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Practical writing about software, systems, and the small details that make products feel solid.

01 / Latest

Fresh from the notebook

Tech 19 Sep 2026 4 min read

Write-Combining Device Memory Can Merge CPU Stores Before I/O

Write-Combining Device Memory Can Merge CPU Stores Before I/O A sequence of CPU stores to device memory does not necessarily become an identical sequence of bus transactions. With a write-combining mapping, the processor may collect adjacent stores and emit a larger transfer later. That behavior suits framebuffer-like regions and other device buffers built for bulk writes, but it changes the ordering and transaction assumptions a driver can safely make. Linux exposes this mapping class through interfaces such as ioremap_wc(). It is distinct from the default ioremap() mapping used for ordinary control registers.

MMIO Linux

Software Engineering 19 Sep 2026 6 min read

Write Skew Breaks Cross-Row Invariants Under Snapshot Isolation

Snapshot isolation can let two transactions commit even when their combined result violates a rule that each transaction checked before writing. The anomaly appears when both transactions read the same logical condition, then write different rows. Because their write sets do not overlap, ordinary write-write conflict detection has nothing to reject. This is write skew. It matters at the boundary between application invariants and database isolation: a transaction may see a consistent snapshot and still participate in a final state that would have failed its own predicate.

Software Engineering Database

Cloud Computing 19 Sep 2026 5 min read

Wildcard Subdomains on Cloudflare Workers: Routing and TLS Boundaries

A hostname such as demo.instara.app can reach a Cloudflare Worker through one wildcard DNS record and one Worker Route. A deeper hostname such as web.demo.instara.app can resolve through the same wildcard DNS record and still fail before the Worker runs because the edge certificate does not cover that hostname. That distinction matters because three independent mechanisms participate in the request: DNS resolution | v Worker Route matching | v TLS certificate coverage They all use wildcard syntax, but they do not have identical matching rules.

Cloud Computing Cloudflare Workers

Artificial Intelligence 19 Sep 2026 8 min read

Where PEGASUS-XSum Inference Time Goes

google/pegasus-xsum is a summarization checkpoint, not a compact text utility. Its latency follows directly from the work performed by a large Transformer encoder-decoder: first encode the source document, then run the decoder repeatedly until the summary is complete. On a CPU, the second phase is usually the part that makes a short output feel disproportionately expensive. The original PEGASUS work describes a Transformer encoder-decoder pretrained with Gap Sentences Generation and reports a 568M-parameter best model. The XSum checkpoint is fine-tuned for highly abstractive single-document summarization. That combination is useful when summary quality matters, but it also means inference has substantially more machinery than extracting a few source sentences or running a small classifier.

Artificial Intelligence Summarization

Tech 19 Sep 2026 5 min read

When a Transformer Surface Can Become an Electric-Shock Hazard

A transformer can have exposed metal around its core, frame, mounting hardware, or enclosure while carrying hazardous voltage on its windings. Those metal parts are not automatically live simply because the transformer is energized. Whether touching them can produce an electric shock depends on the transformer’s construction, insulation condition, protective earthing, and the electrical path between the person and the circuit. The important distinction is between a conductor intended to carry voltage and an accessible conductive part that should remain separated from it.

Transformer Electrical Safety

Tech 19 Sep 2026 7 min read

What Happens When a Charger Cannot Supply Enough Current

A charger’s current rating is a capacity limit, not a fixed amount of current that it forces into a device. A 5 V, 3 A supply does not continuously push 3 A into every connected load. The load draws current according to its circuitry, while the source must keep its output within specification up to the current it is designed to provide. The interesting case begins when the device would benefit from more power than the source can supply. Depending on the charger, cable, charging protocol, and device power-management circuit, the result can be slower charging, reduced input voltage, source shutdown, repeated reconnects, or battery discharge even while the charger remains connected.

Charging Power Supply

02 / Topics