// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2016, Linaro Ltd - Daniel Lezcano <daniel.lezcano@linaro.org>
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#define pr_fmt(fmt) "irq_timings: " fmt
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#include <linux/kernel.h>
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#include <linux/percpu.h>
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#include <linux/slab.h>
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#include <linux/static_key.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/idr.h>
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#include <linux/irq.h>
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#include <linux/math64.h>
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#include <linux/log2.h>
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#include <trace/events/irq.h>
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#include "internals.h"
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DEFINE_STATIC_KEY_FALSE(irq_timing_enabled);
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DEFINE_PER_CPU(struct irq_timings, irq_timings);
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static DEFINE_IDR(irqt_stats);
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void irq_timings_enable(void)
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{
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static_branch_enable(&irq_timing_enabled);
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}
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void irq_timings_disable(void)
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{
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static_branch_disable(&irq_timing_enabled);
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}
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/*
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* The main goal of this algorithm is to predict the next interrupt
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* occurrence on the current CPU.
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*
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* Currently, the interrupt timings are stored in a circular array
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* buffer every time there is an interrupt, as a tuple: the interrupt
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* number and the associated timestamp when the event occurred <irq,
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* timestamp>.
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*
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* For every interrupt occurring in a short period of time, we can
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* measure the elapsed time between the occurrences for the same
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* interrupt and we end up with a suite of intervals. The experience
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* showed the interrupts are often coming following a periodic
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* pattern.
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*
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* The objective of the algorithm is to find out this periodic pattern
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* in a fastest way and use its period to predict the next irq event.
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*
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* When the next interrupt event is requested, we are in the situation
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* where the interrupts are disabled and the circular buffer
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* containing the timings is filled with the events which happened
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* after the previous next-interrupt-event request.
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*
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* At this point, we read the circular buffer and we fill the irq
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* related statistics structure. After this step, the circular array
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* containing the timings is empty because all the values are
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* dispatched in their corresponding buffers.
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*
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* Now for each interrupt, we can predict the next event by using the
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* suffix array, log interval and exponential moving average
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*
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* 1. Suffix array
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*
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* Suffix array is an array of all the suffixes of a string. It is
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* widely used as a data structure for compression, text search, ...
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* For instance for the word 'banana', the suffixes will be: 'banana'
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* 'anana' 'nana' 'ana' 'na' 'a'
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*
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* Usually, the suffix array is sorted but for our purpose it is
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* not necessary and won't provide any improvement in the context of
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* the solved problem where we clearly define the boundaries of the
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* search by a max period and min period.
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*
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* The suffix array will build a suite of intervals of different
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* length and will look for the repetition of each suite. If the suite
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* is repeating then we have the period because it is the length of
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* the suite whatever its position in the buffer.
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*
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* 2. Log interval
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*
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* We saw the irq timings allow to compute the interval of the
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* occurrences for a specific interrupt. We can reasonibly assume the
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* longer is the interval, the higher is the error for the next event
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* and we can consider storing those interval values into an array
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* where each slot in the array correspond to an interval at the power
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* of 2 of the index. For example, index 12 will contain values
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* between 2^11 and 2^12.
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*
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* At the end we have an array of values where at each index defines a
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* [2^index - 1, 2 ^ index] interval values allowing to store a large
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* number of values inside a small array.
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*
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* For example, if we have the value 1123, then we store it at
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* ilog2(1123) = 10 index value.
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*
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* Storing those value at the specific index is done by computing an
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* exponential moving average for this specific slot. For instance,
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* for values 1800, 1123, 1453, ... fall under the same slot (10) and
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* the exponential moving average is computed every time a new value
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* is stored at this slot.
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*
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* 3. Exponential Moving Average
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*
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* The EMA is largely used to track a signal for stocks or as a low
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* pass filter. The magic of the formula, is it is very simple and the
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* reactivity of the average can be tuned with the factors called
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* alpha.
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*
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* The higher the alphas are, the faster the average respond to the
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* signal change. In our case, if a slot in the array is a big
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* interval, we can have numbers with a big difference between
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* them. The impact of those differences in the average computation
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* can be tuned by changing the alpha value.
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*
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*
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* -- The algorithm --
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*
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* We saw the different processing above, now let's see how they are
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* used together.
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*
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* For each interrupt:
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* For each interval:
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* Compute the index = ilog2(interval)
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* Compute a new_ema(buffer[index], interval)
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* Store the index in a circular buffer
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*
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* Compute the suffix array of the indexes
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*
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* For each suffix:
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* If the suffix is reverse-found 3 times
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* Return suffix
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*
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* Return Not found
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*
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* However we can not have endless suffix array to be build, it won't
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* make sense and it will add an extra overhead, so we can restrict
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* this to a maximum suffix length of 5 and a minimum suffix length of
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* 2. The experience showed 5 is the majority of the maximum pattern
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* period found for different devices.
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*
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* The result is a pattern finding less than 1us for an interrupt.
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*
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* Example based on real values:
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*
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* Example 1 : MMC write/read interrupt interval:
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*
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* 223947, 1240, 1384, 1386, 1386,
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* 217416, 1236, 1384, 1386, 1387,
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* 214719, 1241, 1386, 1387, 1384,
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* 213696, 1234, 1384, 1386, 1388,
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* 219904, 1240, 1385, 1389, 1385,
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* 212240, 1240, 1386, 1386, 1386,
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* 214415, 1236, 1384, 1386, 1387,
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* 214276, 1234, 1384, 1388, ?
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*
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* For each element, apply ilog2(value)
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*
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, ?
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*
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* Max period of 5, we take the last (max_period * 3) 15 elements as
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* we can be confident if the pattern repeats itself three times it is
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* a repeating pattern.
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*
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* 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, 8,
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* 15, 8, 8, 8, ?
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*
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* Suffixes are:
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*
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* 1) 8, 15, 8, 8, 8 <- max period
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* 2) 8, 15, 8, 8
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* 3) 8, 15, 8
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* 4) 8, 15 <- min period
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*
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* From there we search the repeating pattern for each suffix.
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*
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* buffer: 8, 15, 8, 8, 8, 8, 15, 8, 8, 8, 8, 15, 8, 8, 8
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* | | | | | | | | | | | | | | |
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* 8, 15, 8, 8, 8 | | | | | | | | | |
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* 8, 15, 8, 8, 8 | | | | |
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* 8, 15, 8, 8, 8
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*
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* When moving the suffix, we found exactly 3 matches.
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*
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* The first suffix with period 5 is repeating.
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*
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* The next event is (3 * max_period) % suffix_period
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*
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* In this example, the result 0, so the next event is suffix[0] => 8
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*
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* However, 8 is the index in the array of exponential moving average
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* which was calculated on the fly when storing the values, so the
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* interval is ema[8] = 1366
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*
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*
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* Example 2:
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*
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* 4, 3, 5, 100,
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* 3, 3, 5, 117,
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* 4, 4, 5, 112,
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* 4, 3, 4, 110,
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* 3, 5, 3, 117,
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* 4, 4, 5, 112,
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* 4, 3, 4, 110,
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* 3, 4, 5, 112,
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* 4, 3, 4, 110
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*
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* ilog2
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*
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4
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*
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* Max period 5:
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* 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4,
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* 0, 0, 0, 4
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*
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* Suffixes:
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*
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* 1) 0, 0, 4, 0, 0
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* 2) 0, 0, 4, 0
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* 3) 0, 0, 4
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* 4) 0, 0
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*
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* buffer: 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 4
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* | | | | | | X
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* 0, 0, 4, 0, 0, | X
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* 0, 0
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*
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* buffer: 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 4, 0, 0, 0, 4
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* | | | | | | | | | | | | | | |
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* 0, 0, 4, 0, | | | | | | | | | | |
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* 0, 0, 4, 0, | | | | | | |
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* 0, 0, 4, 0, | | |
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* 0 0 4
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*
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* Pattern is found 3 times, the remaining is 1 which results from
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* (max_period * 3) % suffix_period. This value is the index in the
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* suffix arrays. The suffix array for a period 4 has the value 4
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* at index 1.
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*/
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#define EMA_ALPHA_VAL 64
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#define EMA_ALPHA_SHIFT 7
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#define PREDICTION_PERIOD_MIN 3
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#define PREDICTION_PERIOD_MAX 5
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#define PREDICTION_FACTOR 4
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#define PREDICTION_MAX 10 /* 2 ^ PREDICTION_MAX useconds */
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#define PREDICTION_BUFFER_SIZE 16 /* slots for EMAs, hardly more than 16 */
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/*
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* Number of elements in the circular buffer: If it happens it was
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* flushed before, then the number of elements could be smaller than
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* IRQ_TIMINGS_SIZE, so the count is used, otherwise the array size is
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* used as we wrapped. The index begins from zero when we did not
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* wrap. That could be done in a nicer way with the proper circular
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* array structure type but with the cost of extra computation in the
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* interrupt handler hot path. We choose efficiency.
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*/
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#define for_each_irqts(i, irqts) \
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for (i = irqts->count < IRQ_TIMINGS_SIZE ? \
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0 : irqts->count & IRQ_TIMINGS_MASK, \
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irqts->count = min(IRQ_TIMINGS_SIZE, \
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irqts->count); \
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irqts->count > 0; irqts->count--, \
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i = (i + 1) & IRQ_TIMINGS_MASK)
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struct irqt_stat {
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u64 last_ts;
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u64 ema_time[PREDICTION_BUFFER_SIZE];
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int timings[IRQ_TIMINGS_SIZE];
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int circ_timings[IRQ_TIMINGS_SIZE];
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int count;
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};
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/*
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* Exponential moving average computation
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*/
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static u64 irq_timings_ema_new(u64 value, u64 ema_old)
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{
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s64 diff;
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if (unlikely(!ema_old))
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return value;
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diff = (value - ema_old) * EMA_ALPHA_VAL;
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/*
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* We can use a s64 type variable to be added with the u64
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* ema_old variable as this one will never have its topmost
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* bit set, it will be always smaller than 2^63 nanosec
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* interrupt interval (292 years).
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*/
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return ema_old + (diff >> EMA_ALPHA_SHIFT);
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}
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static int irq_timings_next_event_index(int *buffer, size_t len, int period_max)
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{
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int period;
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/*
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* Move the beginning pointer to the end minus the max period x 3.
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* We are at the point we can begin searching the pattern
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*/
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buffer = &buffer[len - (period_max * 3)];
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/* Adjust the length to the maximum allowed period x 3 */
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len = period_max * 3;
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/*
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* The buffer contains the suite of intervals, in a ilog2
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* basis, we are looking for a repetition. We point the
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* beginning of the search three times the length of the
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* period beginning at the end of the buffer. We do that for
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* each suffix.
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*/
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for (period = period_max; period >= PREDICTION_PERIOD_MIN; period--) {
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/*
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* The first comparison always succeed because the
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* suffix is deduced from the first n-period bytes of
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* the buffer and we compare the initial suffix with
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* itself, so we can skip the first iteration.
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*/
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int idx = period;
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size_t size = period;
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/*
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* We look if the suite with period 'i' repeat
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* itself. If it is truncated at the end, as it
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* repeats we can use the period to find out the next
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* element with the modulo.
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*/
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while (!memcmp(buffer, &buffer[idx], size * sizeof(int))) {
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/*
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* Move the index in a period basis
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*/
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idx += size;
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/*
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* If this condition is reached, all previous
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* memcmp were successful, so the period is
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* found.
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*/
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if (idx == len)
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return buffer[len % period];
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/*
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* If the remaining elements to compare are
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* smaller than the period, readjust the size
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* of the comparison for the last iteration.
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*/
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if (len - idx < period)
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size = len - idx;
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}
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}
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return -1;
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}
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static u64 __irq_timings_next_event(struct irqt_stat *irqs, int irq, u64 now)
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{
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int index, i, period_max, count, start, min = INT_MAX;
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if ((now - irqs->last_ts) >= NSEC_PER_SEC) {
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irqs->count = irqs->last_ts = 0;
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return U64_MAX;
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}
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/*
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* As we want to find three times the repetition, we need a
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* number of intervals greater or equal to three times the
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* maximum period, otherwise we truncate the max period.
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*/
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period_max = irqs->count > (3 * PREDICTION_PERIOD_MAX) ?
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PREDICTION_PERIOD_MAX : irqs->count / 3;
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/*
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* If we don't have enough irq timings for this prediction,
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* just bail out.
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*/
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if (period_max <= PREDICTION_PERIOD_MIN)
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return U64_MAX;
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/*
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* 'count' will depends if the circular buffer wrapped or not
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*/
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count = irqs->count < IRQ_TIMINGS_SIZE ?
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irqs->count : IRQ_TIMINGS_SIZE;
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start = irqs->count < IRQ_TIMINGS_SIZE ?
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0 : (irqs->count & IRQ_TIMINGS_MASK);
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/*
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* Copy the content of the circular buffer into another buffer
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* in order to linearize the buffer instead of dealing with
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* wrapping indexes and shifted array which will be prone to
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* error and extremelly difficult to debug.
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*/
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for (i = 0; i < count; i++) {
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int index = (start + i) & IRQ_TIMINGS_MASK;
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irqs->timings[i] = irqs->circ_timings[index];
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min = min_t(int, irqs->timings[i], min);
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}
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index = irq_timings_next_event_index(irqs->timings, count, period_max);
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if (index < 0)
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return irqs->last_ts + irqs->ema_time[min];
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return irqs->last_ts + irqs->ema_time[index];
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}
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static __always_inline int irq_timings_interval_index(u64 interval)
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{
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/*
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* The PREDICTION_FACTOR increase the interval size for the
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* array of exponential average.
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*/
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u64 interval_us = (interval >> 10) / PREDICTION_FACTOR;
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return likely(interval_us) ? ilog2(interval_us) : 0;
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}
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static __always_inline void __irq_timings_store(int irq, struct irqt_stat *irqs,
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u64 interval)
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{
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int index;
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/*
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* Get the index in the ema table for this interrupt.
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*/
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index = irq_timings_interval_index(interval);
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if (index > PREDICTION_BUFFER_SIZE - 1) {
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irqs->count = 0;
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return;
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}
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/*
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* Store the index as an element of the pattern in another
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* circular array.
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*/
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irqs->circ_timings[irqs->count & IRQ_TIMINGS_MASK] = index;
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irqs->ema_time[index] = irq_timings_ema_new(interval,
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irqs->ema_time[index]);
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irqs->count++;
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}
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static inline void irq_timings_store(int irq, struct irqt_stat *irqs, u64 ts)
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{
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u64 old_ts = irqs->last_ts;
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u64 interval;
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/*
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* The timestamps are absolute time values, we need to compute
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* the timing interval between two interrupts.
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*/
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irqs->last_ts = ts;
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/*
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* The interval type is u64 in order to deal with the same
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* type in our computation, that prevent mindfuck issues with
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* overflow, sign and division.
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*/
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interval = ts - old_ts;
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/*
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* The interrupt triggered more than one second apart, that
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* ends the sequence as predictible for our purpose. In this
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* case, assume we have the beginning of a sequence and the
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* timestamp is the first value. As it is impossible to
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* predict anything at this point, return.
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*
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* Note the first timestamp of the sequence will always fall
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* in this test because the old_ts is zero. That is what we
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* want as we need another timestamp to compute an interval.
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*/
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if (interval >= NSEC_PER_SEC) {
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irqs->count = 0;
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return;
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}
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__irq_timings_store(irq, irqs, interval);
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}
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/**
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* irq_timings_next_event - Return when the next event is supposed to arrive
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*
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* During the last busy cycle, the number of interrupts is incremented
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* and stored in the irq_timings structure. This information is
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* necessary to:
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*
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* - know if the index in the table wrapped up:
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*
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* If more than the array size interrupts happened during the
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* last busy/idle cycle, the index wrapped up and we have to
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* begin with the next element in the array which is the last one
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* in the sequence, otherwise it is a the index 0.
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*
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* - have an indication of the interrupts activity on this CPU
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* (eg. irq/sec)
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*
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* The values are 'consumed' after inserting in the statistical model,
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* thus the count is reinitialized.
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*
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* The array of values **must** be browsed in the time direction, the
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* timestamp must increase between an element and the next one.
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*
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* Returns a nanosec time based estimation of the earliest interrupt,
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* U64_MAX otherwise.
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*/
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u64 irq_timings_next_event(u64 now)
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{
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struct irq_timings *irqts = this_cpu_ptr(&irq_timings);
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struct irqt_stat *irqs;
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struct irqt_stat __percpu *s;
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u64 ts, next_evt = U64_MAX;
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int i, irq = 0;
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/*
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* This function must be called with the local irq disabled in
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* order to prevent the timings circular buffer to be updated
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* while we are reading it.
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*/
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lockdep_assert_irqs_disabled();
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if (!irqts->count)
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return next_evt;
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/*
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* Number of elements in the circular buffer: If it happens it
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* was flushed before, then the number of elements could be
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* smaller than IRQ_TIMINGS_SIZE, so the count is used,
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* otherwise the array size is used as we wrapped. The index
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* begins from zero when we did not wrap. That could be done
|
* in a nicer way with the proper circular array structure
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* type but with the cost of extra computation in the
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* interrupt handler hot path. We choose efficiency.
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*
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* Inject measured irq/timestamp to the pattern prediction
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* model while decrementing the counter because we consume the
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* data from our circular buffer.
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*/
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for_each_irqts(i, irqts) {
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irq = irq_timing_decode(irqts->values[i], &ts);
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s = idr_find(&irqt_stats, irq);
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if (s)
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irq_timings_store(irq, this_cpu_ptr(s), ts);
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}
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/*
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* Look in the list of interrupts' statistics, the earliest
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* next event.
|
*/
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idr_for_each_entry(&irqt_stats, s, i) {
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irqs = this_cpu_ptr(s);
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ts = __irq_timings_next_event(irqs, i, now);
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if (ts <= now)
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return now;
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if (ts < next_evt)
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next_evt = ts;
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}
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return next_evt;
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}
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void irq_timings_free(int irq)
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{
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struct irqt_stat __percpu *s;
|
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s = idr_find(&irqt_stats, irq);
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if (s) {
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free_percpu(s);
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idr_remove(&irqt_stats, irq);
|
}
|
}
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int irq_timings_alloc(int irq)
|
{
|
struct irqt_stat __percpu *s;
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int id;
|
|
/*
|
* Some platforms can have the same private interrupt per cpu,
|
* so this function may be called several times with the
|
* same interrupt number. Just bail out in case the per cpu
|
* stat structure is already allocated.
|
*/
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s = idr_find(&irqt_stats, irq);
|
if (s)
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return 0;
|
|
s = alloc_percpu(*s);
|
if (!s)
|
return -ENOMEM;
|
|
idr_preload(GFP_KERNEL);
|
id = idr_alloc(&irqt_stats, s, irq, irq + 1, GFP_NOWAIT);
|
idr_preload_end();
|
|
if (id < 0) {
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free_percpu(s);
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return id;
|
}
|
|
return 0;
|
}
|
|
#ifdef CONFIG_TEST_IRQ_TIMINGS
|
struct timings_intervals {
|
u64 *intervals;
|
size_t count;
|
};
|
|
/*
|
* Intervals are given in nanosecond base
|
*/
|
static u64 intervals0[] __initdata = {
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000, 500000,
|
10000, 50000, 200000,
|
};
|
|
static u64 intervals1[] __initdata = {
|
223947000, 1240000, 1384000, 1386000, 1386000,
|
217416000, 1236000, 1384000, 1386000, 1387000,
|
214719000, 1241000, 1386000, 1387000, 1384000,
|
213696000, 1234000, 1384000, 1386000, 1388000,
|
219904000, 1240000, 1385000, 1389000, 1385000,
|
212240000, 1240000, 1386000, 1386000, 1386000,
|
214415000, 1236000, 1384000, 1386000, 1387000,
|
214276000, 1234000,
|
};
|
|
static u64 intervals2[] __initdata = {
|
4000, 3000, 5000, 100000,
|
3000, 3000, 5000, 117000,
|
4000, 4000, 5000, 112000,
|
4000, 3000, 4000, 110000,
|
3000, 5000, 3000, 117000,
|
4000, 4000, 5000, 112000,
|
4000, 3000, 4000, 110000,
|
3000, 4000, 5000, 112000,
|
4000,
|
};
|
|
static u64 intervals3[] __initdata = {
|
1385000, 212240000, 1240000,
|
1386000, 214415000, 1236000,
|
1384000, 214276000, 1234000,
|
1386000, 214415000, 1236000,
|
1385000, 212240000, 1240000,
|
1386000, 214415000, 1236000,
|
1384000, 214276000, 1234000,
|
1386000, 214415000, 1236000,
|
1385000, 212240000, 1240000,
|
};
|
|
static u64 intervals4[] __initdata = {
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000, 50000, 10000, 50000,
|
10000,
|
};
|
|
static struct timings_intervals tis[] __initdata = {
|
{ intervals0, ARRAY_SIZE(intervals0) },
|
{ intervals1, ARRAY_SIZE(intervals1) },
|
{ intervals2, ARRAY_SIZE(intervals2) },
|
{ intervals3, ARRAY_SIZE(intervals3) },
|
{ intervals4, ARRAY_SIZE(intervals4) },
|
};
|
|
static int __init irq_timings_test_next_index(struct timings_intervals *ti)
|
{
|
int _buffer[IRQ_TIMINGS_SIZE];
|
int buffer[IRQ_TIMINGS_SIZE];
|
int index, start, i, count, period_max;
|
|
count = ti->count - 1;
|
|
period_max = count > (3 * PREDICTION_PERIOD_MAX) ?
|
PREDICTION_PERIOD_MAX : count / 3;
|
|
/*
|
* Inject all values except the last one which will be used
|
* to compare with the next index result.
|
*/
|
pr_debug("index suite: ");
|
|
for (i = 0; i < count; i++) {
|
index = irq_timings_interval_index(ti->intervals[i]);
|
_buffer[i & IRQ_TIMINGS_MASK] = index;
|
pr_cont("%d ", index);
|
}
|
|
start = count < IRQ_TIMINGS_SIZE ? 0 :
|
count & IRQ_TIMINGS_MASK;
|
|
count = min_t(int, count, IRQ_TIMINGS_SIZE);
|
|
for (i = 0; i < count; i++) {
|
int index = (start + i) & IRQ_TIMINGS_MASK;
|
buffer[i] = _buffer[index];
|
}
|
|
index = irq_timings_next_event_index(buffer, count, period_max);
|
i = irq_timings_interval_index(ti->intervals[ti->count - 1]);
|
|
if (index != i) {
|
pr_err("Expected (%d) and computed (%d) next indexes differ\n",
|
i, index);
|
return -EINVAL;
|
}
|
|
return 0;
|
}
|
|
static int __init irq_timings_next_index_selftest(void)
|
{
|
int i, ret;
|
|
for (i = 0; i < ARRAY_SIZE(tis); i++) {
|
|
pr_info("---> Injecting intervals number #%d (count=%zd)\n",
|
i, tis[i].count);
|
|
ret = irq_timings_test_next_index(&tis[i]);
|
if (ret)
|
break;
|
}
|
|
return ret;
|
}
|
|
static int __init irq_timings_test_irqs(struct timings_intervals *ti)
|
{
|
struct irqt_stat __percpu *s;
|
struct irqt_stat *irqs;
|
int i, index, ret, irq = 0xACE5;
|
|
ret = irq_timings_alloc(irq);
|
if (ret) {
|
pr_err("Failed to allocate irq timings\n");
|
return ret;
|
}
|
|
s = idr_find(&irqt_stats, irq);
|
if (!s) {
|
ret = -EIDRM;
|
goto out;
|
}
|
|
irqs = this_cpu_ptr(s);
|
|
for (i = 0; i < ti->count; i++) {
|
|
index = irq_timings_interval_index(ti->intervals[i]);
|
pr_debug("%d: interval=%llu ema_index=%d\n",
|
i, ti->intervals[i], index);
|
|
__irq_timings_store(irq, irqs, ti->intervals[i]);
|
if (irqs->circ_timings[i & IRQ_TIMINGS_MASK] != index) {
|
ret = -EBADSLT;
|
pr_err("Failed to store in the circular buffer\n");
|
goto out;
|
}
|
}
|
|
if (irqs->count != ti->count) {
|
ret = -ERANGE;
|
pr_err("Count differs\n");
|
goto out;
|
}
|
|
ret = 0;
|
out:
|
irq_timings_free(irq);
|
|
return ret;
|
}
|
|
static int __init irq_timings_irqs_selftest(void)
|
{
|
int i, ret;
|
|
for (i = 0; i < ARRAY_SIZE(tis); i++) {
|
pr_info("---> Injecting intervals number #%d (count=%zd)\n",
|
i, tis[i].count);
|
ret = irq_timings_test_irqs(&tis[i]);
|
if (ret)
|
break;
|
}
|
|
return ret;
|
}
|
|
static int __init irq_timings_test_irqts(struct irq_timings *irqts,
|
unsigned count)
|
{
|
int start = count >= IRQ_TIMINGS_SIZE ? count - IRQ_TIMINGS_SIZE : 0;
|
int i, irq, oirq = 0xBEEF;
|
u64 ots = 0xDEAD, ts;
|
|
/*
|
* Fill the circular buffer by using the dedicated function.
|
*/
|
for (i = 0; i < count; i++) {
|
pr_debug("%d: index=%d, ts=%llX irq=%X\n",
|
i, i & IRQ_TIMINGS_MASK, ots + i, oirq + i);
|
|
irq_timings_push(ots + i, oirq + i);
|
}
|
|
/*
|
* Compute the first elements values after the index wrapped
|
* up or not.
|
*/
|
ots += start;
|
oirq += start;
|
|
/*
|
* Test the circular buffer count is correct.
|
*/
|
pr_debug("---> Checking timings array count (%d) is right\n", count);
|
if (WARN_ON(irqts->count != count))
|
return -EINVAL;
|
|
/*
|
* Test the macro allowing to browse all the irqts.
|
*/
|
pr_debug("---> Checking the for_each_irqts() macro\n");
|
for_each_irqts(i, irqts) {
|
|
irq = irq_timing_decode(irqts->values[i], &ts);
|
|
pr_debug("index=%d, ts=%llX / %llX, irq=%X / %X\n",
|
i, ts, ots, irq, oirq);
|
|
if (WARN_ON(ts != ots || irq != oirq))
|
return -EINVAL;
|
|
ots++; oirq++;
|
}
|
|
/*
|
* The circular buffer should have be flushed when browsed
|
* with for_each_irqts
|
*/
|
pr_debug("---> Checking timings array is empty after browsing it\n");
|
if (WARN_ON(irqts->count))
|
return -EINVAL;
|
|
return 0;
|
}
|
|
static int __init irq_timings_irqts_selftest(void)
|
{
|
struct irq_timings *irqts = this_cpu_ptr(&irq_timings);
|
int i, ret;
|
|
/*
|
* Test the circular buffer with different number of
|
* elements. The purpose is to test at the limits (empty, half
|
* full, full, wrapped with the cursor at the boundaries,
|
* wrapped several times, etc ...
|
*/
|
int count[] = { 0,
|
IRQ_TIMINGS_SIZE >> 1,
|
IRQ_TIMINGS_SIZE,
|
IRQ_TIMINGS_SIZE + (IRQ_TIMINGS_SIZE >> 1),
|
2 * IRQ_TIMINGS_SIZE,
|
(2 * IRQ_TIMINGS_SIZE) + 3,
|
};
|
|
for (i = 0; i < ARRAY_SIZE(count); i++) {
|
|
pr_info("---> Checking the timings with %d/%d values\n",
|
count[i], IRQ_TIMINGS_SIZE);
|
|
ret = irq_timings_test_irqts(irqts, count[i]);
|
if (ret)
|
break;
|
}
|
|
return ret;
|
}
|
|
static int __init irq_timings_selftest(void)
|
{
|
int ret;
|
|
pr_info("------------------- selftest start -----------------\n");
|
|
/*
|
* At this point, we don't except any subsystem to use the irq
|
* timings but us, so it should not be enabled.
|
*/
|
if (static_branch_unlikely(&irq_timing_enabled)) {
|
pr_warn("irq timings already initialized, skipping selftest\n");
|
return 0;
|
}
|
|
ret = irq_timings_irqts_selftest();
|
if (ret)
|
goto out;
|
|
ret = irq_timings_irqs_selftest();
|
if (ret)
|
goto out;
|
|
ret = irq_timings_next_index_selftest();
|
out:
|
pr_info("---------- selftest end with %s -----------\n",
|
ret ? "failure" : "success");
|
|
return ret;
|
}
|
early_initcall(irq_timings_selftest);
|
#endif
|
