compensations, and the Semantics a Rollback Cannot Restore How long-running distributed transactions replace atomic rollback with forward recovery, why a compensation is not an inverse, and what the scheduler must guarantee to make it work. distributed systems · advanced
Jan 22, 2026 Warp Stall Reasons and Cycle Attribution How a profiler turns idle issue slots into named stall categories, what each category actually means at the scheduler, and how to read the breakdown without over-interpreting it. gpu computing · intermediate
Jan 21, 2026 Encoding Turing Machines and the Undecidability of Acceptance How a machine becomes a finite string, what a configuration record contains, and why diagonalization over that encoding rules out any decider for acceptance. computation theory · foundational
Jan 21, 2026 Fortune's Sweep and the Beach Line of Parabolic Arcs How a moving line and a growing chain of parabola arcs produce the Voronoi diagram in O(n log n), and why circle events are the subtle part. algorithms · intermediate
Jan 21, 2026 The Prefix Function and Linear-Time Exact Matching How the prefix function records the longest proper border of each pattern prefix, and why following failure links keeps total matching work linear in the text length. algorithms · foundational
Jan 20, 2026 Error Budgets and the Burn Rate That Consumes Them How an error budget turns a service level objective into a spendable quantity, and how the burn rate compresses a window into a single number that can be compared against a threshold. observability · foundational
Jan 20, 2026 Power-Loss Protection: What a Controller Must Persist, and When The in-flight state a flash controller holds in volatile memory, the energy budget that keeps it alive long enough to flush, and how recovery reconstructs a mapping table from torn pages. hardware engineering · advanced
Jan 20, 2026 Replaying a Queue Against State That Has Moved On When queued writes finally reach the server, the world may have changed beneath them; version vectors, field-level merge rules, and conflict surfacing decide what survives. mobile computing · intermediate
Jan 20, 2026 The Page Cache and the Writeback Path Where a written byte actually lives before it reaches the device, how dirty pages are tracked and flushed, and why write() returning does not mean the data is on disk. filesystems · intermediate
Jan 19, 2026 Embedding Layers as Learned Lookup Tables An embedding table is a matrix indexed by token id whose rows receive sparse gradients; its memory arithmetic, initialization, and weight tying decide what a model can learn from rare inputs. deep learning · foundational
Jan 19, 2026 Subnormals, Signed Zero, and the Cost of Gradual Underflow Why the exponent field needed two reserved encodings, what a subnormal costs in precision, and how signed zero and NaN payloads change the meaning of equality. scientific computing · foundational
Jan 19, 2026 What Makes a Safe Wrapper Around Unsafe Code Sound A safe function that can cause undefined behaviour from any call site destroys the guarantee for the entire crate graph, and the obligations that prevent it are structural rather than local. systems programming · intermediate
Jan 18, 2026 Link Aggregation and the Hash That Chooses a Member How LACP bundles links, why the distributor hashes rather than round-robins, and the ordering guarantee that constrains every possible choice. networking · advanced
Jan 18, 2026 Lockstep Cores and Comparator Logic in Safety Microcontrollers How two cores executing the same instruction stream are compared cycle by cycle, what a comparator can and cannot detect, and why the delay between the lanes is a deliberate design parameter. embedded systems · intermediate
Jan 18, 2026 Name Matching and Revocation: What the Certificate Does Not Tell You Subject alternative names, wildcard coverage, and the two revocation mechanisms, including why a stapled response and a fetched response answer different questions. internet protocols · intermediate
Jan 18, 2026 Rescaling Keyed State Without Replaying History Why changing an operator's parallelism redistributes state, how the key-group indirection makes the move a file copy, and what forces a full replay instead. data engineering · advanced
Jan 17, 2026 Comparison Lower Bounds From Decision Trees and Adversaries Counting distinguishable outcomes gives the n log n sorting bound. When that counting is not available, an adversary argument supplies the same conclusion by a different route. algorithms · intermediate
Jan 17, 2026 Hermetic Build Actions: Enforcing That Compilation Reads Only Declared Inputs A declared input list is a promise. Making the promise enforceable means restricting the file system, the clock, and the network, and choosing which of those restrictions is worth its cost. compilers · advanced

2026

January