![Omar Sandoval](/assets/img/avatar_default.png)
Commit 8cf4666020
("kyber: fix hang on domain token wait queue") fixed
a hang caused by leaving wait entries on the domain token wait queue
after the __sbitmap_queue_get() retry succeeded, making that wait entry
a "dud" which won't in turn wake more entries up. However, we can also
get a dud entry if kyber_get_domain_token() fails once but is then
called again and succeeds. This can happen if the hardware queue is
rerun for some other reason, or, more likely, kyber_dispatch_request()
tries the same domain twice.
The fix is to remove our entry from the wait queue whenever we
successfully get a token. The only complication is that we might be on
one of many wait queues in the struct sbitmap_queue, but that's easily
fixed by remembering which wait queue we were put on.
While we're here, only initialize the wait queue entry once instead of
on every wait, and use spin_lock_irq() instead of spin_lock_irqsave(),
since this is always called from process context with irqs enabled.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
866 lines
22 KiB
C
866 lines
22 KiB
C
/*
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* The Kyber I/O scheduler. Controls latency by throttling queue depths using
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* scalable techniques.
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*
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* Copyright (C) 2017 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#include <linux/kernel.h>
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#include <linux/blkdev.h>
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#include <linux/blk-mq.h>
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#include <linux/elevator.h>
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#include <linux/module.h>
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#include <linux/sbitmap.h>
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#include "blk.h"
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#include "blk-mq.h"
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#include "blk-mq-debugfs.h"
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#include "blk-mq-sched.h"
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#include "blk-mq-tag.h"
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#include "blk-stat.h"
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/* Scheduling domains. */
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enum {
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KYBER_READ,
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KYBER_SYNC_WRITE,
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KYBER_OTHER, /* Async writes, discard, etc. */
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KYBER_NUM_DOMAINS,
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};
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enum {
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KYBER_MIN_DEPTH = 256,
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/*
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* In order to prevent starvation of synchronous requests by a flood of
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* asynchronous requests, we reserve 25% of requests for synchronous
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* operations.
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*/
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KYBER_ASYNC_PERCENT = 75,
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};
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/*
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* Initial device-wide depths for each scheduling domain.
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*
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* Even for fast devices with lots of tags like NVMe, you can saturate
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* the device with only a fraction of the maximum possible queue depth.
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* So, we cap these to a reasonable value.
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*/
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static const unsigned int kyber_depth[] = {
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[KYBER_READ] = 256,
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[KYBER_SYNC_WRITE] = 128,
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[KYBER_OTHER] = 64,
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};
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/*
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* Scheduling domain batch sizes. We favor reads.
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*/
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static const unsigned int kyber_batch_size[] = {
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[KYBER_READ] = 16,
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[KYBER_SYNC_WRITE] = 8,
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[KYBER_OTHER] = 8,
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};
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struct kyber_queue_data {
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struct request_queue *q;
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struct blk_stat_callback *cb;
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/*
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* The device is divided into multiple scheduling domains based on the
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* request type. Each domain has a fixed number of in-flight requests of
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* that type device-wide, limited by these tokens.
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*/
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struct sbitmap_queue domain_tokens[KYBER_NUM_DOMAINS];
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/*
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* Async request percentage, converted to per-word depth for
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* sbitmap_get_shallow().
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*/
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unsigned int async_depth;
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/* Target latencies in nanoseconds. */
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u64 read_lat_nsec, write_lat_nsec;
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};
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struct kyber_hctx_data {
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spinlock_t lock;
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struct list_head rqs[KYBER_NUM_DOMAINS];
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unsigned int cur_domain;
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unsigned int batching;
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wait_queue_entry_t domain_wait[KYBER_NUM_DOMAINS];
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struct sbq_wait_state *domain_ws[KYBER_NUM_DOMAINS];
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atomic_t wait_index[KYBER_NUM_DOMAINS];
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};
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static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
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void *key);
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static int rq_sched_domain(const struct request *rq)
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{
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unsigned int op = rq->cmd_flags;
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if ((op & REQ_OP_MASK) == REQ_OP_READ)
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return KYBER_READ;
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else if ((op & REQ_OP_MASK) == REQ_OP_WRITE && op_is_sync(op))
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return KYBER_SYNC_WRITE;
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else
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return KYBER_OTHER;
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}
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enum {
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NONE = 0,
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GOOD = 1,
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GREAT = 2,
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BAD = -1,
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AWFUL = -2,
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};
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#define IS_GOOD(status) ((status) > 0)
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#define IS_BAD(status) ((status) < 0)
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static int kyber_lat_status(struct blk_stat_callback *cb,
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unsigned int sched_domain, u64 target)
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{
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u64 latency;
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if (!cb->stat[sched_domain].nr_samples)
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return NONE;
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latency = cb->stat[sched_domain].mean;
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if (latency >= 2 * target)
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return AWFUL;
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else if (latency > target)
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return BAD;
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else if (latency <= target / 2)
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return GREAT;
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else /* (latency <= target) */
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return GOOD;
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}
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/*
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* Adjust the read or synchronous write depth given the status of reads and
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* writes. The goal is that the latencies of the two domains are fair (i.e., if
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* one is good, then the other is good).
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*/
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static void kyber_adjust_rw_depth(struct kyber_queue_data *kqd,
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unsigned int sched_domain, int this_status,
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int other_status)
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{
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unsigned int orig_depth, depth;
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/*
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* If this domain had no samples, or reads and writes are both good or
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* both bad, don't adjust the depth.
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*/
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if (this_status == NONE ||
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(IS_GOOD(this_status) && IS_GOOD(other_status)) ||
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(IS_BAD(this_status) && IS_BAD(other_status)))
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return;
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orig_depth = depth = kqd->domain_tokens[sched_domain].sb.depth;
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if (other_status == NONE) {
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depth++;
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} else {
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switch (this_status) {
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case GOOD:
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if (other_status == AWFUL)
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depth -= max(depth / 4, 1U);
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else
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depth -= max(depth / 8, 1U);
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break;
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case GREAT:
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if (other_status == AWFUL)
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depth /= 2;
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else
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depth -= max(depth / 4, 1U);
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break;
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case BAD:
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depth++;
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break;
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case AWFUL:
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if (other_status == GREAT)
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depth += 2;
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else
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depth++;
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break;
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}
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}
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depth = clamp(depth, 1U, kyber_depth[sched_domain]);
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if (depth != orig_depth)
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sbitmap_queue_resize(&kqd->domain_tokens[sched_domain], depth);
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}
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/*
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* Adjust the depth of other requests given the status of reads and synchronous
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* writes. As long as either domain is doing fine, we don't throttle, but if
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* both domains are doing badly, we throttle heavily.
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*/
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static void kyber_adjust_other_depth(struct kyber_queue_data *kqd,
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int read_status, int write_status,
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bool have_samples)
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{
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unsigned int orig_depth, depth;
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int status;
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orig_depth = depth = kqd->domain_tokens[KYBER_OTHER].sb.depth;
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if (read_status == NONE && write_status == NONE) {
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depth += 2;
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} else if (have_samples) {
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if (read_status == NONE)
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status = write_status;
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else if (write_status == NONE)
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status = read_status;
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else
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status = max(read_status, write_status);
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switch (status) {
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case GREAT:
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depth += 2;
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break;
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case GOOD:
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depth++;
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break;
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case BAD:
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depth -= max(depth / 4, 1U);
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break;
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case AWFUL:
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depth /= 2;
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break;
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}
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}
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depth = clamp(depth, 1U, kyber_depth[KYBER_OTHER]);
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if (depth != orig_depth)
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sbitmap_queue_resize(&kqd->domain_tokens[KYBER_OTHER], depth);
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}
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/*
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* Apply heuristics for limiting queue depths based on gathered latency
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* statistics.
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*/
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static void kyber_stat_timer_fn(struct blk_stat_callback *cb)
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{
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struct kyber_queue_data *kqd = cb->data;
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int read_status, write_status;
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read_status = kyber_lat_status(cb, KYBER_READ, kqd->read_lat_nsec);
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write_status = kyber_lat_status(cb, KYBER_SYNC_WRITE, kqd->write_lat_nsec);
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kyber_adjust_rw_depth(kqd, KYBER_READ, read_status, write_status);
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kyber_adjust_rw_depth(kqd, KYBER_SYNC_WRITE, write_status, read_status);
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kyber_adjust_other_depth(kqd, read_status, write_status,
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cb->stat[KYBER_OTHER].nr_samples != 0);
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/*
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* Continue monitoring latencies if we aren't hitting the targets or
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* we're still throttling other requests.
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*/
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if (!blk_stat_is_active(kqd->cb) &&
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((IS_BAD(read_status) || IS_BAD(write_status) ||
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kqd->domain_tokens[KYBER_OTHER].sb.depth < kyber_depth[KYBER_OTHER])))
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blk_stat_activate_msecs(kqd->cb, 100);
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}
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static unsigned int kyber_sched_tags_shift(struct kyber_queue_data *kqd)
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{
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/*
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* All of the hardware queues have the same depth, so we can just grab
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* the shift of the first one.
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*/
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return kqd->q->queue_hw_ctx[0]->sched_tags->bitmap_tags.sb.shift;
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}
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static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
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{
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struct kyber_queue_data *kqd;
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unsigned int max_tokens;
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unsigned int shift;
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int ret = -ENOMEM;
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int i;
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kqd = kmalloc_node(sizeof(*kqd), GFP_KERNEL, q->node);
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if (!kqd)
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goto err;
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kqd->q = q;
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kqd->cb = blk_stat_alloc_callback(kyber_stat_timer_fn, rq_sched_domain,
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KYBER_NUM_DOMAINS, kqd);
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if (!kqd->cb)
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goto err_kqd;
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/*
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* The maximum number of tokens for any scheduling domain is at least
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* the queue depth of a single hardware queue. If the hardware doesn't
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* have many tags, still provide a reasonable number.
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*/
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max_tokens = max_t(unsigned int, q->tag_set->queue_depth,
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KYBER_MIN_DEPTH);
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for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
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WARN_ON(!kyber_depth[i]);
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WARN_ON(!kyber_batch_size[i]);
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ret = sbitmap_queue_init_node(&kqd->domain_tokens[i],
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max_tokens, -1, false, GFP_KERNEL,
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q->node);
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if (ret) {
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while (--i >= 0)
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sbitmap_queue_free(&kqd->domain_tokens[i]);
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goto err_cb;
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}
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sbitmap_queue_resize(&kqd->domain_tokens[i], kyber_depth[i]);
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}
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shift = kyber_sched_tags_shift(kqd);
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kqd->async_depth = (1U << shift) * KYBER_ASYNC_PERCENT / 100U;
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kqd->read_lat_nsec = 2000000ULL;
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kqd->write_lat_nsec = 10000000ULL;
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return kqd;
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err_cb:
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blk_stat_free_callback(kqd->cb);
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err_kqd:
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kfree(kqd);
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err:
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return ERR_PTR(ret);
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}
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static int kyber_init_sched(struct request_queue *q, struct elevator_type *e)
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{
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struct kyber_queue_data *kqd;
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struct elevator_queue *eq;
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eq = elevator_alloc(q, e);
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if (!eq)
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return -ENOMEM;
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kqd = kyber_queue_data_alloc(q);
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if (IS_ERR(kqd)) {
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kobject_put(&eq->kobj);
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return PTR_ERR(kqd);
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}
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eq->elevator_data = kqd;
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q->elevator = eq;
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blk_stat_add_callback(q, kqd->cb);
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return 0;
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}
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static void kyber_exit_sched(struct elevator_queue *e)
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{
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struct kyber_queue_data *kqd = e->elevator_data;
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struct request_queue *q = kqd->q;
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int i;
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blk_stat_remove_callback(q, kqd->cb);
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for (i = 0; i < KYBER_NUM_DOMAINS; i++)
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sbitmap_queue_free(&kqd->domain_tokens[i]);
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blk_stat_free_callback(kqd->cb);
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kfree(kqd);
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}
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static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
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{
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struct kyber_hctx_data *khd;
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int i;
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khd = kmalloc_node(sizeof(*khd), GFP_KERNEL, hctx->numa_node);
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if (!khd)
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return -ENOMEM;
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spin_lock_init(&khd->lock);
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for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
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INIT_LIST_HEAD(&khd->rqs[i]);
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init_waitqueue_func_entry(&khd->domain_wait[i],
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kyber_domain_wake);
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khd->domain_wait[i].private = hctx;
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INIT_LIST_HEAD(&khd->domain_wait[i].entry);
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atomic_set(&khd->wait_index[i], 0);
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}
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khd->cur_domain = 0;
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khd->batching = 0;
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hctx->sched_data = khd;
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return 0;
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}
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static void kyber_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
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{
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kfree(hctx->sched_data);
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}
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static int rq_get_domain_token(struct request *rq)
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{
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return (long)rq->elv.priv[0];
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}
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static void rq_set_domain_token(struct request *rq, int token)
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{
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rq->elv.priv[0] = (void *)(long)token;
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}
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static void rq_clear_domain_token(struct kyber_queue_data *kqd,
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struct request *rq)
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{
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unsigned int sched_domain;
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int nr;
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nr = rq_get_domain_token(rq);
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if (nr != -1) {
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sched_domain = rq_sched_domain(rq);
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sbitmap_queue_clear(&kqd->domain_tokens[sched_domain], nr,
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rq->mq_ctx->cpu);
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}
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}
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static void kyber_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
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{
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/*
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* We use the scheduler tags as per-hardware queue queueing tokens.
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* Async requests can be limited at this stage.
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*/
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if (!op_is_sync(op)) {
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struct kyber_queue_data *kqd = data->q->elevator->elevator_data;
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data->shallow_depth = kqd->async_depth;
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}
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}
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static void kyber_prepare_request(struct request *rq, struct bio *bio)
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{
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rq_set_domain_token(rq, -1);
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}
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static void kyber_finish_request(struct request *rq)
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{
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struct kyber_queue_data *kqd = rq->q->elevator->elevator_data;
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rq_clear_domain_token(kqd, rq);
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}
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static void kyber_completed_request(struct request *rq)
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{
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struct request_queue *q = rq->q;
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struct kyber_queue_data *kqd = q->elevator->elevator_data;
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unsigned int sched_domain;
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u64 now, latency, target;
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/*
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* Check if this request met our latency goal. If not, quickly gather
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* some statistics and start throttling.
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*/
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sched_domain = rq_sched_domain(rq);
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switch (sched_domain) {
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case KYBER_READ:
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target = kqd->read_lat_nsec;
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break;
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case KYBER_SYNC_WRITE:
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target = kqd->write_lat_nsec;
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break;
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default:
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return;
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}
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/* If we are already monitoring latencies, don't check again. */
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if (blk_stat_is_active(kqd->cb))
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return;
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now = __blk_stat_time(ktime_to_ns(ktime_get()));
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if (now < blk_stat_time(&rq->issue_stat))
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return;
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latency = now - blk_stat_time(&rq->issue_stat);
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if (latency > target)
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blk_stat_activate_msecs(kqd->cb, 10);
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}
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static void kyber_flush_busy_ctxs(struct kyber_hctx_data *khd,
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struct blk_mq_hw_ctx *hctx)
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{
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LIST_HEAD(rq_list);
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struct request *rq, *next;
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blk_mq_flush_busy_ctxs(hctx, &rq_list);
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list_for_each_entry_safe(rq, next, &rq_list, queuelist) {
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|
unsigned int sched_domain;
|
|
|
|
sched_domain = rq_sched_domain(rq);
|
|
list_move_tail(&rq->queuelist, &khd->rqs[sched_domain]);
|
|
}
|
|
}
|
|
|
|
static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
|
|
void *key)
|
|
{
|
|
struct blk_mq_hw_ctx *hctx = READ_ONCE(wait->private);
|
|
|
|
list_del_init(&wait->entry);
|
|
blk_mq_run_hw_queue(hctx, true);
|
|
return 1;
|
|
}
|
|
|
|
static int kyber_get_domain_token(struct kyber_queue_data *kqd,
|
|
struct kyber_hctx_data *khd,
|
|
struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
unsigned int sched_domain = khd->cur_domain;
|
|
struct sbitmap_queue *domain_tokens = &kqd->domain_tokens[sched_domain];
|
|
wait_queue_entry_t *wait = &khd->domain_wait[sched_domain];
|
|
struct sbq_wait_state *ws;
|
|
int nr;
|
|
|
|
nr = __sbitmap_queue_get(domain_tokens);
|
|
|
|
/*
|
|
* If we failed to get a domain token, make sure the hardware queue is
|
|
* run when one becomes available. Note that this is serialized on
|
|
* khd->lock, but we still need to be careful about the waker.
|
|
*/
|
|
if (nr < 0 && list_empty_careful(&wait->entry)) {
|
|
ws = sbq_wait_ptr(domain_tokens,
|
|
&khd->wait_index[sched_domain]);
|
|
khd->domain_ws[sched_domain] = ws;
|
|
add_wait_queue(&ws->wait, wait);
|
|
|
|
/*
|
|
* Try again in case a token was freed before we got on the wait
|
|
* queue.
|
|
*/
|
|
nr = __sbitmap_queue_get(domain_tokens);
|
|
}
|
|
|
|
/*
|
|
* If we got a token while we were on the wait queue, remove ourselves
|
|
* from the wait queue to ensure that all wake ups make forward
|
|
* progress. It's possible that the waker already deleted the entry
|
|
* between the !list_empty_careful() check and us grabbing the lock, but
|
|
* list_del_init() is okay with that.
|
|
*/
|
|
if (nr >= 0 && !list_empty_careful(&wait->entry)) {
|
|
ws = khd->domain_ws[sched_domain];
|
|
spin_lock_irq(&ws->wait.lock);
|
|
list_del_init(&wait->entry);
|
|
spin_unlock_irq(&ws->wait.lock);
|
|
}
|
|
|
|
return nr;
|
|
}
|
|
|
|
static struct request *
|
|
kyber_dispatch_cur_domain(struct kyber_queue_data *kqd,
|
|
struct kyber_hctx_data *khd,
|
|
struct blk_mq_hw_ctx *hctx,
|
|
bool *flushed)
|
|
{
|
|
struct list_head *rqs;
|
|
struct request *rq;
|
|
int nr;
|
|
|
|
rqs = &khd->rqs[khd->cur_domain];
|
|
rq = list_first_entry_or_null(rqs, struct request, queuelist);
|
|
|
|
/*
|
|
* If there wasn't already a pending request and we haven't flushed the
|
|
* software queues yet, flush the software queues and check again.
|
|
*/
|
|
if (!rq && !*flushed) {
|
|
kyber_flush_busy_ctxs(khd, hctx);
|
|
*flushed = true;
|
|
rq = list_first_entry_or_null(rqs, struct request, queuelist);
|
|
}
|
|
|
|
if (rq) {
|
|
nr = kyber_get_domain_token(kqd, khd, hctx);
|
|
if (nr >= 0) {
|
|
khd->batching++;
|
|
rq_set_domain_token(rq, nr);
|
|
list_del_init(&rq->queuelist);
|
|
return rq;
|
|
}
|
|
}
|
|
|
|
/* There were either no pending requests or no tokens. */
|
|
return NULL;
|
|
}
|
|
|
|
static struct request *kyber_dispatch_request(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data;
|
|
struct kyber_hctx_data *khd = hctx->sched_data;
|
|
bool flushed = false;
|
|
struct request *rq;
|
|
int i;
|
|
|
|
spin_lock(&khd->lock);
|
|
|
|
/*
|
|
* First, if we are still entitled to batch, try to dispatch a request
|
|
* from the batch.
|
|
*/
|
|
if (khd->batching < kyber_batch_size[khd->cur_domain]) {
|
|
rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
|
|
if (rq)
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* Either,
|
|
* 1. We were no longer entitled to a batch.
|
|
* 2. The domain we were batching didn't have any requests.
|
|
* 3. The domain we were batching was out of tokens.
|
|
*
|
|
* Start another batch. Note that this wraps back around to the original
|
|
* domain if no other domains have requests or tokens.
|
|
*/
|
|
khd->batching = 0;
|
|
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
|
|
if (khd->cur_domain == KYBER_NUM_DOMAINS - 1)
|
|
khd->cur_domain = 0;
|
|
else
|
|
khd->cur_domain++;
|
|
|
|
rq = kyber_dispatch_cur_domain(kqd, khd, hctx, &flushed);
|
|
if (rq)
|
|
goto out;
|
|
}
|
|
|
|
rq = NULL;
|
|
out:
|
|
spin_unlock(&khd->lock);
|
|
return rq;
|
|
}
|
|
|
|
static bool kyber_has_work(struct blk_mq_hw_ctx *hctx)
|
|
{
|
|
struct kyber_hctx_data *khd = hctx->sched_data;
|
|
int i;
|
|
|
|
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
|
|
if (!list_empty_careful(&khd->rqs[i]))
|
|
return true;
|
|
}
|
|
return sbitmap_any_bit_set(&hctx->ctx_map);
|
|
}
|
|
|
|
#define KYBER_LAT_SHOW_STORE(op) \
|
|
static ssize_t kyber_##op##_lat_show(struct elevator_queue *e, \
|
|
char *page) \
|
|
{ \
|
|
struct kyber_queue_data *kqd = e->elevator_data; \
|
|
\
|
|
return sprintf(page, "%llu\n", kqd->op##_lat_nsec); \
|
|
} \
|
|
\
|
|
static ssize_t kyber_##op##_lat_store(struct elevator_queue *e, \
|
|
const char *page, size_t count) \
|
|
{ \
|
|
struct kyber_queue_data *kqd = e->elevator_data; \
|
|
unsigned long long nsec; \
|
|
int ret; \
|
|
\
|
|
ret = kstrtoull(page, 10, &nsec); \
|
|
if (ret) \
|
|
return ret; \
|
|
\
|
|
kqd->op##_lat_nsec = nsec; \
|
|
\
|
|
return count; \
|
|
}
|
|
KYBER_LAT_SHOW_STORE(read);
|
|
KYBER_LAT_SHOW_STORE(write);
|
|
#undef KYBER_LAT_SHOW_STORE
|
|
|
|
#define KYBER_LAT_ATTR(op) __ATTR(op##_lat_nsec, 0644, kyber_##op##_lat_show, kyber_##op##_lat_store)
|
|
static struct elv_fs_entry kyber_sched_attrs[] = {
|
|
KYBER_LAT_ATTR(read),
|
|
KYBER_LAT_ATTR(write),
|
|
__ATTR_NULL
|
|
};
|
|
#undef KYBER_LAT_ATTR
|
|
|
|
#ifdef CONFIG_BLK_DEBUG_FS
|
|
#define KYBER_DEBUGFS_DOMAIN_ATTRS(domain, name) \
|
|
static int kyber_##name##_tokens_show(void *data, struct seq_file *m) \
|
|
{ \
|
|
struct request_queue *q = data; \
|
|
struct kyber_queue_data *kqd = q->elevator->elevator_data; \
|
|
\
|
|
sbitmap_queue_show(&kqd->domain_tokens[domain], m); \
|
|
return 0; \
|
|
} \
|
|
\
|
|
static void *kyber_##name##_rqs_start(struct seq_file *m, loff_t *pos) \
|
|
__acquires(&khd->lock) \
|
|
{ \
|
|
struct blk_mq_hw_ctx *hctx = m->private; \
|
|
struct kyber_hctx_data *khd = hctx->sched_data; \
|
|
\
|
|
spin_lock(&khd->lock); \
|
|
return seq_list_start(&khd->rqs[domain], *pos); \
|
|
} \
|
|
\
|
|
static void *kyber_##name##_rqs_next(struct seq_file *m, void *v, \
|
|
loff_t *pos) \
|
|
{ \
|
|
struct blk_mq_hw_ctx *hctx = m->private; \
|
|
struct kyber_hctx_data *khd = hctx->sched_data; \
|
|
\
|
|
return seq_list_next(v, &khd->rqs[domain], pos); \
|
|
} \
|
|
\
|
|
static void kyber_##name##_rqs_stop(struct seq_file *m, void *v) \
|
|
__releases(&khd->lock) \
|
|
{ \
|
|
struct blk_mq_hw_ctx *hctx = m->private; \
|
|
struct kyber_hctx_data *khd = hctx->sched_data; \
|
|
\
|
|
spin_unlock(&khd->lock); \
|
|
} \
|
|
\
|
|
static const struct seq_operations kyber_##name##_rqs_seq_ops = { \
|
|
.start = kyber_##name##_rqs_start, \
|
|
.next = kyber_##name##_rqs_next, \
|
|
.stop = kyber_##name##_rqs_stop, \
|
|
.show = blk_mq_debugfs_rq_show, \
|
|
}; \
|
|
\
|
|
static int kyber_##name##_waiting_show(void *data, struct seq_file *m) \
|
|
{ \
|
|
struct blk_mq_hw_ctx *hctx = data; \
|
|
struct kyber_hctx_data *khd = hctx->sched_data; \
|
|
wait_queue_entry_t *wait = &khd->domain_wait[domain]; \
|
|
\
|
|
seq_printf(m, "%d\n", !list_empty_careful(&wait->entry)); \
|
|
return 0; \
|
|
}
|
|
KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_READ, read)
|
|
KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_SYNC_WRITE, sync_write)
|
|
KYBER_DEBUGFS_DOMAIN_ATTRS(KYBER_OTHER, other)
|
|
#undef KYBER_DEBUGFS_DOMAIN_ATTRS
|
|
|
|
static int kyber_async_depth_show(void *data, struct seq_file *m)
|
|
{
|
|
struct request_queue *q = data;
|
|
struct kyber_queue_data *kqd = q->elevator->elevator_data;
|
|
|
|
seq_printf(m, "%u\n", kqd->async_depth);
|
|
return 0;
|
|
}
|
|
|
|
static int kyber_cur_domain_show(void *data, struct seq_file *m)
|
|
{
|
|
struct blk_mq_hw_ctx *hctx = data;
|
|
struct kyber_hctx_data *khd = hctx->sched_data;
|
|
|
|
switch (khd->cur_domain) {
|
|
case KYBER_READ:
|
|
seq_puts(m, "READ\n");
|
|
break;
|
|
case KYBER_SYNC_WRITE:
|
|
seq_puts(m, "SYNC_WRITE\n");
|
|
break;
|
|
case KYBER_OTHER:
|
|
seq_puts(m, "OTHER\n");
|
|
break;
|
|
default:
|
|
seq_printf(m, "%u\n", khd->cur_domain);
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int kyber_batching_show(void *data, struct seq_file *m)
|
|
{
|
|
struct blk_mq_hw_ctx *hctx = data;
|
|
struct kyber_hctx_data *khd = hctx->sched_data;
|
|
|
|
seq_printf(m, "%u\n", khd->batching);
|
|
return 0;
|
|
}
|
|
|
|
#define KYBER_QUEUE_DOMAIN_ATTRS(name) \
|
|
{#name "_tokens", 0400, kyber_##name##_tokens_show}
|
|
static const struct blk_mq_debugfs_attr kyber_queue_debugfs_attrs[] = {
|
|
KYBER_QUEUE_DOMAIN_ATTRS(read),
|
|
KYBER_QUEUE_DOMAIN_ATTRS(sync_write),
|
|
KYBER_QUEUE_DOMAIN_ATTRS(other),
|
|
{"async_depth", 0400, kyber_async_depth_show},
|
|
{},
|
|
};
|
|
#undef KYBER_QUEUE_DOMAIN_ATTRS
|
|
|
|
#define KYBER_HCTX_DOMAIN_ATTRS(name) \
|
|
{#name "_rqs", 0400, .seq_ops = &kyber_##name##_rqs_seq_ops}, \
|
|
{#name "_waiting", 0400, kyber_##name##_waiting_show}
|
|
static const struct blk_mq_debugfs_attr kyber_hctx_debugfs_attrs[] = {
|
|
KYBER_HCTX_DOMAIN_ATTRS(read),
|
|
KYBER_HCTX_DOMAIN_ATTRS(sync_write),
|
|
KYBER_HCTX_DOMAIN_ATTRS(other),
|
|
{"cur_domain", 0400, kyber_cur_domain_show},
|
|
{"batching", 0400, kyber_batching_show},
|
|
{},
|
|
};
|
|
#undef KYBER_HCTX_DOMAIN_ATTRS
|
|
#endif
|
|
|
|
static struct elevator_type kyber_sched = {
|
|
.ops.mq = {
|
|
.init_sched = kyber_init_sched,
|
|
.exit_sched = kyber_exit_sched,
|
|
.init_hctx = kyber_init_hctx,
|
|
.exit_hctx = kyber_exit_hctx,
|
|
.limit_depth = kyber_limit_depth,
|
|
.prepare_request = kyber_prepare_request,
|
|
.finish_request = kyber_finish_request,
|
|
.completed_request = kyber_completed_request,
|
|
.dispatch_request = kyber_dispatch_request,
|
|
.has_work = kyber_has_work,
|
|
},
|
|
.uses_mq = true,
|
|
#ifdef CONFIG_BLK_DEBUG_FS
|
|
.queue_debugfs_attrs = kyber_queue_debugfs_attrs,
|
|
.hctx_debugfs_attrs = kyber_hctx_debugfs_attrs,
|
|
#endif
|
|
.elevator_attrs = kyber_sched_attrs,
|
|
.elevator_name = "kyber",
|
|
.elevator_owner = THIS_MODULE,
|
|
};
|
|
|
|
static int __init kyber_init(void)
|
|
{
|
|
return elv_register(&kyber_sched);
|
|
}
|
|
|
|
static void __exit kyber_exit(void)
|
|
{
|
|
elv_unregister(&kyber_sched);
|
|
}
|
|
|
|
module_init(kyber_init);
|
|
module_exit(kyber_exit);
|
|
|
|
MODULE_AUTHOR("Omar Sandoval");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_DESCRIPTION("Kyber I/O scheduler");
|