Технические причины деградации производительности

Уровень 0 · материалов: 4

В кластер включаются документы с глубоким техническим анализом причин снижения производительности систем, но не общие руководства по оптимизации.

Общие признаки: анализ падения производительности, поиск первопричин системных сбоев, технический troubleshooting, влияние конфигураций ОС и ПО на CPU

Группа выше: Метрики производительности и их интерпретация

Материалы

• #24577 — Solving SQL Server Performance Issues on VMware — Представитель этого кластера

  Да мой старый laptop в несколько раз мощнее, чем ваш production server — Tzimie

  Смысл: The text illustrates a deep-dive technical troubleshooting process where a significant performance degradation in SQL Server on VMware was traced back to the overhead of virtualized Time Stamp Counter (TSC) synchronization across different physical CPU frequencies.

  SQL Server performance drops on VMware due to virtualized system time corrections after vMotion, solvable by disabling TSC virtualization.

• #18481 — Investigating CPU Utilization Growth during CentOS 7 to Oracle Linux 7 Migration

  Исследование роста утилизации процессора: как мы мигрировали с CentOS 7 на Oracle Linux 7 — juise

  Смысл: The main idea is that a perceived performance degradation (increased CPU usage) after a kernel migration was actually a result of more precise accounting of CPU ticks in the new kernel version due to the CONFIG_IRQ_TIME_ACCOUNTING setting.

  A reported 10% increase in CPU utilization after migrating to Oracle Linux 7 was discovered to be a reporting difference caused by the CONFIG_IRQ_TIME_ACCOUNTING kernel setting rather than an actual performance drop.

• #25389 — Investigating Chrome Freezes and CFG Memory Fragmentation

  24-ядерный CPU, а я не могу набрать электронное письмо — m1rko

  Смысл: The text illustrates how a complex interaction between a browser's JIT engine (V8), an OS security feature (CFG), and a third-party monitoring tool (WMI) can cause significant performance degradation and system freezes.

  A Google engineer discovered that Gmail's service workers caused CFG memory fragmentation in Windows, which led to browser freezes during scheduled IT memory scans.

• #8011 — Diagnosing High Server Load Caused by PHP Session Garbage Collection

  С какой проблемой мы столкнулись на виртуальном хостинге — homm

  Смысл: The text illustrates how a combination of misconfigured PHP session garbage collection settings and a cluttered system temporary directory on a shared hosting environment can lead to catastrophic server performance degradation and misleading CPU load metrics.

  A website experienced massive CPU spikes and intermittent crashes due to PHP's session garbage collection attempting to clean a bloated /tmp folder on a new virtual host server.