Add method for per-CPU ring draining#294
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| hard_page_faults_builder: Option<RingBufBuilder<PageFaults>>, | ||
| next_time: Option<u64>, | ||
| oldest_cpu: Option<usize>, | ||
| cpu_reader_index: HashMap<u32, usize>, |
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Since we map index to CPU, lets just use a Vec here that expands to the amount of index's we have. This will speed up the lookup compared to a hash.
| self.enabled | ||
| } | ||
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| fn begin_reading_cpu( |
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It would be nice to have begin_reading_cpu() return a struct that contains the reader, cursor that then is passed to read_cpu(). This would eliminate several branches and memory lookups within read_cpu() that is called in a tight loop when on a per-CPU looping path.
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It could also contain a copy of the ancillary as well.
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Changes
Adds
parse_for_cpu(cpu)(Option 1 from #254) - drains and dispatches one CPU's ring, firing event callbacks likeparse_allbut scoped to a single CPU. This is the final piece of the wakeup-watermark work, completingwith_wakeup_watermark()(#276) andperf_fds()(#279).Motivation
A multi-CPU
PerfSessionregisters one perf fd per CPU with the consumer's event loop (epoll /AsyncFd). The readiness signal is per-CPU, butparse_alldrains every ring - so a wakeup on one CPU pulled events from CPUs whose watermark hadn't tripped.parse_for_cpumatches the drain to the signal: one fd fires, one ring drains.