Speaker
Description
What do we want?
- Better CPU isolation, in order to run time-sensitive tasks without interruption
What is (one of the things) preventing this?
- queue_work_on(isolated_cpu)
While working on those, an interesting parallel programming strategy was noticed:
- Use per-cpu structures with local_lock, when a remote CPU needs any action performed, use queue_work_on(target_cpu).
- Works great for rare remote-cpu interactions, but is terrible for CPU isolation
Previous works (Mel Gorman, 01b44456) propose the usage of per-cpu spinlocks instead. But aren't spinlocks expensive?
The objective of this presentation is to show a performance analysis done on per-cpu spinlocks, presenting base info such as:
- Cache coherence & contention: why spinlocks can be expensive
- How per-cpu spinlocks prevent most of this cost?- How does that impact isolated cpus ?
And then showing the numbers:
- How many clock cycles does per-cpu spinlocks actually cost?
- What else can we do to save more cycles, and how those impact performance?
- How much of the impact can be 'hidden' by OOO execution?
- What about contention?
- How does that compare with the current solution?
