At 4 KiB random reads on a 4 vCPU KVM guest with 4 virtio-blk queues, io_uring without SQPOLL tops out near 92k IOPS while –sqthread_poll=1 reaches about 118k – a…
Read MoreEd25519 vs RSA on a Small VPS: Where SSH Handshake CPU Actually Goes
A TLS 1.3 handshake with an Ed25519 certificate costs about 11 µs of CPU on a modern server core. RSA-2048 signing costs roughly 90 µs, plus 35 µs for the…
Read MoreInstrumenting nginx Request Timing to Find Where p99 Latency Actually Comes From
A slow page is rarely one slow thing. It is a sum of intervals: time queued in the accept backlog, time waiting for a free PHP-FPM worker, time spent in…
Read Morejemalloc Arena and Decay Tuning for Redis and nginx on Memory-Constrained Instances
Long-running daemons on small instances accumulate memory that the allocator never returns to the kernel. The process RSS climbs for days while the application’s own live heap stays flat, and…
Read MoreMTU and PMTUD Black Holes: Diagnosing the Stalls That Look Like TLS Failures
Most TLS failures that are not certificate errors are MTU problems wearing a disguise. The TCP handshake completes, the certificate verifies, the first small HTTP response arrives — and then…
Read MoreLowering DNS TTL Before a VPS Cutover: A Measured Rollback-Safe Procedure
A cutover fails in the rollback, not in the switch. The switch is one edit to an A record; the rollback is where you discover a resolver on the other…
Read MoreWireGuard Performance Tuning on a VPS: MTU, Multicore and Throughput Measurement
WireGuard is fast by default, but “fast by default” is not the same as “fast on your VPS”. A single-threaded tunnel on a small instance can saturate at a few…
Read Moredm-crypt and LUKS Encryption Overhead on a VPS: Measuring the Real Cost of AES-NI
Encrypting a VPS disk used to mean paying a heavy performance tax. With AES-NI hardware acceleration present, that tax is often under five percent for throughput and near zero for…
Read MoreCron vs systemd Timers: Measuring and Spreading Schedule Jitter on Small VPS Hosts
“Cron runs at the top of the minute” is the standard explanation for thundering-herd load spikes and missed maintenance windows, but on modern systemd hosts the real behaviour is subtler….
Read Morecgroups v2 on a VPS: Capping CPU, Memory and I/O per Service with systemd
A single runaway service — a rebuild, a backup, a memory leak — can starve everything else on a small VPS. cgroups v2 lets you bound each service’s CPU, memory…
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