![Ingo Molnar](/assets/img/avatar_default.png)
We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which will have to be picked up from other headers and .c files. Create a trivial placeholder <linux/sched/clock.h> file that just maps to <linux/sched.h> to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
531 lines
12 KiB
C
531 lines
12 KiB
C
/*
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* background writeback - scan btree for dirty data and write it to the backing
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* device
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*
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* Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
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* Copyright 2012 Google, Inc.
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*/
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#include "bcache.h"
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#include "btree.h"
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#include "debug.h"
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#include "writeback.h"
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#include <linux/delay.h>
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#include <linux/kthread.h>
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#include <linux/sched/clock.h>
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#include <trace/events/bcache.h>
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/* Rate limiting */
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static void __update_writeback_rate(struct cached_dev *dc)
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{
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struct cache_set *c = dc->disk.c;
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uint64_t cache_sectors = c->nbuckets * c->sb.bucket_size;
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uint64_t cache_dirty_target =
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div_u64(cache_sectors * dc->writeback_percent, 100);
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int64_t target = div64_u64(cache_dirty_target * bdev_sectors(dc->bdev),
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c->cached_dev_sectors);
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/* PD controller */
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int64_t dirty = bcache_dev_sectors_dirty(&dc->disk);
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int64_t derivative = dirty - dc->disk.sectors_dirty_last;
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int64_t proportional = dirty - target;
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int64_t change;
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dc->disk.sectors_dirty_last = dirty;
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/* Scale to sectors per second */
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proportional *= dc->writeback_rate_update_seconds;
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proportional = div_s64(proportional, dc->writeback_rate_p_term_inverse);
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derivative = div_s64(derivative, dc->writeback_rate_update_seconds);
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derivative = ewma_add(dc->disk.sectors_dirty_derivative, derivative,
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(dc->writeback_rate_d_term /
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dc->writeback_rate_update_seconds) ?: 1, 0);
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derivative *= dc->writeback_rate_d_term;
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derivative = div_s64(derivative, dc->writeback_rate_p_term_inverse);
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change = proportional + derivative;
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/* Don't increase writeback rate if the device isn't keeping up */
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if (change > 0 &&
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time_after64(local_clock(),
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dc->writeback_rate.next + NSEC_PER_MSEC))
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change = 0;
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dc->writeback_rate.rate =
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clamp_t(int64_t, (int64_t) dc->writeback_rate.rate + change,
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1, NSEC_PER_MSEC);
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dc->writeback_rate_proportional = proportional;
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dc->writeback_rate_derivative = derivative;
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dc->writeback_rate_change = change;
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dc->writeback_rate_target = target;
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}
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static void update_writeback_rate(struct work_struct *work)
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{
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struct cached_dev *dc = container_of(to_delayed_work(work),
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struct cached_dev,
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writeback_rate_update);
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down_read(&dc->writeback_lock);
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if (atomic_read(&dc->has_dirty) &&
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dc->writeback_percent)
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__update_writeback_rate(dc);
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up_read(&dc->writeback_lock);
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schedule_delayed_work(&dc->writeback_rate_update,
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dc->writeback_rate_update_seconds * HZ);
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}
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static unsigned writeback_delay(struct cached_dev *dc, unsigned sectors)
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{
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if (test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) ||
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!dc->writeback_percent)
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return 0;
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return bch_next_delay(&dc->writeback_rate, sectors);
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}
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struct dirty_io {
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struct closure cl;
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struct cached_dev *dc;
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struct bio bio;
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};
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static void dirty_init(struct keybuf_key *w)
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{
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struct dirty_io *io = w->private;
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struct bio *bio = &io->bio;
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bio_init(bio, bio->bi_inline_vecs,
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DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS));
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if (!io->dc->writeback_percent)
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bio_set_prio(bio, IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0));
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bio->bi_iter.bi_size = KEY_SIZE(&w->key) << 9;
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bio->bi_private = w;
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bch_bio_map(bio, NULL);
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}
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static void dirty_io_destructor(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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kfree(io);
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}
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static void write_dirty_finish(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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struct keybuf_key *w = io->bio.bi_private;
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struct cached_dev *dc = io->dc;
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bio_free_pages(&io->bio);
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/* This is kind of a dumb way of signalling errors. */
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if (KEY_DIRTY(&w->key)) {
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int ret;
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unsigned i;
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struct keylist keys;
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bch_keylist_init(&keys);
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bkey_copy(keys.top, &w->key);
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SET_KEY_DIRTY(keys.top, false);
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bch_keylist_push(&keys);
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for (i = 0; i < KEY_PTRS(&w->key); i++)
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atomic_inc(&PTR_BUCKET(dc->disk.c, &w->key, i)->pin);
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ret = bch_btree_insert(dc->disk.c, &keys, NULL, &w->key);
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if (ret)
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trace_bcache_writeback_collision(&w->key);
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atomic_long_inc(ret
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? &dc->disk.c->writeback_keys_failed
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: &dc->disk.c->writeback_keys_done);
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}
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bch_keybuf_del(&dc->writeback_keys, w);
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up(&dc->in_flight);
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closure_return_with_destructor(cl, dirty_io_destructor);
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}
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static void dirty_endio(struct bio *bio)
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{
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struct keybuf_key *w = bio->bi_private;
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struct dirty_io *io = w->private;
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if (bio->bi_error)
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SET_KEY_DIRTY(&w->key, false);
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closure_put(&io->cl);
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}
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static void write_dirty(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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struct keybuf_key *w = io->bio.bi_private;
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dirty_init(w);
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bio_set_op_attrs(&io->bio, REQ_OP_WRITE, 0);
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io->bio.bi_iter.bi_sector = KEY_START(&w->key);
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io->bio.bi_bdev = io->dc->bdev;
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io->bio.bi_end_io = dirty_endio;
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closure_bio_submit(&io->bio, cl);
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continue_at(cl, write_dirty_finish, system_wq);
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}
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static void read_dirty_endio(struct bio *bio)
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{
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struct keybuf_key *w = bio->bi_private;
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struct dirty_io *io = w->private;
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bch_count_io_errors(PTR_CACHE(io->dc->disk.c, &w->key, 0),
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bio->bi_error, "reading dirty data from cache");
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dirty_endio(bio);
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}
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static void read_dirty_submit(struct closure *cl)
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{
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struct dirty_io *io = container_of(cl, struct dirty_io, cl);
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closure_bio_submit(&io->bio, cl);
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continue_at(cl, write_dirty, system_wq);
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}
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static void read_dirty(struct cached_dev *dc)
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{
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unsigned delay = 0;
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struct keybuf_key *w;
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struct dirty_io *io;
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struct closure cl;
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closure_init_stack(&cl);
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/*
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* XXX: if we error, background writeback just spins. Should use some
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* mempools.
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*/
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while (!kthread_should_stop()) {
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w = bch_keybuf_next(&dc->writeback_keys);
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if (!w)
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break;
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BUG_ON(ptr_stale(dc->disk.c, &w->key, 0));
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if (KEY_START(&w->key) != dc->last_read ||
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jiffies_to_msecs(delay) > 50)
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while (!kthread_should_stop() && delay)
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delay = schedule_timeout_interruptible(delay);
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dc->last_read = KEY_OFFSET(&w->key);
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io = kzalloc(sizeof(struct dirty_io) + sizeof(struct bio_vec)
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* DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
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GFP_KERNEL);
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if (!io)
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goto err;
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w->private = io;
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io->dc = dc;
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dirty_init(w);
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bio_set_op_attrs(&io->bio, REQ_OP_READ, 0);
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io->bio.bi_iter.bi_sector = PTR_OFFSET(&w->key, 0);
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io->bio.bi_bdev = PTR_CACHE(dc->disk.c,
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&w->key, 0)->bdev;
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io->bio.bi_end_io = read_dirty_endio;
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if (bio_alloc_pages(&io->bio, GFP_KERNEL))
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goto err_free;
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trace_bcache_writeback(&w->key);
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down(&dc->in_flight);
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closure_call(&io->cl, read_dirty_submit, NULL, &cl);
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delay = writeback_delay(dc, KEY_SIZE(&w->key));
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}
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if (0) {
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err_free:
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kfree(w->private);
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err:
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bch_keybuf_del(&dc->writeback_keys, w);
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}
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/*
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* Wait for outstanding writeback IOs to finish (and keybuf slots to be
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* freed) before refilling again
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*/
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closure_sync(&cl);
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}
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/* Scan for dirty data */
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void bcache_dev_sectors_dirty_add(struct cache_set *c, unsigned inode,
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uint64_t offset, int nr_sectors)
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{
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struct bcache_device *d = c->devices[inode];
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unsigned stripe_offset, stripe, sectors_dirty;
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if (!d)
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return;
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stripe = offset_to_stripe(d, offset);
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stripe_offset = offset & (d->stripe_size - 1);
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while (nr_sectors) {
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int s = min_t(unsigned, abs(nr_sectors),
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d->stripe_size - stripe_offset);
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if (nr_sectors < 0)
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s = -s;
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if (stripe >= d->nr_stripes)
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return;
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sectors_dirty = atomic_add_return(s,
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d->stripe_sectors_dirty + stripe);
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if (sectors_dirty == d->stripe_size)
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set_bit(stripe, d->full_dirty_stripes);
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else
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clear_bit(stripe, d->full_dirty_stripes);
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nr_sectors -= s;
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stripe_offset = 0;
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stripe++;
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}
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}
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static bool dirty_pred(struct keybuf *buf, struct bkey *k)
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{
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struct cached_dev *dc = container_of(buf, struct cached_dev, writeback_keys);
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BUG_ON(KEY_INODE(k) != dc->disk.id);
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return KEY_DIRTY(k);
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}
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static void refill_full_stripes(struct cached_dev *dc)
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{
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struct keybuf *buf = &dc->writeback_keys;
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unsigned start_stripe, stripe, next_stripe;
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bool wrapped = false;
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stripe = offset_to_stripe(&dc->disk, KEY_OFFSET(&buf->last_scanned));
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if (stripe >= dc->disk.nr_stripes)
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stripe = 0;
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start_stripe = stripe;
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while (1) {
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stripe = find_next_bit(dc->disk.full_dirty_stripes,
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dc->disk.nr_stripes, stripe);
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if (stripe == dc->disk.nr_stripes)
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goto next;
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next_stripe = find_next_zero_bit(dc->disk.full_dirty_stripes,
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dc->disk.nr_stripes, stripe);
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buf->last_scanned = KEY(dc->disk.id,
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stripe * dc->disk.stripe_size, 0);
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bch_refill_keybuf(dc->disk.c, buf,
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&KEY(dc->disk.id,
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next_stripe * dc->disk.stripe_size, 0),
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dirty_pred);
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if (array_freelist_empty(&buf->freelist))
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return;
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stripe = next_stripe;
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next:
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if (wrapped && stripe > start_stripe)
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return;
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if (stripe == dc->disk.nr_stripes) {
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stripe = 0;
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wrapped = true;
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}
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}
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}
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/*
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* Returns true if we scanned the entire disk
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*/
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static bool refill_dirty(struct cached_dev *dc)
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{
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struct keybuf *buf = &dc->writeback_keys;
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struct bkey start = KEY(dc->disk.id, 0, 0);
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struct bkey end = KEY(dc->disk.id, MAX_KEY_OFFSET, 0);
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struct bkey start_pos;
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/*
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* make sure keybuf pos is inside the range for this disk - at bringup
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* we might not be attached yet so this disk's inode nr isn't
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* initialized then
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*/
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if (bkey_cmp(&buf->last_scanned, &start) < 0 ||
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bkey_cmp(&buf->last_scanned, &end) > 0)
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buf->last_scanned = start;
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if (dc->partial_stripes_expensive) {
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refill_full_stripes(dc);
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if (array_freelist_empty(&buf->freelist))
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return false;
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}
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start_pos = buf->last_scanned;
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bch_refill_keybuf(dc->disk.c, buf, &end, dirty_pred);
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if (bkey_cmp(&buf->last_scanned, &end) < 0)
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return false;
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/*
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* If we get to the end start scanning again from the beginning, and
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* only scan up to where we initially started scanning from:
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*/
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buf->last_scanned = start;
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bch_refill_keybuf(dc->disk.c, buf, &start_pos, dirty_pred);
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return bkey_cmp(&buf->last_scanned, &start_pos) >= 0;
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}
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static int bch_writeback_thread(void *arg)
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{
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struct cached_dev *dc = arg;
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bool searched_full_index;
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while (!kthread_should_stop()) {
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down_write(&dc->writeback_lock);
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if (!atomic_read(&dc->has_dirty) ||
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(!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags) &&
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!dc->writeback_running)) {
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up_write(&dc->writeback_lock);
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set_current_state(TASK_INTERRUPTIBLE);
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if (kthread_should_stop())
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return 0;
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schedule();
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continue;
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}
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searched_full_index = refill_dirty(dc);
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if (searched_full_index &&
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RB_EMPTY_ROOT(&dc->writeback_keys.keys)) {
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atomic_set(&dc->has_dirty, 0);
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cached_dev_put(dc);
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SET_BDEV_STATE(&dc->sb, BDEV_STATE_CLEAN);
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bch_write_bdev_super(dc, NULL);
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}
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up_write(&dc->writeback_lock);
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bch_ratelimit_reset(&dc->writeback_rate);
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read_dirty(dc);
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if (searched_full_index) {
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unsigned delay = dc->writeback_delay * HZ;
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while (delay &&
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!kthread_should_stop() &&
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!test_bit(BCACHE_DEV_DETACHING, &dc->disk.flags))
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delay = schedule_timeout_interruptible(delay);
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}
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}
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return 0;
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}
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/* Init */
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struct sectors_dirty_init {
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struct btree_op op;
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unsigned inode;
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};
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static int sectors_dirty_init_fn(struct btree_op *_op, struct btree *b,
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struct bkey *k)
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{
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struct sectors_dirty_init *op = container_of(_op,
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struct sectors_dirty_init, op);
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if (KEY_INODE(k) > op->inode)
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return MAP_DONE;
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if (KEY_DIRTY(k))
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bcache_dev_sectors_dirty_add(b->c, KEY_INODE(k),
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KEY_START(k), KEY_SIZE(k));
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return MAP_CONTINUE;
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}
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void bch_sectors_dirty_init(struct cached_dev *dc)
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{
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struct sectors_dirty_init op;
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bch_btree_op_init(&op.op, -1);
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op.inode = dc->disk.id;
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bch_btree_map_keys(&op.op, dc->disk.c, &KEY(op.inode, 0, 0),
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sectors_dirty_init_fn, 0);
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dc->disk.sectors_dirty_last = bcache_dev_sectors_dirty(&dc->disk);
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}
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void bch_cached_dev_writeback_init(struct cached_dev *dc)
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{
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sema_init(&dc->in_flight, 64);
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init_rwsem(&dc->writeback_lock);
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bch_keybuf_init(&dc->writeback_keys);
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dc->writeback_metadata = true;
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dc->writeback_running = true;
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dc->writeback_percent = 10;
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dc->writeback_delay = 30;
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dc->writeback_rate.rate = 1024;
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dc->writeback_rate_update_seconds = 5;
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dc->writeback_rate_d_term = 30;
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dc->writeback_rate_p_term_inverse = 6000;
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INIT_DELAYED_WORK(&dc->writeback_rate_update, update_writeback_rate);
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}
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int bch_cached_dev_writeback_start(struct cached_dev *dc)
|
|
{
|
|
dc->writeback_thread = kthread_create(bch_writeback_thread, dc,
|
|
"bcache_writeback");
|
|
if (IS_ERR(dc->writeback_thread))
|
|
return PTR_ERR(dc->writeback_thread);
|
|
|
|
schedule_delayed_work(&dc->writeback_rate_update,
|
|
dc->writeback_rate_update_seconds * HZ);
|
|
|
|
bch_writeback_queue(dc);
|
|
|
|
return 0;
|
|
}
|