67 lines
2.3 KiB
C
67 lines
2.3 KiB
C
#ifndef JEMALLOC_INTERNAL_DECAY_H
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#define JEMALLOC_INTERNAL_DECAY_H
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#include "jemalloc/internal/smoothstep.h"
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/*
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* The decay_t computes the number of pages we should purge at any given time.
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* Page allocators inform a decay object when pages enter a decay-able state
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* (i.e. dirty or muzzy), and query it to determine how many pages should be
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* purged at any given time.
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*/
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typedef struct decay_s decay_t;
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struct decay_s {
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/* Synchronizes all non-atomic fields. */
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malloc_mutex_t mtx;
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/*
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* True if a thread is currently purging the extents associated with
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* this decay structure.
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*/
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bool purging;
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/*
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* Approximate time in milliseconds from the creation of a set of unused
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* dirty pages until an equivalent set of unused dirty pages is purged
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* and/or reused.
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*/
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atomic_zd_t time_ms;
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/* time / SMOOTHSTEP_NSTEPS. */
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nstime_t interval;
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/*
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* Time at which the current decay interval logically started. We do
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* not actually advance to a new epoch until sometime after it starts
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* because of scheduling and computation delays, and it is even possible
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* to completely skip epochs. In all cases, during epoch advancement we
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* merge all relevant activity into the most recently recorded epoch.
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*/
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nstime_t epoch;
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/* Deadline randomness generator. */
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uint64_t jitter_state;
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/*
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* Deadline for current epoch. This is the sum of interval and per
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* epoch jitter which is a uniform random variable in [0..interval).
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* Epochs always advance by precise multiples of interval, but we
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* randomize the deadline to reduce the likelihood of arenas purging in
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* lockstep.
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*/
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nstime_t deadline;
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/*
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* Number of unpurged pages at beginning of current epoch. During epoch
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* advancement we use the delta between arena->decay_*.nunpurged and
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* ecache_npages_get(&arena->ecache_*) to determine how many dirty pages,
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* if any, were generated.
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*/
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size_t nunpurged;
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/*
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* Trailing log of how many unused dirty pages were generated during
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* each of the past SMOOTHSTEP_NSTEPS decay epochs, where the last
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* element is the most recent epoch. Corresponding epoch times are
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* relative to epoch.
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*/
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size_t backlog[SMOOTHSTEP_NSTEPS];
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/* Peak number of pages in associated extents. Used for debug only. */
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uint64_t ceil_npages;
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};
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#endif /* JEMALLOC_INTERNAL_DECAY_H */
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