block: add zen IO scheduler
Squash merge and add zen v2 tunables Signed-off-by: engstk <eng.stk@sapo.pt>
This commit is contained in:
Brandon Berhent
parent
53505bd5fc
commit
d167bc5324
@ -40,6 +40,13 @@ config CFQ_GROUP_IOSCHED
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---help---
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Enable group IO scheduling in CFQ.
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config IOSCHED_ZEN
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tristate "Zen I/O scheduler"
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default n
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---help---
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FCFS, dispatches are back-inserted, deadlines ensure fairness.
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Should work best with devices where there is no travel delay.
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choice
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prompt "Default I/O scheduler"
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@ -54,6 +61,9 @@ choice
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config DEFAULT_CFQ
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bool "CFQ" if IOSCHED_CFQ=y
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config DEFAULT_ZEN
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bool "ZEN" if IOSCHED_ZEN=y
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config DEFAULT_NOOP
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bool "No-op"
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@ -63,6 +73,7 @@ config DEFAULT_IOSCHED
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string
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default "deadline" if DEFAULT_DEADLINE
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default "cfq" if DEFAULT_CFQ
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default "zen" if DEFAULT_ZEN
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default "noop" if DEFAULT_NOOP
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config MQ_IOSCHED_DEADLINE
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@ -21,6 +21,7 @@ obj-$(CONFIG_BLK_CGROUP_IOLATENCY) += blk-iolatency.o
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obj-$(CONFIG_IOSCHED_NOOP) += noop-iosched.o
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obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
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obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o
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obj-$(CONFIG_IOSCHED_ZEN) += zen-iosched.o
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obj-$(CONFIG_MQ_IOSCHED_DEADLINE) += mq-deadline.o
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obj-$(CONFIG_MQ_IOSCHED_KYBER) += kyber-iosched.o
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bfq-y := bfq-iosched.o bfq-wf2q.o bfq-cgroup.o
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292
block/zen-iosched.c
Normal file
292
block/zen-iosched.c
Normal file
@ -0,0 +1,292 @@
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/*
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* Zen IO scheduler
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* Primarily based on Noop, deadline, and SIO IO schedulers.
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*
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* Copyright (C) 2012 Brandon Berhent <bbedward@gmail.com>
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* (C) 2014 LoungeKatt <twistedumbrella@gmail.com>
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* (c) 2015 Fixes to stop crashing on 3.10 by Matthew Alex <matthewalex@outlook.com>
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*
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* FCFS, dispatches are back-inserted, deadlines ensure fairness.
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* Should work best with devices where there is no travel delay.
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*/
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#include <linux/bio.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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enum zen_data_dir { ASYNC, SYNC };
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static const int sync_expire = HZ / 2; /* max time before a sync is submitted. */
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static const int async_expire = 5 * HZ; /* ditto for async, these limits are SOFT! */
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static const int fifo_batch = 16;
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struct zen_data {
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/* Runtime Data */
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/* Requests are only present on fifo_list */
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struct list_head fifo_list[2];
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unsigned int batching; /* number of sequential requests made */
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/* tunables */
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int fifo_expire[2];
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int fifo_batch;
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};
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static inline struct zen_data *
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zen_get_data(struct request_queue *q) {
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return q->elevator->elevator_data;
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}
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static void zen_dispatch(struct zen_data *, struct request *);
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static void
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zen_merged_requests(struct request_queue *q, struct request *req,
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struct request *next)
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{
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/*
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* if next expires before rq, assign its expire time to arq
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* and move into next position (next will be deleted) in fifo
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*/
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if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
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if (time_before(rq_fifo_time(next), rq_fifo_time(req))) {
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list_move(&req->queuelist, &next->queuelist);
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rq_set_fifo_time(req, rq_fifo_time(next));
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}
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}
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/* next request is gone */
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rq_fifo_clear(next);
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}
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static void zen_add_request(struct request_queue *q, struct request *rq)
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{
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struct zen_data *zdata = zen_get_data(q);
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const int sync = rq_is_sync(rq);
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if (zdata->fifo_expire[sync]) {
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rq_set_fifo_time(rq, jiffies + zdata->fifo_expire[sync]);
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list_add_tail(&rq->queuelist, &zdata->fifo_list[sync]);
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}
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}
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static void zen_dispatch(struct zen_data *zdata, struct request *rq)
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{
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/* Remove request from list and dispatch it */
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rq_fifo_clear(rq);
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elv_dispatch_add_tail(rq->q, rq);
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/* Increment # of sequential requests */
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zdata->batching++;
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}
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/*
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* get the first expired request in direction ddir
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*/
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static struct request *
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zen_expired_request(struct zen_data *zdata, int ddir)
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{
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struct request *rq;
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if (list_empty(&zdata->fifo_list[ddir]))
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return NULL;
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rq = rq_entry_fifo(zdata->fifo_list[ddir].next);
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if (time_after_eq(jiffies, rq_fifo_time(rq)))
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return rq;
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return NULL;
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}
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/*
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* zen_check_fifo returns 0 if there are no expired requests on the fifo,
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* otherwise it returns the next expired request
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*/
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static struct request *
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zen_check_fifo(struct zen_data *zdata)
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{
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struct request *rq_sync = zen_expired_request(zdata, SYNC);
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struct request *rq_async = zen_expired_request(zdata, ASYNC);
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if (rq_async && rq_sync) {
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if (time_after(rq_fifo_time(rq_async), rq_fifo_time(rq_sync)))
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return rq_sync;
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} else if (rq_sync) {
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return rq_sync;
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} else if (rq_async) {
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return rq_async;
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}
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return 0;
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}
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static struct request *
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zen_choose_request(struct zen_data *zdata)
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{
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/*
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* Retrieve request from available fifo list.
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* Synchronous requests have priority over asynchronous.
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*/
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if (!list_empty(&zdata->fifo_list[SYNC]))
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return rq_entry_fifo(zdata->fifo_list[SYNC].next);
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if (!list_empty(&zdata->fifo_list[ASYNC]))
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return rq_entry_fifo(zdata->fifo_list[ASYNC].next);
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return NULL;
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}
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static int zen_dispatch_requests(struct request_queue *q, int force)
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{
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struct zen_data *zdata = zen_get_data(q);
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struct request *rq = NULL;
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/* Check for and issue expired requests */
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if (zdata->batching > zdata->fifo_batch) {
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zdata->batching = 0;
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rq = zen_check_fifo(zdata);
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}
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if (!rq) {
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rq = zen_choose_request(zdata);
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if (!rq)
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return 0;
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}
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zen_dispatch(zdata, rq);
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return 1;
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}
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static int zen_init_queue(struct request_queue *q, struct elevator_type *e)
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{
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struct zen_data *zdata;
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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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zdata = kmalloc_node(sizeof(*zdata), GFP_KERNEL, q->node);
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if (!zdata) {
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kobject_put(&eq->kobj);
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return -ENOMEM;
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}
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eq->elevator_data = zdata;
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spin_lock_irq(q->queue_lock);
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q->elevator = eq;
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spin_unlock_irq(q->queue_lock);
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INIT_LIST_HEAD(&zdata->fifo_list[SYNC]);
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INIT_LIST_HEAD(&zdata->fifo_list[ASYNC]);
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zdata->fifo_expire[SYNC] = sync_expire;
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zdata->fifo_expire[ASYNC] = async_expire;
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zdata->fifo_batch = fifo_batch;
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return 0;
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}
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static void zen_exit_queue(struct elevator_queue *e)
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{
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struct zen_data *zdata = e->elevator_data;
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BUG_ON(!list_empty(&zdata->fifo_list[SYNC]));
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BUG_ON(!list_empty(&zdata->fifo_list[ASYNC]));
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kfree(zdata);
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}
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/* Sysfs */
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static ssize_t
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zen_var_show(int var, char *page)
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{
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return sprintf(page, "%d\n", var);
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}
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static ssize_t
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zen_var_store(int *var, const char *page, size_t count)
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{
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*var = simple_strtol(page, NULL, 10);
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return count;
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}
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#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
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static ssize_t __FUNC(struct elevator_queue *e, char *page) \
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{ \
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struct zen_data *zdata = e->elevator_data; \
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int __data = __VAR; \
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if (__CONV) \
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__data = jiffies_to_msecs(__data); \
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return zen_var_show(__data, (page)); \
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}
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SHOW_FUNCTION(zen_sync_expire_show, zdata->fifo_expire[SYNC], 1);
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SHOW_FUNCTION(zen_async_expire_show, zdata->fifo_expire[ASYNC], 1);
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SHOW_FUNCTION(zen_fifo_batch_show, zdata->fifo_batch, 0);
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#undef SHOW_FUNCTION
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#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
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static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
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{ \
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struct zen_data *zdata = e->elevator_data; \
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int __data; \
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int ret = zen_var_store(&__data, (page), count); \
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if (__data < (MIN)) \
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__data = (MIN); \
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else if (__data > (MAX)) \
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__data = (MAX); \
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if (__CONV) \
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*(__PTR) = msecs_to_jiffies(__data); \
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else \
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*(__PTR) = __data; \
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return ret; \
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}
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STORE_FUNCTION(zen_sync_expire_store, &zdata->fifo_expire[SYNC], 0, INT_MAX, 1);
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STORE_FUNCTION(zen_async_expire_store, &zdata->fifo_expire[ASYNC], 0, INT_MAX, 1);
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STORE_FUNCTION(zen_fifo_batch_store, &zdata->fifo_batch, 0, INT_MAX, 0);
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#undef STORE_FUNCTION
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#define DD_ATTR(name) \
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__ATTR(name, S_IRUGO|S_IWUSR, zen_##name##_show, \
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zen_##name##_store)
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static struct elv_fs_entry zen_attrs[] = {
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DD_ATTR(sync_expire),
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DD_ATTR(async_expire),
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DD_ATTR(fifo_batch),
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__ATTR_NULL
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};
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static struct elevator_type iosched_zen = {
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.ops = {
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.elevator_merge_req_fn = zen_merged_requests,
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.elevator_dispatch_fn = zen_dispatch_requests,
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.elevator_add_req_fn = zen_add_request,
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.elevator_former_req_fn = elv_rb_former_request,
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.elevator_latter_req_fn = elv_rb_latter_request,
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.elevator_init_fn = zen_init_queue,
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.elevator_exit_fn = zen_exit_queue,
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},
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.elevator_attrs = zen_attrs,
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.elevator_name = "zen",
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.elevator_owner = THIS_MODULE,
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};
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static int __init zen_init(void)
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{
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return elv_register(&iosched_zen);
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}
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static void __exit zen_exit(void)
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{
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elv_unregister(&iosched_zen);
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}
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module_init(zen_init);
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module_exit(zen_exit);
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MODULE_AUTHOR("Brandon Berhent");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Zen IO scheduler");
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MODULE_VERSION("2.0");
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