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b2d3d61adb
The interrupt framework gives a lot of information about each interrupt. It does not keep track of when those interrupts occur though, which is a prerequisite for estimating the next interrupt arrival for power management purposes. Add a mechanism to record the timestamp for each interrupt occurrences in a per-CPU circular buffer to help with the prediction of the next occurrence using a statistical model. Each CPU can store up to IRQ_TIMINGS_SIZE events <irq, timestamp>, the current value of IRQ_TIMINGS_SIZE is 32. Each event is encoded into a single u64, where the high 48 bits are used for the timestamp and the low 16 bits are for the irq number. A static key is introduced so when the irq prediction is switched off at runtime, the overhead is near to zero. It results in most of the code in internals.h for inline reasons and a very few in the new file timings.c. The latter will contain more in the next patch which will provide the statistical model for the next event prediction. Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Hannes Reinecke <hare@suse.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Cc: "Rafael J . Wysocki" <rafael@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Bjorn Helgaas <bhelgaas@google.com> Link: http://lkml.kernel.org/r/1498227072-5980-1-git-send-email-daniel.lezcano@linaro.org |
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| asm-generic | ||
| clocksource | ||
| crypto | ||
| drm | ||
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| keys | ||
| kvm | ||
| linux | ||
| math-emu | ||
| media | ||
| memory | ||
| misc | ||
| net | ||
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| soc | ||
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| target | ||
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| uapi | ||
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