FOSDEM '08 is a free and non-commercial event organised by the community, for the community. Its goal is to provide Free and Open Source developers a place to meet.


Schedule: IOGrind: locating I/O performance problems

Michael Meeks
Day Saturday
Room Ferrer
Start time 15:00
End time 15:15
Duration 00:15
Event type Lightning-Talk
Track Lightning Talks
Language English
Slides (PDF)
Video (Ogg/Theora)
IOGrind: locating I/O performance problems

I/O latency is the dominating factor in desktop application startup performance. It is also one of the hardest things to measure in a reliable and deterministic fashion. Wall-clock timings on just-booted, quiescent systems give unfeasibly large jitter making optimising cold-start times extremely difficult.

Measures of warm vs. cold start show eg. 80% of an OO.o cold start is pure I/O time. I/O grind is a new valgrind based tool that can record & simulate I/O patterns, allowing not only targeted optimisation of applications, but deterministic comparisons of kernel I/O algorithms. Kernel optimisation is often focused on more tractable CPU cycles, however the big wins are in I/O behavior - saving only one seek on cold OO.o startup, is the equivalent of a 500 cycle win on every system call emitted.

IOGrind is a tool for locating I/O related performance problems, that hurt application cold-start times.