Use time based periods to age the writeback proportions,
which can adapt equally well to fast/slow devices. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAABAgAGBQJQF0/wAAoJECvKgwp+S8JaszsP/16EO5F5mUCOFgncVRp+8R9U BxuKJ61j2R9ckHA+ngMEg72W5vJQds64cjywZnz6HMr0/+3tXUf4QBbU4/4sCeai 0lpK8MCKgp5KHHCxgO8zyoSaboankUgoDcbSmGJREV1WXoR8VWXsO9gXqiiH9XOe e8ADjds/YdxkQbOYDRgZKvLzwWS61K9Kwq5/56GASh2uflw7rkJZ38xqvGbo3YiQ IJJwOUYfJjFadIewYARQmkZZyWeAmtY0ADh15Z8pJt+iY4PgcDDlaWagwUH2Oaoi vhTFO4KnCjhSpc872et21g/jN/VrcQqzuUF/LUE9rW5irXeDZVCDrCQOuHQ+3Uo5 YuV3rpNABW/LU8AvtIwt9hUunaKUnrXaSluoL9LzH2VpH++JljQeR4yZ62Q5rpRs z4Bow25p7tlbcIJWzueMPdOFUr5s3P6XfQHoLVRWqN94eJ+Z1DPOgBlOain6cCUN oivPh4FxZfUscNmX8/7cHaTNEpGzJ0FzLPMNFnGQ2zwG0gk41fnMdWb19aVIE5GL /Q96TB24k/v+o1lbxGmyPi0L+Aq+NknvNm+p/YJHAAQrIpu5t2hPvka8/m7Nj7tu c3rM75RKiZkEI+3U6Ws1DhhQPtVcfNIVlNYQMGzlIndtK6T0ByueQ4eN5Z7ltjSE pS89rv2hyBw7yCaTU6ui =gZrM -----END PGP SIGNATURE----- Merge tag 'writeback-proportions' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux Pull writeback updates from Wu Fengguang: "Use time based periods to age the writeback proportions, which can adapt equally well to fast/slow devices." Fix up trivial conflict in comment in fs/sync.c * tag 'writeback-proportions' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux: writeback: Fix some comment errors block: Convert BDI proportion calculations to flexible proportions lib: Fix possible deadlock in flexible proportion code lib: Proportions with flexible period
This commit is contained in:
Linus Torvalds
commit
2e3ee61348
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@ -628,8 +628,8 @@ static long writeback_sb_inodes(struct super_block *sb,
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}
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/*
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* Don't bother with new inodes or inodes beeing freed, first
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* kind does not need peridic writeout yet, and for the latter
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* Don't bother with new inodes or inodes being freed, first
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* kind does not need periodic writeout yet, and for the latter
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* kind writeout is handled by the freer.
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*/
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spin_lock(&inode->i_lock);
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@ -320,7 +320,7 @@ static int grab_super(struct super_block *s) __releases(sb_lock)
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/*
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* grab_super_passive - acquire a passive reference
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* @s: reference we are trying to grab
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* @sb: reference we are trying to grab
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*
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* Tries to acquire a passive reference. This is used in places where we
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* cannot take an active reference but we need to ensure that the
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@ -10,7 +10,7 @@
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#include <linux/percpu_counter.h>
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#include <linux/log2.h>
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#include <linux/proportions.h>
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#include <linux/flex_proportions.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/sched.h>
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@ -89,7 +89,7 @@ struct backing_dev_info {
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unsigned long dirty_ratelimit;
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unsigned long balanced_dirty_ratelimit;
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struct prop_local_percpu completions;
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struct fprop_local_percpu completions;
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int dirty_exceeded;
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unsigned int min_ratio;
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@ -0,0 +1,101 @@
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/*
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* Floating proportions with flexible aging period
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*
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* Copyright (C) 2011, SUSE, Jan Kara <jack@suse.cz>
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*/
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#ifndef _LINUX_FLEX_PROPORTIONS_H
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#define _LINUX_FLEX_PROPORTIONS_H
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#include <linux/percpu_counter.h>
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#include <linux/spinlock.h>
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#include <linux/seqlock.h>
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/*
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* When maximum proportion of some event type is specified, this is the
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* precision with which we allow limitting. Note that this creates an upper
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* bound on the number of events per period like
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* ULLONG_MAX >> FPROP_FRAC_SHIFT.
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*/
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#define FPROP_FRAC_SHIFT 10
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#define FPROP_FRAC_BASE (1UL << FPROP_FRAC_SHIFT)
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/*
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* ---- Global proportion definitions ----
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*/
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struct fprop_global {
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/* Number of events in the current period */
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struct percpu_counter events;
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/* Current period */
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unsigned int period;
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/* Synchronization with period transitions */
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seqcount_t sequence;
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};
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int fprop_global_init(struct fprop_global *p);
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void fprop_global_destroy(struct fprop_global *p);
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bool fprop_new_period(struct fprop_global *p, int periods);
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/*
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* ---- SINGLE ----
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*/
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struct fprop_local_single {
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/* the local events counter */
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unsigned long events;
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/* Period in which we last updated events */
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unsigned int period;
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raw_spinlock_t lock; /* Protect period and numerator */
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};
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#define INIT_FPROP_LOCAL_SINGLE(name) \
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{ .lock = __RAW_SPIN_LOCK_UNLOCKED(name.lock), \
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}
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int fprop_local_init_single(struct fprop_local_single *pl);
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void fprop_local_destroy_single(struct fprop_local_single *pl);
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void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl);
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void fprop_fraction_single(struct fprop_global *p,
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struct fprop_local_single *pl, unsigned long *numerator,
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unsigned long *denominator);
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static inline
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void fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl)
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{
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unsigned long flags;
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local_irq_save(flags);
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__fprop_inc_single(p, pl);
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local_irq_restore(flags);
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}
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/*
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* ---- PERCPU ----
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*/
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struct fprop_local_percpu {
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/* the local events counter */
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struct percpu_counter events;
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/* Period in which we last updated events */
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unsigned int period;
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raw_spinlock_t lock; /* Protect period and numerator */
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};
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int fprop_local_init_percpu(struct fprop_local_percpu *pl);
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void fprop_local_destroy_percpu(struct fprop_local_percpu *pl);
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void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl);
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void __fprop_inc_percpu_max(struct fprop_global *p, struct fprop_local_percpu *pl,
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int max_frac);
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void fprop_fraction_percpu(struct fprop_global *p,
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struct fprop_local_percpu *pl, unsigned long *numerator,
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unsigned long *denominator);
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static inline
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void fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
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{
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unsigned long flags;
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local_irq_save(flags);
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__fprop_inc_percpu(p, pl);
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local_irq_restore(flags);
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}
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#endif
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@ -11,7 +11,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
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rbtree.o radix-tree.o dump_stack.o timerqueue.o\
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idr.o int_sqrt.o extable.o prio_tree.o \
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sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
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proportions.o prio_heap.o ratelimit.o show_mem.o \
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proportions.o flex_proportions.o prio_heap.o ratelimit.o show_mem.o \
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is_single_threaded.o plist.o decompress.o
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lib-$(CONFIG_MMU) += ioremap.o
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@ -0,0 +1,272 @@
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/*
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* Floating proportions with flexible aging period
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*
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* Copyright (C) 2011, SUSE, Jan Kara <jack@suse.cz>
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*
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* The goal of this code is: Given different types of event, measure proportion
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* of each type of event over time. The proportions are measured with
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* exponentially decaying history to give smooth transitions. A formula
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* expressing proportion of event of type 'j' is:
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*
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* p_{j} = (\Sum_{i>=0} x_{i,j}/2^{i+1})/(\Sum_{i>=0} x_i/2^{i+1})
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*
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* Where x_{i,j} is j's number of events in i-th last time period and x_i is
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* total number of events in i-th last time period.
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*
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* Note that p_{j}'s are normalised, i.e.
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*
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* \Sum_{j} p_{j} = 1,
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*
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* This formula can be straightforwardly computed by maintaing denominator
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* (let's call it 'd') and for each event type its numerator (let's call it
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* 'n_j'). When an event of type 'j' happens, we simply need to do:
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* n_j++; d++;
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*
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* When a new period is declared, we could do:
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* d /= 2
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* for each j
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* n_j /= 2
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*
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* To avoid iteration over all event types, we instead shift numerator of event
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* j lazily when someone asks for a proportion of event j or when event j
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* occurs. This can bit trivially implemented by remembering last period in
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* which something happened with proportion of type j.
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*/
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#include <linux/flex_proportions.h>
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int fprop_global_init(struct fprop_global *p)
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{
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int err;
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p->period = 0;
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/* Use 1 to avoid dealing with periods with 0 events... */
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err = percpu_counter_init(&p->events, 1);
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if (err)
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return err;
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seqcount_init(&p->sequence);
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return 0;
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}
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void fprop_global_destroy(struct fprop_global *p)
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{
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percpu_counter_destroy(&p->events);
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}
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/*
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* Declare @periods new periods. It is upto the caller to make sure period
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* transitions cannot happen in parallel.
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*
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* The function returns true if the proportions are still defined and false
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* if aging zeroed out all events. This can be used to detect whether declaring
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* further periods has any effect.
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*/
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bool fprop_new_period(struct fprop_global *p, int periods)
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{
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u64 events;
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unsigned long flags;
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local_irq_save(flags);
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events = percpu_counter_sum(&p->events);
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/*
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* Don't do anything if there are no events.
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*/
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if (events <= 1) {
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local_irq_restore(flags);
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return false;
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}
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write_seqcount_begin(&p->sequence);
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if (periods < 64)
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events -= events >> periods;
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/* Use addition to avoid losing events happening between sum and set */
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percpu_counter_add(&p->events, -events);
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p->period += periods;
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write_seqcount_end(&p->sequence);
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local_irq_restore(flags);
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return true;
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}
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/*
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* ---- SINGLE ----
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*/
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int fprop_local_init_single(struct fprop_local_single *pl)
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{
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pl->events = 0;
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pl->period = 0;
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raw_spin_lock_init(&pl->lock);
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return 0;
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}
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void fprop_local_destroy_single(struct fprop_local_single *pl)
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{
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}
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static void fprop_reflect_period_single(struct fprop_global *p,
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struct fprop_local_single *pl)
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{
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unsigned int period = p->period;
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unsigned long flags;
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/* Fast path - period didn't change */
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if (pl->period == period)
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return;
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raw_spin_lock_irqsave(&pl->lock, flags);
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/* Someone updated pl->period while we were spinning? */
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if (pl->period >= period) {
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raw_spin_unlock_irqrestore(&pl->lock, flags);
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return;
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}
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/* Aging zeroed our fraction? */
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if (period - pl->period < BITS_PER_LONG)
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pl->events >>= period - pl->period;
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else
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pl->events = 0;
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pl->period = period;
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raw_spin_unlock_irqrestore(&pl->lock, flags);
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}
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/* Event of type pl happened */
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void __fprop_inc_single(struct fprop_global *p, struct fprop_local_single *pl)
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{
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fprop_reflect_period_single(p, pl);
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pl->events++;
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percpu_counter_add(&p->events, 1);
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}
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/* Return fraction of events of type pl */
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void fprop_fraction_single(struct fprop_global *p,
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struct fprop_local_single *pl,
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unsigned long *numerator, unsigned long *denominator)
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{
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unsigned int seq;
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s64 num, den;
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do {
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seq = read_seqcount_begin(&p->sequence);
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fprop_reflect_period_single(p, pl);
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num = pl->events;
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den = percpu_counter_read_positive(&p->events);
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} while (read_seqcount_retry(&p->sequence, seq));
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/*
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* Make fraction <= 1 and denominator > 0 even in presence of percpu
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* counter errors
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*/
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if (den <= num) {
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if (num)
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den = num;
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else
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den = 1;
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}
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*denominator = den;
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*numerator = num;
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}
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/*
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* ---- PERCPU ----
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*/
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#define PROP_BATCH (8*(1+ilog2(nr_cpu_ids)))
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int fprop_local_init_percpu(struct fprop_local_percpu *pl)
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{
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int err;
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err = percpu_counter_init(&pl->events, 0);
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if (err)
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return err;
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pl->period = 0;
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raw_spin_lock_init(&pl->lock);
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return 0;
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}
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void fprop_local_destroy_percpu(struct fprop_local_percpu *pl)
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{
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percpu_counter_destroy(&pl->events);
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}
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static void fprop_reflect_period_percpu(struct fprop_global *p,
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struct fprop_local_percpu *pl)
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{
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unsigned int period = p->period;
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unsigned long flags;
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|
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/* Fast path - period didn't change */
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if (pl->period == period)
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return;
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raw_spin_lock_irqsave(&pl->lock, flags);
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/* Someone updated pl->period while we were spinning? */
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if (pl->period >= period) {
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raw_spin_unlock_irqrestore(&pl->lock, flags);
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return;
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}
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/* Aging zeroed our fraction? */
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if (period - pl->period < BITS_PER_LONG) {
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s64 val = percpu_counter_read(&pl->events);
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if (val < (nr_cpu_ids * PROP_BATCH))
|
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val = percpu_counter_sum(&pl->events);
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|
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__percpu_counter_add(&pl->events,
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-val + (val >> (period-pl->period)), PROP_BATCH);
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} else
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percpu_counter_set(&pl->events, 0);
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pl->period = period;
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raw_spin_unlock_irqrestore(&pl->lock, flags);
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}
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/* Event of type pl happened */
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void __fprop_inc_percpu(struct fprop_global *p, struct fprop_local_percpu *pl)
|
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{
|
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fprop_reflect_period_percpu(p, pl);
|
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__percpu_counter_add(&pl->events, 1, PROP_BATCH);
|
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percpu_counter_add(&p->events, 1);
|
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}
|
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|
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void fprop_fraction_percpu(struct fprop_global *p,
|
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struct fprop_local_percpu *pl,
|
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unsigned long *numerator, unsigned long *denominator)
|
||||
{
|
||||
unsigned int seq;
|
||||
s64 num, den;
|
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|
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do {
|
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seq = read_seqcount_begin(&p->sequence);
|
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fprop_reflect_period_percpu(p, pl);
|
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num = percpu_counter_read_positive(&pl->events);
|
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den = percpu_counter_read_positive(&p->events);
|
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} while (read_seqcount_retry(&p->sequence, seq));
|
||||
|
||||
/*
|
||||
* Make fraction <= 1 and denominator > 0 even in presence of percpu
|
||||
* counter errors
|
||||
*/
|
||||
if (den <= num) {
|
||||
if (num)
|
||||
den = num;
|
||||
else
|
||||
den = 1;
|
||||
}
|
||||
*denominator = den;
|
||||
*numerator = num;
|
||||
}
|
||||
|
||||
/*
|
||||
* Like __fprop_inc_percpu() except that event is counted only if the given
|
||||
* type has fraction smaller than @max_frac/FPROP_FRAC_BASE
|
||||
*/
|
||||
void __fprop_inc_percpu_max(struct fprop_global *p,
|
||||
struct fprop_local_percpu *pl, int max_frac)
|
||||
{
|
||||
if (unlikely(max_frac < FPROP_FRAC_BASE)) {
|
||||
unsigned long numerator, denominator;
|
||||
|
||||
fprop_fraction_percpu(p, pl, &numerator, &denominator);
|
||||
if (numerator >
|
||||
(((u64)denominator) * max_frac) >> FPROP_FRAC_SHIFT)
|
||||
return;
|
||||
} else
|
||||
fprop_reflect_period_percpu(p, pl);
|
||||
__percpu_counter_add(&pl->events, 1, PROP_BATCH);
|
||||
percpu_counter_add(&p->events, 1);
|
||||
}
|
||||
|
|
@ -677,7 +677,7 @@ int bdi_init(struct backing_dev_info *bdi)
|
|||
|
||||
bdi->min_ratio = 0;
|
||||
bdi->max_ratio = 100;
|
||||
bdi->max_prop_frac = PROP_FRAC_BASE;
|
||||
bdi->max_prop_frac = FPROP_FRAC_BASE;
|
||||
spin_lock_init(&bdi->wb_lock);
|
||||
INIT_LIST_HEAD(&bdi->bdi_list);
|
||||
INIT_LIST_HEAD(&bdi->work_list);
|
||||
|
|
@ -700,7 +700,7 @@ int bdi_init(struct backing_dev_info *bdi)
|
|||
bdi->write_bandwidth = INIT_BW;
|
||||
bdi->avg_write_bandwidth = INIT_BW;
|
||||
|
||||
err = prop_local_init_percpu(&bdi->completions);
|
||||
err = fprop_local_init_percpu(&bdi->completions);
|
||||
|
||||
if (err) {
|
||||
err:
|
||||
|
|
@ -744,7 +744,7 @@ void bdi_destroy(struct backing_dev_info *bdi)
|
|||
for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
|
||||
percpu_counter_destroy(&bdi->bdi_stat[i]);
|
||||
|
||||
prop_local_destroy_percpu(&bdi->completions);
|
||||
fprop_local_destroy_percpu(&bdi->completions);
|
||||
}
|
||||
EXPORT_SYMBOL(bdi_destroy);
|
||||
|
||||
|
|
|
|||
|
|
@ -34,6 +34,7 @@
|
|||
#include <linux/syscalls.h>
|
||||
#include <linux/buffer_head.h> /* __set_page_dirty_buffers */
|
||||
#include <linux/pagevec.h>
|
||||
#include <linux/timer.h>
|
||||
#include <trace/events/writeback.h>
|
||||
|
||||
/*
|
||||
|
|
@ -135,7 +136,20 @@ unsigned long global_dirty_limit;
|
|||
* measured in page writeback completions.
|
||||
*
|
||||
*/
|
||||
static struct prop_descriptor vm_completions;
|
||||
static struct fprop_global writeout_completions;
|
||||
|
||||
static void writeout_period(unsigned long t);
|
||||
/* Timer for aging of writeout_completions */
|
||||
static struct timer_list writeout_period_timer =
|
||||
TIMER_DEFERRED_INITIALIZER(writeout_period, 0, 0);
|
||||
static unsigned long writeout_period_time = 0;
|
||||
|
||||
/*
|
||||
* Length of period for aging writeout fractions of bdis. This is an
|
||||
* arbitrarily chosen number. The longer the period, the slower fractions will
|
||||
* reflect changes in current writeout rate.
|
||||
*/
|
||||
#define VM_COMPLETIONS_PERIOD_LEN (3*HZ)
|
||||
|
||||
/*
|
||||
* Work out the current dirty-memory clamping and background writeout
|
||||
|
|
@ -322,34 +336,6 @@ bool zone_dirty_ok(struct zone *zone)
|
|||
zone_page_state(zone, NR_WRITEBACK) <= limit;
|
||||
}
|
||||
|
||||
/*
|
||||
* couple the period to the dirty_ratio:
|
||||
*
|
||||
* period/2 ~ roundup_pow_of_two(dirty limit)
|
||||
*/
|
||||
static int calc_period_shift(void)
|
||||
{
|
||||
unsigned long dirty_total;
|
||||
|
||||
if (vm_dirty_bytes)
|
||||
dirty_total = vm_dirty_bytes / PAGE_SIZE;
|
||||
else
|
||||
dirty_total = (vm_dirty_ratio * global_dirtyable_memory()) /
|
||||
100;
|
||||
return 2 + ilog2(dirty_total - 1);
|
||||
}
|
||||
|
||||
/*
|
||||
* update the period when the dirty threshold changes.
|
||||
*/
|
||||
static void update_completion_period(void)
|
||||
{
|
||||
int shift = calc_period_shift();
|
||||
prop_change_shift(&vm_completions, shift);
|
||||
|
||||
writeback_set_ratelimit();
|
||||
}
|
||||
|
||||
int dirty_background_ratio_handler(struct ctl_table *table, int write,
|
||||
void __user *buffer, size_t *lenp,
|
||||
loff_t *ppos)
|
||||
|
|
@ -383,7 +369,7 @@ int dirty_ratio_handler(struct ctl_table *table, int write,
|
|||
|
||||
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
||||
if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
|
||||
update_completion_period();
|
||||
writeback_set_ratelimit();
|
||||
vm_dirty_bytes = 0;
|
||||
}
|
||||
return ret;
|
||||
|
|
@ -398,12 +384,21 @@ int dirty_bytes_handler(struct ctl_table *table, int write,
|
|||
|
||||
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
|
||||
if (ret == 0 && write && vm_dirty_bytes != old_bytes) {
|
||||
update_completion_period();
|
||||
writeback_set_ratelimit();
|
||||
vm_dirty_ratio = 0;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
||||
static unsigned long wp_next_time(unsigned long cur_time)
|
||||
{
|
||||
cur_time += VM_COMPLETIONS_PERIOD_LEN;
|
||||
/* 0 has a special meaning... */
|
||||
if (!cur_time)
|
||||
return 1;
|
||||
return cur_time;
|
||||
}
|
||||
|
||||
/*
|
||||
* Increment the BDI's writeout completion count and the global writeout
|
||||
* completion count. Called from test_clear_page_writeback().
|
||||
|
|
@ -411,8 +406,19 @@ int dirty_bytes_handler(struct ctl_table *table, int write,
|
|||
static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
|
||||
{
|
||||
__inc_bdi_stat(bdi, BDI_WRITTEN);
|
||||
__prop_inc_percpu_max(&vm_completions, &bdi->completions,
|
||||
bdi->max_prop_frac);
|
||||
__fprop_inc_percpu_max(&writeout_completions, &bdi->completions,
|
||||
bdi->max_prop_frac);
|
||||
/* First event after period switching was turned off? */
|
||||
if (!unlikely(writeout_period_time)) {
|
||||
/*
|
||||
* We can race with other __bdi_writeout_inc calls here but
|
||||
* it does not cause any harm since the resulting time when
|
||||
* timer will fire and what is in writeout_period_time will be
|
||||
* roughly the same.
|
||||
*/
|
||||
writeout_period_time = wp_next_time(jiffies);
|
||||
mod_timer(&writeout_period_timer, writeout_period_time);
|
||||
}
|
||||
}
|
||||
|
||||
void bdi_writeout_inc(struct backing_dev_info *bdi)
|
||||
|
|
@ -431,10 +437,32 @@ EXPORT_SYMBOL_GPL(bdi_writeout_inc);
|
|||
static void bdi_writeout_fraction(struct backing_dev_info *bdi,
|
||||
long *numerator, long *denominator)
|
||||
{
|
||||
prop_fraction_percpu(&vm_completions, &bdi->completions,
|
||||
fprop_fraction_percpu(&writeout_completions, &bdi->completions,
|
||||
numerator, denominator);
|
||||
}
|
||||
|
||||
/*
|
||||
* On idle system, we can be called long after we scheduled because we use
|
||||
* deferred timers so count with missed periods.
|
||||
*/
|
||||
static void writeout_period(unsigned long t)
|
||||
{
|
||||
int miss_periods = (jiffies - writeout_period_time) /
|
||||
VM_COMPLETIONS_PERIOD_LEN;
|
||||
|
||||
if (fprop_new_period(&writeout_completions, miss_periods + 1)) {
|
||||
writeout_period_time = wp_next_time(writeout_period_time +
|
||||
miss_periods * VM_COMPLETIONS_PERIOD_LEN);
|
||||
mod_timer(&writeout_period_timer, writeout_period_time);
|
||||
} else {
|
||||
/*
|
||||
* Aging has zeroed all fractions. Stop wasting CPU on period
|
||||
* updates.
|
||||
*/
|
||||
writeout_period_time = 0;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* bdi_min_ratio keeps the sum of the minimum dirty shares of all
|
||||
* registered backing devices, which, for obvious reasons, can not
|
||||
|
|
@ -475,7 +503,7 @@ int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
|
|||
ret = -EINVAL;
|
||||
} else {
|
||||
bdi->max_ratio = max_ratio;
|
||||
bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100;
|
||||
bdi->max_prop_frac = (FPROP_FRAC_BASE * max_ratio) / 100;
|
||||
}
|
||||
spin_unlock_bh(&bdi_lock);
|
||||
|
||||
|
|
@ -918,7 +946,7 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
|
|||
* bdi->dirty_ratelimit = balanced_dirty_ratelimit;
|
||||
*
|
||||
* However to get a more stable dirty_ratelimit, the below elaborated
|
||||
* code makes use of task_ratelimit to filter out sigular points and
|
||||
* code makes use of task_ratelimit to filter out singular points and
|
||||
* limit the step size.
|
||||
*
|
||||
* The below code essentially only uses the relative value of
|
||||
|
|
@ -941,7 +969,7 @@ static void bdi_update_dirty_ratelimit(struct backing_dev_info *bdi,
|
|||
* feel and care are stable dirty rate and small position error.
|
||||
*
|
||||
* |task_ratelimit - dirty_ratelimit| is used to limit the step size
|
||||
* and filter out the sigular points of balanced_dirty_ratelimit. Which
|
||||
* and filter out the singular points of balanced_dirty_ratelimit. Which
|
||||
* keeps jumping around randomly and can even leap far away at times
|
||||
* due to the small 200ms estimation period of dirty_rate (we want to
|
||||
* keep that period small to reduce time lags).
|
||||
|
|
@ -1606,13 +1634,10 @@ static struct notifier_block __cpuinitdata ratelimit_nb = {
|
|||
*/
|
||||
void __init page_writeback_init(void)
|
||||
{
|
||||
int shift;
|
||||
|
||||
writeback_set_ratelimit();
|
||||
register_cpu_notifier(&ratelimit_nb);
|
||||
|
||||
shift = calc_period_shift();
|
||||
prop_descriptor_init(&vm_completions, shift);
|
||||
fprop_global_init(&writeout_completions);
|
||||
}
|
||||
|
||||
/**
|
||||
|
|
|
|||
Loading…
Reference in New Issue