On a KVM guest backed by a host-side NVMe device, the block layer still presents a scheduler and still has a queue depth, and both are frequently left at defaults…
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After the Free Tier Ends: Mapping the Month-by-Month Cost Curve of AWS, GCP, Oracle and Azure VPS Handovers
Free tiers are not free; they are a 12-month loan with a balloon payment attached. The interesting number is not what you pay in month one, it is what your…
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Verifying a VPS Network: iperf3 Throughput Tests, mtr Route Readings and Disk Floors
Every provider’s order page sells the same four numbers: vCPU count, RAM, disk size and port speed. Three of those four are measurable in under ten minutes with tools that…
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nftables Flowtables and Rule Counters: Measuring a Firewall That Costs Nothing at PPS Scale
A firewall that costs nothing per packet is not a marketing phrase, it is a measurable property of the datapath. A plain nftables ruleset with 40 rules in a chain…
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NUMA Locality Inside a KVM Guest: How to Measure the Remote-Memory Penalty
Remote memory access can cost 40-60% of local latency. Detect NUMA topology on large instances, place databases with numactl and cgroup cpusets, and verify with numastat.
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Reading /proc/net/softnet_stat Correctly: Diagnosing Softirq Pile-Up on Virtio NICs
Move packet processing off a single core: configure IRQ affinity, Receive Packet Steering, Transmit Packet Steering, and NAPI budget to cut softirq saturation on virtio NICs.
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