Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 25bc6b07 authored by Vivek Goyal's avatar Vivek Goyal Committed by Jens Axboe
Browse files

blkio: Introduce per cfq group weights and vdisktime calculations 



o Bring in the per cfq group weight and how vdisktime is calculated for the
  group. Also bring in the functionality of updating the min_vdisktime of
  the group service tree.

Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 31e4c28d

block/Kconfig.iosched

+8 −1
Original line number Diff line number Diff line
@@ -23,7 +23,6 @@ config IOSCHED_DEADLINE 


config IOSCHED_CFQ

	tristate "CFQ I/O scheduler"

	select BLK_CGROUP

	default y

	---help---

	  The CFQ I/O scheduler tries to distribute bandwidth equally
@@ -33,6 +32,14 @@ config IOSCHED_CFQ 


	  This is the default I/O scheduler.



config CFQ_GROUP_IOSCHED

	bool "CFQ Group Scheduling support"

	depends on IOSCHED_CFQ && CGROUPS

	select BLK_CGROUP

	default n

	---help---

	  Enable group IO scheduling in CFQ.



choice

	prompt "Default I/O scheduler"

	default DEFAULT_CFQ

block/cfq-iosched.c

+61 −1
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/rbtree.h>

#include <linux/ioprio.h>

#include <linux/blktrace_api.h>

#include "blk-cgroup.h"



/*

 * tunables
@@ -49,6 +50,7 @@ static const int cfq_hist_divisor = 4; 


#define CFQ_SLICE_SCALE		(5)

#define CFQ_HW_QUEUE_MIN	(5)

#define CFQ_SERVICE_SHIFT       12



#define RQ_CIC(rq)		\

	((struct cfq_io_context *) (rq)->elevator_private)
@@ -79,6 +81,7 @@ struct cfq_rb_root { 
	struct rb_node *left;

	unsigned count;

	u64 min_vdisktime;

	struct rb_node *active;

};

#define CFQ_RB_ROOT	(struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
@@ -163,6 +166,7 @@ struct cfq_group { 


	/* group service_tree key */

	u64 vdisktime;

	unsigned int weight;

	bool on_st;



	/* number of cfqq currently on this group */
@@ -434,6 +438,51 @@ cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) 
	return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);

}



static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)

{

	u64 d = delta << CFQ_SERVICE_SHIFT;



	d = d * BLKIO_WEIGHT_DEFAULT;

	do_div(d, cfqg->weight);

	return d;

}



static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)

{

	s64 delta = (s64)(vdisktime - min_vdisktime);

	if (delta > 0)

		min_vdisktime = vdisktime;



	return min_vdisktime;

}



static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)

{

	s64 delta = (s64)(vdisktime - min_vdisktime);

	if (delta < 0)

		min_vdisktime = vdisktime;



	return min_vdisktime;

}



static void update_min_vdisktime(struct cfq_rb_root *st)

{

	u64 vdisktime = st->min_vdisktime;

	struct cfq_group *cfqg;



	if (st->active) {

		cfqg = rb_entry_cfqg(st->active);

		vdisktime = cfqg->vdisktime;

	}



	if (st->left) {

		cfqg = rb_entry_cfqg(st->left);

		vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);

	}



	st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);

}



/*

 * get averaged number of queues of RT/BE priority.

 * average is updated, with a formula that gives more weight to higher numbers,
@@ -734,8 +783,12 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg) 
{

	struct cfq_rb_root *st = &cfqd->grp_service_tree;



	if (st->active == &cfqg->rb_node)

		st->active = NULL;



	BUG_ON(cfqg->nr_cfqq < 1);

	cfqg->nr_cfqq--;



	/* If there are other cfq queues under this group, don't delete it */

	if (cfqg->nr_cfqq)

		return;
@@ -1654,10 +1707,14 @@ static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) 
static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)

{

	struct cfq_rb_root *st = &cfqd->grp_service_tree;

	struct cfq_group *cfqg;



	if (RB_EMPTY_ROOT(&st->rb))

		return NULL;

	return cfq_rb_first_group(st);

	cfqg = cfq_rb_first_group(st);

	st->active = &cfqg->rb_node;

	update_min_vdisktime(st);

	return cfqg;

}



static void cfq_choose_cfqg(struct cfq_data *cfqd)
@@ -3150,6 +3207,9 @@ static void *cfq_init_queue(struct request_queue *q) 
		*st = CFQ_RB_ROOT;

	RB_CLEAR_NODE(&cfqg->rb_node);



	/* Give preference to root group over other groups */

	cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;



	/*

	 * Not strictly needed (since RB_ROOT just clears the node and we

	 * zeroed cfqd on alloc), but better be safe in case someone decides