linux/block/kyber-iosched.c
Jianchao Wang a6088845c2 block: kyber: make kyber more friendly with merging
Currently, kyber is very unfriendly with merging. kyber depends
on ctx rq_list to do merging, however, most of time, it will not
leave any requests in ctx rq_list. This is because even if tokens
of one domain is used up, kyber will try to dispatch requests
from other domain and flush the rq_list there.

To improve this, we setup kyber_ctx_queue (kcq) which is similar
with ctx, but it has rq_lists for different domain and build same
mapping between kcq and khd as the ctx & hctx. Then we could merge,
insert and dispatch for different domains separately. At the same
time, only flush the rq_list of kcq when get domain token successfully.
Then if one domain token is used up, the requests could be left in
the rq_list of that domain and maybe merged with following io.

Following is my test result on machine with 8 cores and NVMe card
INTEL SSDPEKKR128G7

fio size=256m ioengine=libaio iodepth=64 direct=1 numjobs=8
seq/random
+------+---------------------------------------------------------------+
|patch?| bw(MB/s) |   iops    | slat(usec) |    clat(usec)   |  merge  |
+----------------------------------------------------------------------+
| w/o  |  606/612 | 151k/153k |  6.89/7.03 | 3349.21/3305.40 |   0/0   |
+----------------------------------------------------------------------+
| w/   | 1083/616 | 277k/154k |  4.93/6.95 | 1830.62/3279.95 | 223k/3k |
+----------------------------------------------------------------------+
When set numjobs to 16, the bw and iops could reach 1662MB/s and 425k
on my platform.

Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-30 10:47:40 -06:00

996 lines
25 KiB
C

/*
* The Kyber I/O scheduler. Controls latency by throttling queue depths using
* scalable techniques.
*
* Copyright (C) 2017 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/elevator.h>
#include <linux/module.h>
#include <linux/sbitmap.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-debugfs.h"
#include "blk-mq-sched.h"
#include "blk-mq-tag.h"
#include "blk-stat.h"
/* Scheduling domains. */
enum {
KYBER_READ,
KYBER_SYNC_WRITE,
KYBER_OTHER, /* Async writes, discard, etc. */
KYBER_NUM_DOMAINS,
};
enum {
KYBER_MIN_DEPTH = 256,
/*
* In order to prevent starvation of synchronous requests by a flood of
* asynchronous requests, we reserve 25% of requests for synchronous
* operations.
*/
KYBER_ASYNC_PERCENT = 75,
};
/*
* Initial device-wide depths for each scheduling domain.
*
* Even for fast devices with lots of tags like NVMe, you can saturate
* the device with only a fraction of the maximum possible queue depth.
* So, we cap these to a reasonable value.
*/
static const unsigned int kyber_depth[] = {
[KYBER_READ] = 256,
[KYBER_SYNC_WRITE] = 128,
[KYBER_OTHER] = 64,
};
/*
* Scheduling domain batch sizes. We favor reads.
*/
static const unsigned int kyber_batch_size[] = {
[KYBER_READ] = 16,
[KYBER_SYNC_WRITE] = 8,
[KYBER_OTHER] = 8,
};
/*
* There is a same mapping between ctx & hctx and kcq & khd,
* we use request->mq_ctx->index_hw to index the kcq in khd.
*/
struct kyber_ctx_queue {
/*
* Used to ensure operations on rq_list and kcq_map to be an atmoic one.
* Also protect the rqs on rq_list when merge.
*/
spinlock_t lock;
struct list_head rq_list[KYBER_NUM_DOMAINS];
} ____cacheline_aligned_in_smp;
struct kyber_queue_data {
struct request_queue *q;
struct blk_stat_callback *cb;
/*
* The device is divided into multiple scheduling domains based on the
* request type. Each domain has a fixed number of in-flight requests of
* that type device-wide, limited by these tokens.
*/
struct sbitmap_queue domain_tokens[KYBER_NUM_DOMAINS];
/*
* Async request percentage, converted to per-word depth for
* sbitmap_get_shallow().
*/
unsigned int async_depth;
/* Target latencies in nanoseconds. */
u64 read_lat_nsec, write_lat_nsec;
};
struct kyber_hctx_data {
spinlock_t lock;
struct list_head rqs[KYBER_NUM_DOMAINS];
unsigned int cur_domain;
unsigned int batching;
struct kyber_ctx_queue *kcqs;
struct sbitmap kcq_map[KYBER_NUM_DOMAINS];
wait_queue_entry_t domain_wait[KYBER_NUM_DOMAINS];
struct sbq_wait_state *domain_ws[KYBER_NUM_DOMAINS];
atomic_t wait_index[KYBER_NUM_DOMAINS];
};
static int kyber_domain_wake(wait_queue_entry_t *wait, unsigned mode, int flags,
void *key);
static unsigned int kyber_sched_domain(unsigned int op)
{
if ((op & REQ_OP_MASK) == REQ_OP_READ)
return KYBER_READ;
else if ((op & REQ_OP_MASK) == REQ_OP_WRITE && op_is_sync(op))
return KYBER_SYNC_WRITE;
else
return KYBER_OTHER;
}
enum {
NONE = 0,
GOOD = 1,
GREAT = 2,
BAD = -1,
AWFUL = -2,
};
#define IS_GOOD(status) ((status) > 0)
#define IS_BAD(status) ((status) < 0)
static int kyber_lat_status(struct blk_stat_callback *cb,
unsigned int sched_domain, u64 target)
{
u64 latency;
if (!cb->stat[sched_domain].nr_samples)
return NONE;
latency = cb->stat[sched_domain].mean;
if (latency >= 2 * target)
return AWFUL;
else if (latency > target)
return BAD;
else if (latency <= target / 2)
return GREAT;
else /* (latency <= target) */
return GOOD;
}
/*
* Adjust the read or synchronous write depth given the status of reads and
* writes. The goal is that the latencies of the two domains are fair (i.e., if
* one is good, then the other is good).
*/
static void kyber_adjust_rw_depth(struct kyber_queue_data *kqd,
unsigned int sched_domain, int this_status,
int other_status)
{
unsigned int orig_depth, depth;
/*
* If this domain had no samples, or reads and writes are both good or
* both bad, don't adjust the depth.
*/
if (this_status == NONE ||
(IS_GOOD(this_status) && IS_GOOD(other_status)) ||
(IS_BAD(this_status) && IS_BAD(other_status)))
return;
orig_depth = depth = kqd->domain_tokens[sched_domain].sb.depth;
if (other_status == NONE) {
depth++;
} else {
switch (this_status) {
case GOOD:
if (other_status == AWFUL)
depth -= max(depth / 4, 1U);
else
depth -= max(depth / 8, 1U);
break;
case GREAT:
if (other_status == AWFUL)
depth /= 2;
else
depth -= max(depth / 4, 1U);
break;
case BAD:
depth++;
break;
case AWFUL:
if (other_status == GREAT)
depth += 2;
else
depth++;
break;
}
}
depth = clamp(depth, 1U, kyber_depth[sched_domain]);
if (depth != orig_depth)
sbitmap_queue_resize(&kqd->domain_tokens[sched_domain], depth);
}
/*
* Adjust the depth of other requests given the status of reads and synchronous
* writes. As long as either domain is doing fine, we don't throttle, but if
* both domains are doing badly, we throttle heavily.
*/
static void kyber_adjust_other_depth(struct kyber_queue_data *kqd,
int read_status, int write_status,
bool have_samples)
{
unsigned int orig_depth, depth;
int status;
orig_depth = depth = kqd->domain_tokens[KYBER_OTHER].sb.depth;
if (read_status == NONE && write_status == NONE) {
depth += 2;
} else if (have_samples) {
if (read_status == NONE)
status = write_status;
else if (write_status == NONE)
status = read_status;
else
status = max(read_status, write_status);
switch (status) {
case GREAT:
depth += 2;
break;
case GOOD:
depth++;
break;
case BAD:
depth -= max(depth / 4, 1U);
break;
case AWFUL:
depth /= 2;
break;
}
}
depth = clamp(depth, 1U, kyber_depth[KYBER_OTHER]);
if (depth != orig_depth)
sbitmap_queue_resize(&kqd->domain_tokens[KYBER_OTHER], depth);
}
/*
* Apply heuristics for limiting queue depths based on gathered latency
* statistics.
*/
static void kyber_stat_timer_fn(struct blk_stat_callback *cb)
{
struct kyber_queue_data *kqd = cb->data;
int read_status, write_status;
read_status = kyber_lat_status(cb, KYBER_READ, kqd->read_lat_nsec);
write_status = kyber_lat_status(cb, KYBER_SYNC_WRITE, kqd->write_lat_nsec);
kyber_adjust_rw_depth(kqd, KYBER_READ, read_status, write_status);
kyber_adjust_rw_depth(kqd, KYBER_SYNC_WRITE, write_status, read_status);
kyber_adjust_other_depth(kqd, read_status, write_status,
cb->stat[KYBER_OTHER].nr_samples != 0);
/*
* Continue monitoring latencies if we aren't hitting the targets or
* we're still throttling other requests.
*/
if (!blk_stat_is_active(kqd->cb) &&
((IS_BAD(read_status) || IS_BAD(write_status) ||
kqd->domain_tokens[KYBER_OTHER].sb.depth < kyber_depth[KYBER_OTHER])))
blk_stat_activate_msecs(kqd->cb, 100);
}
static unsigned int kyber_sched_tags_shift(struct kyber_queue_data *kqd)
{
/*
* All of the hardware queues have the same depth, so we can just grab
* the shift of the first one.
*/
return kqd->q->queue_hw_ctx[0]->sched_tags->bitmap_tags.sb.shift;
}
static int kyber_bucket_fn(const struct request *rq)
{
return kyber_sched_domain(rq->cmd_flags);
}
static struct kyber_queue_data *kyber_queue_data_alloc(struct request_queue *q)
{
struct kyber_queue_data *kqd;
unsigned int max_tokens;
unsigned int shift;
int ret = -ENOMEM;
int i;
kqd = kmalloc_node(sizeof(*kqd), GFP_KERNEL, q->node);
if (!kqd)
goto err;
kqd->q = q;
kqd->cb = blk_stat_alloc_callback(kyber_stat_timer_fn, kyber_bucket_fn,
KYBER_NUM_DOMAINS, kqd);
if (!kqd->cb)
goto err_kqd;
/*
* The maximum number of tokens for any scheduling domain is at least
* the queue depth of a single hardware queue. If the hardware doesn't
* have many tags, still provide a reasonable number.
*/
max_tokens = max_t(unsigned int, q->tag_set->queue_depth,
KYBER_MIN_DEPTH);
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
WARN_ON(!kyber_depth[i]);
WARN_ON(!kyber_batch_size[i]);
ret = sbitmap_queue_init_node(&kqd->domain_tokens[i],
max_tokens, -1, false, GFP_KERNEL,
q->node);
if (ret) {
while (--i >= 0)
sbitmap_queue_free(&kqd->domain_tokens[i]);
goto err_cb;
}
sbitmap_queue_resize(&kqd->domain_tokens[i], kyber_depth[i]);
}
shift = kyber_sched_tags_shift(kqd);
kqd->async_depth = (1U << shift) * KYBER_ASYNC_PERCENT / 100U;
kqd->read_lat_nsec = 2000000ULL;
kqd->write_lat_nsec = 10000000ULL;
return kqd;
err_cb:
blk_stat_free_callback(kqd->cb);
err_kqd:
kfree(kqd);
err:
return ERR_PTR(ret);
}
static int kyber_init_sched(struct request_queue *q, struct elevator_type *e)
{
struct kyber_queue_data *kqd;
struct elevator_queue *eq;
eq = elevator_alloc(q, e);
if (!eq)
return -ENOMEM;
kqd = kyber_queue_data_alloc(q);
if (IS_ERR(kqd)) {
kobject_put(&eq->kobj);
return PTR_ERR(kqd);
}
eq->elevator_data = kqd;
q->elevator = eq;
blk_stat_add_callback(q, kqd->cb);
return 0;
}
static void kyber_exit_sched(struct elevator_queue *e)
{
struct kyber_queue_data *kqd = e->elevator_data;
struct request_queue *q = kqd->q;
int i;
blk_stat_remove_callback(q, kqd->cb);
for (i = 0; i < KYBER_NUM_DOMAINS; i++)
sbitmap_queue_free(&kqd->domain_tokens[i]);
blk_stat_free_callback(kqd->cb);
kfree(kqd);
}
static void kyber_ctx_queue_init(struct kyber_ctx_queue *kcq)
{
unsigned int i;
spin_lock_init(&kcq->lock);
for (i = 0; i < KYBER_NUM_DOMAINS; i++)
INIT_LIST_HEAD(&kcq->rq_list[i]);
}
static int kyber_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
struct kyber_queue_data *kqd = hctx->queue->elevator->elevator_data;
struct kyber_hctx_data *khd;
int i;
khd = kmalloc_node(sizeof(*khd), GFP_KERNEL, hctx->numa_node);
if (!khd)
return -ENOMEM;
khd->kcqs = kmalloc_array_node(hctx->nr_ctx,
sizeof(struct kyber_ctx_queue),
GFP_KERNEL, hctx->numa_node);
if (!khd->kcqs)
goto err_khd;
for (i = 0; i < hctx->nr_ctx; i++)
kyber_ctx_queue_init(&khd->kcqs[i]);
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
if (sbitmap_init_node(&khd->kcq_map[i], hctx->nr_ctx,
ilog2(8), GFP_KERNEL, hctx->numa_node)) {
while (--i >= 0)
sbitmap_free(&khd->kcq_map[i]);
goto err_kcqs;
}
}
spin_lock_init(&khd->lock);
for (i = 0; i < KYBER_NUM_DOMAINS; i++) {
INIT_LIST_HEAD(&khd->rqs[i]);
init_waitqueue_func_entry(&khd->domain_wait[i],
kyber_domain_wake);
khd->domain_wait[i].private = hctx;
INIT_LIST_HEAD(&khd->domain_wait[i].entry);
atomic_set(&khd->wait_index[i], 0);
}
khd->cur_domain = 0;
khd->batching = 0;
hctx->sched_data = khd;
sbitmap_queue_min_shallow_depth(&hctx->sched_tags->bitmap_tags,
kqd->async_depth);
return 0;
err_kcqs:
kfree(khd->kcqs);
err_khd:
kfree(khd);
return -ENOMEM;
}
static void kyber_exit_hctx(struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
{
struct kyber_hctx_data *khd = hctx->sched_data;
int i;
for (i = 0; i < KYBER_NUM_DOMAINS; i++)
sbitmap_free(&khd->kcq_map[i]);
kfree(khd->kcqs);
kfree(hctx->sched_data);
}
static int rq_get_domain_token(struct request *rq)
{
return (long)rq->elv.priv[0];
}
static void rq_set_domain_token(struct request *rq, int token)
{
rq->elv.priv[0] = (void *)(long)token;
}
static void rq_clear_domain_token(struct kyber_queue_data *kqd,
struct request *rq)
{
unsigned int sched_domain;
int nr;
nr = rq_get_domain_token(rq);
if (nr != -1) {
sched_domain = kyber_sched_domain(rq->cmd_flags);
sbitmap_queue_clear(&kqd->domain_tokens[sched_domain], nr,
rq->mq_ctx->cpu);
}
}
static void kyber_limit_depth(unsigned int op, struct blk_mq_alloc_data *data)
{
/*
* We use the scheduler tags as per-hardware queue queueing tokens.
* Async requests can be limited at this stage.
*/
if (!op_is_sync(op)) {
struct kyber_queue_data *kqd = data->q->elevator->elevator_data;
data->shallow_depth = kqd->async_depth;
}
}
static bool kyber_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
{
struct kyber_hctx_data *khd = hctx->sched_data;
struct blk_mq_ctx *ctx = blk_mq_get_ctx(hctx->queue);
struct kyber_ctx_queue *kcq = &khd->kcqs[ctx->index_hw];
unsigned int sched_domain = kyber_sched_domain(bio->bi_opf);
struct list_head *rq_list = &kcq->rq_list[sched_domain];
bool merged;
spin_lock(&kcq->lock);
merged = blk_mq_bio_list_merge(hctx->queue, rq_list, bio);
spin_unlock(&kcq->lock);
blk_mq_put_ctx(ctx);
return merged;
}
static void kyber_prepare_request(struct request *rq, struct bio *bio)
{
rq_set_domain_token(rq, -1);
}
static void kyber_insert_requests(struct blk_mq_hw_ctx *hctx,
struct list_head *rq_list, bool at_head)
{
struct kyber_hctx_data *khd = hctx->sched_data;
struct request *rq, *next;
list_for_each_entry_safe(rq, next, rq_list, queuelist) {
unsigned int sched_domain = kyber_sched_domain(rq->cmd_flags);
struct kyber_ctx_queue *kcq = &khd->kcqs[rq->mq_ctx->index_hw];
struct list_head *head = &kcq->rq_list[sched_domain];
spin_lock(&kcq->lock);
if (at_head)
list_move(&rq->queuelist, head);
else
list_move_tail(&rq->queuelist, head);
sbitmap_set_bit(&khd->kcq_map[sched_domain],
rq->mq_ctx->index_hw);
blk_mq_sched_request_inserted(rq);
spin_unlock(&kcq->lock);
}
}
static void kyber_finish_request(struct request *rq)
{
struct kyber_queue_data *kqd = rq->q->elevator->elevator_data;
rq_clear_domain_token(kqd, rq);
}
static void kyber_completed_request(struct request *rq)
{
struct request_queue *q = rq->q;
struct kyber_queue_data *kqd = q->elevator->elevator_data;
unsigned int sched_domain;
u64 now, latency, target;
/*
* Check if this request met our latency goal. If not, quickly gather
* some statistics and start throttling.
*/
sched_domain = kyber_sched_domain(rq->cmd_flags);
switch (sched_domain) {
case KYBER_READ:
target = kqd->read_lat_nsec;
break;
case KYBER_SYNC_WRITE:
target = kqd->write_lat_nsec;
break;
default:
return;
}
/* If we are already monitoring latencies, don't check again. */
if (blk_stat_is_active(kqd->cb))
return;
now = ktime_get_ns();
if (now < rq->io_start_time_ns)
return;
latency = now - rq->io_start_time_ns;
if (latency > target)
blk_stat_activate_msecs(kqd->cb, 10);
}
struct flush_kcq_data {
struct kyber_hctx_data *khd;
unsigned int sched_domain;
struct list_head *list;
};
static bool flush_busy_kcq(struct sbitmap *sb, unsigned int bitnr, void *data)
{
struct flush_kcq_data *flush_data = data;
struct kyber_ctx_queue *kcq = &flush_data->khd->kcqs[bitnr];
spin_lock(&kcq->lock);
list_splice_tail_init(&kcq->rq_list[flush_data->sched_domain],
flush_data->list);
sbitmap_clear_bit(sb, bitnr);
spin_unlock(&kcq->lock);
return true;
}
static void kyber_flush_busy_kcqs(struct kyber_hctx_data *khd,
unsigned int sched_domain,
struct list_head *list)
{
struct flush_kcq_data data = {
.khd = khd,
.sched_domain = sched_domain,
.list = list,
};
sbitmap_for_each_set(&khd->kcq_map[sched_domain],
flush_busy_kcq, &data);
}
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)
{
struct list_head *rqs;
struct request *rq;
int nr;
rqs = &khd->rqs[khd->cur_domain];
/*
* If we already have a flushed request, then we just need to get a
* token for it. Otherwise, if there are pending requests in the kcqs,
* flush the kcqs, but only if we can get a token. If not, we should
* leave the requests in the kcqs so that they can be merged. Note that
* khd->lock serializes the flushes, so if we observed any bit set in
* the kcq_map, we will always get a request.
*/
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;
}
} else if (sbitmap_any_bit_set(&khd->kcq_map[khd->cur_domain])) {
nr = kyber_get_domain_token(kqd, khd, hctx);
if (nr >= 0) {
kyber_flush_busy_kcqs(khd, khd->cur_domain, rqs);
rq = list_first_entry(rqs, struct request, queuelist);
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;
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);
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);
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]) ||
sbitmap_any_bit_set(&khd->kcq_map[i]))
return true;
}
return false;
}
#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,
.bio_merge = kyber_bio_merge,
.prepare_request = kyber_prepare_request,
.insert_requests = kyber_insert_requests,
.finish_request = kyber_finish_request,
.requeue_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");