Activity of the ZFS ARC
Disk I/O is still a common source of performance issues, despite modern cloud environments, modern file systems and huge amounts of main memory serving as file system cache. Understanding how well that cache is working is a key task while investigating disk I/O issues. In this post, I’ll show the activity of the ZFS file [...]
In: Kernel · Tagged with: ARC, dtrace, performance, ZFS
Flame Graphs
MySQL Flame Graph Determining why CPUs are busy is a routine task for performance analysis, which often involves profiling stack traces. Profiling by sampling at a fixed rate is a coarse but effective way to see which code-paths are hot (busy on-CPU). It usually works by creating a timed interrupt that collects the current program [...]
In: Performance · Tagged with: dtrace, performance, profiling, visualizations
2000x performance win
I recently helped analyze a performance issue in an unexpected but common place, where the fix improved performance of a task by around 2000x (two thousand times faster). As this is short, interesting and useful, I’ve reproduced it here in a lab environment to share details and screenshots. Issue In a production SmartOS cloud environment, [...]
In: DTrace · Tagged with: dtrace, performance, smartos
