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SmartisanOS_Kernel_Source/block/row-iosched.c at master · feiser2016/SmartisanOS_Kernel_Source · GitHub
feiser2016
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/*
* ROW (Read Over Write) I/O scheduler.
*
* Copyright (c) 2012-2013, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 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.
*/
/* See Documentation/block/row-iosched.txt */
#include
<linux/kernel.h>
#include
<linux/fs.h>
#include
<linux/blkdev.h>
#include
<linux/elevator.h>
#include
<linux/bio.h>
#include
<linux/module.h>
#include
<linux/slab.h>
#include
<linux/init.h>
#include
<linux/compiler.h>
#include
<linux/blktrace_api.h>
#include
<linux/hrtimer.h>
/*
* enum row_queue_prio - Priorities of the ROW queues
*
* This enum defines the priorities (and the number of queues)
* the requests will be distributed to. The higher priority -
* the bigger is the "bus time" (or the dispatch quantum) given
* to that queue.
* ROWQ_PRIO_HIGH_READ - is the higher priority queue.
*
*/
enum
row_queue_prio
{
ROWQ_PRIO_HIGH_READ
=
0
,
ROWQ_PRIO_HIGH_SWRITE
,
ROWQ_PRIO_REG_READ
,
ROWQ_PRIO_REG_SWRITE
,
ROWQ_PRIO_REG_WRITE
,
ROWQ_PRIO_LOW_READ
,
ROWQ_PRIO_LOW_SWRITE
,
ROWQ_MAX_PRIO
,
};
/*
* The following indexes define the distribution of ROW queues according to
* priorities. Each index defines the first queue in that priority group.
*/
#define
ROWQ_HIGH_PRIO_IDX
ROWQ_PRIO_HIGH_READ
#define
ROWQ_REG_PRIO_IDX
ROWQ_PRIO_REG_READ
#define
ROWQ_LOW_PRIO_IDX
ROWQ_PRIO_LOW_READ
/**
* struct row_queue_params - ROW queue parameters
* @idling_enabled: Flag indicating whether idling is enable on
* the queue
* @quantum: Number of requests to be dispatched from this queue
* in a dispatch cycle
* @is_urgent: Flags indicating whether the queue can notify on
* urgent requests
*
*/
struct
row_queue_params
{
bool
idling_enabled
;
int
quantum
;
bool
is_urgent
;
};
/*
* This array holds the default values of the different configurables
* for each ROW queue. Each row of the array holds the following values:
* {idling_enabled, quantum, is_urgent}
* Each row corresponds to a queue with the same index (according to
* enum row_queue_prio)
* Note: The quantums are valid inside their priority type. For example:
* For every 10 high priority read requests, 1 high priority sync
* write will be dispatched.
* For every 100 regular read requests 1 regular write request will
* be dispatched.
*/
static
const
struct
row_queue_params
row_queues_def
[]
=
{
/* idling_enabled, quantum, is_urgent */
{true,
10
, true},
/* ROWQ_PRIO_HIGH_READ */
{false,
1
, false},
/* ROWQ_PRIO_HIGH_SWRITE */
{true,
100
, true},
/* ROWQ_PRIO_REG_READ */
{false,
1
, false},
/* ROWQ_PRIO_REG_SWRITE */
{false,
1
, false},
/* ROWQ_PRIO_REG_WRITE */
{false,
1
, false},
/* ROWQ_PRIO_LOW_READ */
{false,
1
, false}
/* ROWQ_PRIO_LOW_SWRITE */
};
/* Default values for idling on read queues (in msec) */
#define
ROW_IDLE_TIME_MSEC
5
#define
ROW_READ_FREQ_MSEC
5
/**
* struct rowq_idling_data - parameters for idling on the queue
* @last_insert_time: time the last request was inserted
* to the queue
* @begin_idling: flag indicating wether we should idle
*
*/
struct
rowq_idling_data
{
ktime_t
last_insert_time
;
bool
begin_idling
;
};
/**
* struct row_queue - requests grouping structure
* @rdata: parent row_data structure
* @fifo: fifo of requests
* @prio: queue priority (enum row_queue_prio)
* @nr_dispatched: number of requests already dispatched in
* the current dispatch cycle
* @nr_req: number of requests in queue
* @dispatch quantum: number of requests this queue may
* dispatch in a dispatch cycle
* @idle_data: data for idling on queues
*
*/
struct
row_queue
{
struct
row_data
*
rdata
;
struct
list_head
fifo
;
enum
row_queue_prio
prio
;
unsigned
int
nr_dispatched
;
unsigned
int
nr_req
;
int
disp_quantum
;
/* used only for READ queues */
struct
rowq_idling_data
idle_data
;
};
/**
* struct idling_data - data for idling on empty rqueue
* @idle_time_ms: idling duration (msec)
* @freq_ms: min time between two requests that
* triger idling (msec)
* @hr_timer: idling timer
* @idle_work: the work to be scheduled when idling timer expires
* @idling_queue_idx: index of the queues we're idling on
*
*/
struct
idling_data
{
s64
idle_time_ms
;
s64
freq_ms
;
struct
hrtimer
hr_timer
;
struct
work_struct
idle_work
;
enum
row_queue_prio
idling_queue_idx
;
};
/**
* struct starvation_data - data for starvation management
* @starvation_limit: number of times this priority class
* can tolerate being starved
* @starvation_counter: number of requests from higher
* priority classes that were dispatched while this
* priority request were pending
*
*/
struct
starvation_data
{
int
starvation_limit
;
int
starvation_counter
;
};
/**
* struct row_queue - Per block device rqueue structure
* @dispatch_queue: dispatch rqueue
* @row_queues: array of priority request queues
* @rd_idle_data: data for idling after READ request
* @nr_reqs: nr_reqs[0] holds the number of all READ requests in
* scheduler, nr_reqs[1] holds the number of all WRITE
* requests in scheduler
* @urgent_in_flight: flag indicating that there is an urgent
* request that was dispatched to driver and is yet to
* complete.
* @pending_urgent_rq: pointer to the pending urgent request
* @last_served_ioprio_class: I/O priority class that was last dispatched from
* @reg_prio_starvation: starvation data for REGULAR priority queues
* @low_prio_starvation: starvation data for LOW priority queues
* @cycle_flags: used for marking unserved queueus
*
*/
struct
row_data
{
struct
request_queue
*
dispatch_queue
;
struct
row_queue
row_queues
[
ROWQ_MAX_PRIO
];
struct
idling_data
rd_idle_data
;
unsigned
int
nr_reqs
[
2
];
bool
urgent_in_flight
;
struct
request
*
pending_urgent_rq
;
int
last_served_ioprio_class
;
#define
ROW_REG_STARVATION_TOLLERANCE
5000
struct
starvation_data
reg_prio_starvation
;
#define
ROW_LOW_STARVATION_TOLLERANCE
10000
struct
starvation_data
low_prio_starvation
;
unsigned
int
cycle_flags
;
};
#define
RQ_ROWQ
(
rq
) ((struct row_queue *) ((rq)->elv.priv[0]))
#define
row_log
(
q
,
fmt
,
args
...) \
blk_add_trace_msg(q, "%s():" fmt , __func__, ##args)
#define
row_log_rowq
(
rdata
,
rowq_id
,
fmt
,
args
...) \
blk_add_trace_msg(rdata->dispatch_queue, "rowq%d " fmt, \
rowq_id, ##args)
static
inline
void
row_mark_rowq_unserved
(
struct
row_data
*
rd
,
enum
row_queue_prio
qnum
)
{
rd
->
cycle_flags
|= (
1
<<
qnum
);
}
static
inline
void
row_clear_rowq_unserved
(
struct
row_data
*
rd
,
enum
row_queue_prio
qnum
)
{
rd
->
cycle_flags
&= ~(
1
<<
qnum
);
}
static
inline
int
row_rowq_unserved
(
struct
row_data
*
rd
,
enum
row_queue_prio
qnum
)
{
return
rd
->
cycle_flags
&
(
1
<<
qnum
);
}
static
inline
void
__maybe_unused
row_dump_queues_stat
(
struct
row_data
*
rd
)
{
int
i
;
row_log
(
rd
->
dispatch_queue
,
" Queues status:"
);
for
(
i
=
0
;
i
<
ROWQ_MAX_PRIO
;
i
++
)
row_log
(
rd
->
dispatch_queue
,
"queue%d: dispatched= %d, nr_req=%d"
,
i
,
rd
->
row_queues
[
i
].
nr_dispatched
,
rd
->
row_queues
[
i
].
nr_req
);
}
/******************** Static helper functions ***********************/
static
void
kick_queue
(
struct
work_struct
*
work
)
{
struct
idling_data
*
read_data
=
container_of
(
work
,
struct
idling_data
,
idle_work
);
struct
row_data
*
rd
=
container_of
(
read_data
,
struct
row_data
,
rd_idle_data
);
blk_run_queue
(
rd
->
dispatch_queue
);
}
static
enum
hrtimer_restart
row_idle_hrtimer_fn
(
struct
hrtimer
*
hr_timer
)
{
struct
idling_data
*
read_data
=
container_of
(
hr_timer
,
struct
idling_data
,
hr_timer
);
struct
row_data
*
rd
=
container_of
(
read_data
,
struct
row_data
,
rd_idle_data
);
row_log_rowq
(
rd
,
rd
->
rd_idle_data
.
idling_queue_idx
,
"Performing delayed work"
);
/* Mark idling process as done */
rd
->
row_queues
[
rd
->
rd_idle_data
.
idling_queue_idx
].
idle_data
.
begin_idling
=
false;
rd
->
rd_idle_data
.
idling_queue_idx
=
ROWQ_MAX_PRIO
;
if
(!
rd
->
nr_reqs
[
READ
]
&&
!
rd
->
nr_reqs
[
WRITE
])
row_log
(
rd
->
dispatch_queue
,
"No requests in scheduler"
);
else
kblockd_schedule_work
(
rd
->
dispatch_queue
,
&
read_data
->
idle_work
);
return
HRTIMER_NORESTART
;
}
/*
* row_regular_req_pending() - Check if there are REGULAR priority requests
* Pending in scheduler
* @rd: pointer to struct row_data
*
* Returns True if there are REGULAR priority requests in scheduler queues.
* False, otherwise.
*/
static
inline
bool
row_regular_req_pending
(
struct
row_data
*
rd
)
{
int
i
;
for
(
i
=
ROWQ_REG_PRIO_IDX
;
i
<
ROWQ_LOW_PRIO_IDX
;
i
++
)
if
(!
list_empty
(
&
rd
->
row_queues
[
i
].
fifo
))
return
true;
return
false;
}
/*
* row_low_req_pending() - Check if there are LOW priority requests
* Pending in scheduler
* @rd: pointer to struct row_data
*
* Returns True if there are LOW priority requests in scheduler queues.
* False, otherwise.
*/
static
inline
bool
row_low_req_pending
(
struct
row_data
*
rd
)
{
int
i
;
for
(
i
=
ROWQ_LOW_PRIO_IDX
;
i
<
ROWQ_MAX_PRIO
;
i
++
)
if
(!
list_empty
(
&
rd
->
row_queues
[
i
].
fifo
))
return
true;
return
false;
}
/******************* Elevator callback functions *********************/
/*
* row_add_request() - Add request to the scheduler
* @q: requests queue
* @rq: request to add
*
*/
static
void
row_add_request
(
struct
request_queue
*
q
,
struct
request
*
rq
)
{
struct
row_data
*
rd
=
(
struct
row_data
*
)
q
->
elevator
->
elevator_data
;
struct
row_queue
*
rqueue
=
RQ_ROWQ
(
rq
);
s64
diff_ms
;
bool
queue_was_empty
=
list_empty
(
&
rqueue
->
fifo
);
unsigned long
bv_page_flags
=
0
;
if
(
rq
->
bio
&&
rq
->
bio
->
bi_io_vec
&&
rq
->
bio
->
bi_io_vec
->
bv_page
)
bv_page_flags
=
rq
->
bio
->
bi_io_vec
->
bv_page
->
flags
;
list_add_tail
(
&
rq
->
queuelist
,
&
rqueue
->
fifo
);
rd
->
nr_reqs
[
rq_data_dir
(
rq
)]
++
;
rqueue
->
nr_req
++
;
rq_set_fifo_time
(
rq
,
jiffies
);
/* for statistics*/
if
(
rq
->
cmd_flags
&
REQ_URGENT
) {
WARN_ON
(
1
);
blk_dump_rq_flags
(
rq
,
""
);
rq
->
cmd_flags
&= ~
REQ_URGENT
;
}
if
(
row_queues_def
[
rqueue
->
prio
].
idling_enabled
) {
if
(
rd
->
rd_idle_data
.
idling_queue_idx
==
rqueue
->
prio
&&
hrtimer_active
(
&
rd
->
rd_idle_data
.
hr_timer
)) {
if
(
hrtimer_try_to_cancel
(
&
rd
->
rd_idle_data
.
hr_timer
) >=
0
) {
row_log_rowq
(
rd
,
rqueue
->
prio
,
"Canceled delayed work on %d"
,
rd
->
rd_idle_data
.
idling_queue_idx
);
rd
->
rd_idle_data
.
idling_queue_idx
=
ROWQ_MAX_PRIO
;
}
}
diff_ms
=
ktime_to_ms
(
ktime_sub
(
ktime_get
(),
rqueue
->
idle_data
.
last_insert_time
));
if
(
unlikely
(
diff_ms
<
0
)) {
pr_err
(
"%s(): time delta error: diff_ms < 0"
,
__func__
);
rqueue
->
idle_data
.
begin_idling
=
false;
return
;
}
if
((
bv_page_flags
&
(
1L
<<
PG_readahead
))
||
(
diff_ms
<
rd
->
rd_idle_data
.
freq_ms
)) {
rqueue
->
idle_data
.
begin_idling
=
true;
row_log_rowq
(
rd
,
rqueue
->
prio
,
"Enable idling"
);
}
else
{
rqueue
->
idle_data
.
begin_idling
=
false;
row_log_rowq
(
rd
,
rqueue
->
prio
,
"Disable idling (%ldms)"
,
(
long
)
diff_ms
);
}
rqueue
->
idle_data
.
last_insert_time
=
ktime_get
();
}
if
(
row_queues_def
[
rqueue
->
prio
].
is_urgent
&&
!
rd
->
pending_urgent_rq
&&
!
rd
->
urgent_in_flight
) {
/* Handle High Priority queues */
if
(
rqueue
->
prio
<
ROWQ_REG_PRIO_IDX
&&
rd
->
last_served_ioprio_class
!=
IOPRIO_CLASS_RT
&&
queue_was_empty
) {
row_log_rowq
(
rd
,
rqueue
->
prio
,
"added (high prio) urgent request"
);
rq
->
cmd_flags
|=
REQ_URGENT
;
rd
->
pending_urgent_rq
=
rq
;
}
else
if
(
row_rowq_unserved
(
rd
,
rqueue
->
prio
)) {
/* Handle Regular priotity queues */
row_log_rowq
(
rd
,
rqueue
->
prio
,
"added urgent request (total on queue=%d)"
,
rqueue
->
nr_req
);
rq
->
cmd_flags
|=
REQ_URGENT
;
rd
->
pending_urgent_rq
=
rq
;
}
}
else
row_log_rowq
(
rd
,
rqueue
->
prio
,
"added request (total on queue=%d)"
,
rqueue
->
nr_req
);
}
/**
* row_reinsert_req() - Reinsert request back to the scheduler
* @q: requests queue
* @rq: request to add
*
* Reinsert the given request back to the queue it was
* dispatched from as if it was never dispatched.
*
* Returns 0 on success, error code otherwise
*/
static
int
row_reinsert_req
(
struct
request_queue
*
q
,
struct
request
*
rq
)
{
struct
row_data
*
rd
=
q
->
elevator
->
elevator_data
;
struct
row_queue
*
rqueue
=
RQ_ROWQ
(
rq
);
if
(!
rqueue
||
rqueue
->
prio
>=
ROWQ_MAX_PRIO
)
return
-
EIO
;
list_add
(
&
rq
->
queuelist
,
&
rqueue
->
fifo
);
rd
->
nr_reqs
[
rq_data_dir
(
rq
)]
++
;
rqueue
->
nr_req
++
;
row_log_rowq
(
rd
,
rqueue
->
prio
,
"%s request reinserted (total on queue=%d)"
,
(
rq_data_dir
(
rq
)
==
READ
?
"READ"
:
"write"
),
rqueue
->
nr_req
);
if
(
rq
->
cmd_flags
&
REQ_URGENT
) {
/*
* It's not compliant with the design to re-insert
* urgent requests. We want to be able to track this
* down.
*/
WARN_ON
(
1
);
if
(!
rd
->
urgent_in_flight
) {
pr_err
(
"%s(): no urgent in flight"
,
__func__
);
}
else
{
rd
->
urgent_in_flight
=
false;
pr_err
(
"%s(): reinserting URGENT %s req"
,
__func__
,
(
rq_data_dir
(
rq
)
==
READ
?
"READ"
:
"WRITE"
));
if
(
rd
->
pending_urgent_rq
) {
pr_err
(
"%s(): urgent rq is pending"
,
__func__
);
rd
->
pending_urgent_rq
->
cmd_flags
&= ~
REQ_URGENT
;
}
rd
->
pending_urgent_rq
=
rq
;
}
}
return
0
;
}
static
void
row_completed_req
(
struct
request_queue
*
q
,
struct
request
*
rq
)
{
struct
row_data
*
rd
=
q
->
elevator
->
elevator_data
;
if
(
rq
->
cmd_flags
&
REQ_URGENT
) {
if
(!
rd
->
urgent_in_flight
) {
WARN_ON
(
1
);
pr_err
(
"%s(): URGENT req but urgent_in_flight = F"
,
__func__
);
}
rd
->
urgent_in_flight
=
false;
rq
->
cmd_flags
&= ~
REQ_URGENT
;
}
row_log
(
q
,
"completed %s %s req."
,
(
rq
->
cmd_flags
&
REQ_URGENT
?
"URGENT"
:
"regular"
),
(
rq_data_dir
(
rq
)
==
READ
?
"READ"
:
"WRITE"
));
}
/**
* row_urgent_pending() - Return TRUE if there is an urgent
* request on scheduler
* @q: requests queue
*/
static
bool
row_urgent_pending
(
struct
request_queue
*
q
)
{
struct
row_data
*
rd
=
q
->
elevator
->
elevator_data
;
if
(
rd
->
urgent_in_flight
) {
row_log
(
rd
->
dispatch_queue
,
"%d urgent requests in flight"
,
rd
->
urgent_in_flight
);
return
false;
}
if
(
rd
->
pending_urgent_rq
) {
row_log
(
rd
->
dispatch_queue
,
"Urgent request pending"
);
return
true;
}
row_log
(
rd
->
dispatch_queue
,
"no urgent request pending/in flight"
);
return
false;
}
/**
* row_remove_request() - Remove given request from scheduler
* @q: requests queue
* @rq: request to remove
*
*/
static
void
row_remove_request
(
struct
row_data
*
rd
,
struct
request
*
rq
)
{
struct
row_queue
*
rqueue
=
RQ_ROWQ
(
rq
);
list_del_init
(
&
(
rq
)
->
queuelist
);
if
(
rd
->
pending_urgent_rq
==
rq
)
rd
->
pending_urgent_rq
=
NULL
;
else
BUG_ON
(
rq
->
cmd_flags
&
REQ_URGENT
);
rqueue
->
nr_req
--
;
rd
->
nr_reqs
[
rq_data_dir
(
rq
)]
--
;
}
/*
* row_dispatch_insert() - move request to dispatch queue
* @rd: pointer to struct row_data
* @rq: the request to dispatch
*
* This function moves the given request to the dispatch queue
*
*/
static
void
row_dispatch_insert
(
struct
row_data
*
rd
,
struct
request
*
rq
)
{
struct
row_queue
*
rqueue
=
RQ_ROWQ
(
rq
);
row_remove_request
(
rd
,
rq
);
elv_dispatch_sort
(
rd
->
dispatch_queue
,
rq
);
if
(
rq
->
cmd_flags
&
REQ_URGENT
) {
WARN_ON
(
rd
->
urgent_in_flight
);
rd
->
urgent_in_flight
=
true;
}
rqueue
->
nr_dispatched
++
;
row_clear_rowq_unserved
(
rd
,
rqueue
->
prio
);
row_log_rowq
(
rd
,
rqueue
->
prio
,
" Dispatched request %p nr_disp = %d"
,
rq
,
rqueue
->
nr_dispatched
);
if
(
rqueue
->
prio
<
ROWQ_REG_PRIO_IDX
) {
rd
->
last_served_ioprio_class
=
IOPRIO_CLASS_RT
;
if
(
row_regular_req_pending
(
rd
))
rd
->
reg_prio_starvation
.
starvation_counter
++
;
if
(
row_low_req_pending
(
rd
))
rd
->
low_prio_starvation
.
starvation_counter
++
;
}
else
if
(
rqueue
->
prio
<
ROWQ_LOW_PRIO_IDX
) {
rd
->
last_served_ioprio_class
=
IOPRIO_CLASS_BE
;
rd
->
reg_prio_starvation
.
starvation_counter
=
0
;
if
(
row_low_req_pending
(
rd
))
rd
->
low_prio_starvation
.
starvation_counter
++
;
}
else
{
rd
->
last_served_ioprio_class
=
IOPRIO_CLASS_IDLE
;
rd
->
low_prio_starvation
.
starvation_counter
=
0
;
}
}
/*
* row_get_ioprio_class_to_serve() - Return the next I/O priority
* class to dispatch requests from
* @rd: pointer to struct row_data
* @force: flag indicating if forced dispatch
*
* This function returns the next I/O priority class to serve
* {IOPRIO_CLASS_NONE, IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE}.
* If there are no more requests in scheduler or if we're idling on some queue
* IOPRIO_CLASS_NONE will be returned.
* If idling is scheduled on a lower priority queue than the one that needs
* to be served, it will be canceled.
*
*/
static
int
row_get_ioprio_class_to_serve
(
struct
row_data
*
rd
,
int
force
)
{
int
i
;
int
ret
=
IOPRIO_CLASS_NONE
;
if
(!
rd
->
nr_reqs
[
READ
]
&&
!
rd
->
nr_reqs
[
WRITE
]) {
row_log
(
rd
->
dispatch_queue
,
"No more requests in scheduler"
);
goto
check_idling
;
}
/* First, go over the high priority queues */
for
(
i
=
0
;
i
<
ROWQ_REG_PRIO_IDX
;
i
++
) {
if
(!
list_empty
(
&
rd
->
row_queues
[
i
].
fifo
)) {
if
(
hrtimer_active
(
&
rd
->
rd_idle_data
.
hr_timer
)) {
if
(
hrtimer_try_to_cancel
(
&
rd
->
rd_idle_data
.
hr_timer
) >=
0
) {
row_log
(
rd
->
dispatch_queue
,
"Canceling delayed work on %d. RT pending"
,
rd
->
rd_idle_data
.
idling_queue_idx
);
rd
->
rd_idle_data
.
idling_queue_idx
=
ROWQ_MAX_PRIO
;
}
}
if
(
row_regular_req_pending
(
rd
)
&&
(
rd
->
reg_prio_starvation
.
starvation_counter
>=
rd
->
reg_prio_starvation
.
starvation_limit
))
ret
=
IOPRIO_CLASS_BE
;
else
if
(
row_low_req_pending
(
rd
)
&&
(
rd
->
low_prio_starvation
.
starvation_counter
>=
rd
->
low_prio_starvation
.
starvation_limit
))
ret
=
IOPRIO_CLASS_IDLE
;
else
ret
=
IOPRIO_CLASS_RT
;
goto
done
;
}
}
/*
* At the moment idling is implemented only for READ queues.
* If enabled on WRITE, this needs updating
*/
if
(
hrtimer_active
(
&
rd
->
rd_idle_data
.
hr_timer
)) {
row_log
(
rd
->
dispatch_queue
,
"Delayed work pending. Exiting"
);
goto
done
;
}
check_idling
:
/* Check for (high priority) idling and enable if needed */
for
(
i
=
0
;
i
<
ROWQ_REG_PRIO_IDX
&&
!
force
;
i
++
) {
if
(
rd
->
row_queues
[
i
].
idle_data
.
begin_idling
&&
row_queues_def
[
i
].
idling_enabled
)
goto
initiate_idling
;
}
/* Regular priority queues */
for
(
i
=
ROWQ_REG_PRIO_IDX
;
i
<
ROWQ_LOW_PRIO_IDX
;
i
++
) {
if
(
list_empty
(
&
rd
->
row_queues
[
i
].
fifo
)) {
/* We can idle only if this is not a forced dispatch */
if
(
rd
->
row_queues
[
i
].
idle_data
.
begin_idling
&&
!
force
&&
row_queues_def
[
i
].
idling_enabled
)
goto
initiate_idling
;
}
else
{
if
(
row_low_req_pending
(
rd
)
&&
(
rd
->
low_prio_starvation
.
starvation_counter
>=
rd
->
low_prio_starvation
.
starvation_limit
))
ret
=
IOPRIO_CLASS_IDLE
;
else
ret
=
IOPRIO_CLASS_BE
;
goto
done
;
}
}
if
(
rd
->
nr_reqs
[
READ
]
||
rd
->
nr_reqs
[
WRITE
])
ret
=
IOPRIO_CLASS_IDLE
;
goto
done
;
initiate_idling
:
hrtimer_start
(
&
rd
->
rd_idle_data
.
hr_timer
,
ktime_set
(
0
,
rd
->
rd_idle_data
.
idle_time_ms
*
NSEC_PER_MSEC
),
HRTIMER_MODE_REL
);
rd
->
rd_idle_data
.
idling_queue_idx
=
i
;
row_log_rowq
(
rd
,
i
,
"Scheduled delayed work on %d. exiting"
,
i
);
done
:
return
ret
;
}
static
void
row_restart_cycle
(
struct
row_data
*
rd
,
int
start_idx
,
int
end_idx
)
{
int
i
;
row_dump_queues_stat
(
rd
);
for
(
i
=
start_idx
;
i
<
end_idx
;
i
++
) {
if
(
rd
->
row_queues
[
i
].
nr_dispatched
<
rd
->
row_queues
[
i
].
disp_quantum
)
row_mark_rowq_unserved
(
rd
,
i
);
rd
->
row_queues
[
i
].
nr_dispatched
=
0
;
}
row_log
(
rd
->
dispatch_queue
,
"Restarting cycle for class @ %d-%d"
,
start_idx
,
end_idx
);
}
/*
* row_get_next_queue() - selects the next queue to dispatch from
* @q: requests queue
* @rd: pointer to struct row_data
* @start_idx/end_idx: indexes in the row_queues array to select a queue
* from.
*
* Return index of the queues to dispatch from. Error code if fails.
*
*/
static
int
row_get_next_queue
(
struct
request_queue
*
q
,
struct
row_data
*
rd
,
int
start_idx
,
int
end_idx
)
{
int
i
=
start_idx
;
bool
restart
=
true;
int
ret
=
-
EIO
;
do
{
if
(
list_empty
(
&
rd
->
row_queues
[
i
].
fifo
)
||
rd
->
row_queues
[
i
].
nr_dispatched
>=
rd
->
row_queues
[
i
].
disp_quantum
) {
i
++
;
if
(
i
==
end_idx
&&
restart
) {
/* Restart cycle for this priority class */
row_restart_cycle
(
rd
,
start_idx
,
end_idx
);
i
=
start_idx
;
restart
=
false;
}
}
else
{
ret
=
i
;
break
;
}
}
while
(
i
<
end_idx
);
return
ret
;
}
/*
* row_dispatch_requests() - selects the next request to dispatch
* @q: requests queue
* @force: flag indicating if forced dispatch
*
* Return 0 if no requests were moved to the dispatch queue.
* 1 otherwise
*
*/
static
int
row_dispatch_requests
(
struct
request_queue
*
q
,
int
force
)
{
struct
row_data
*
rd
=
(
struct
row_data
*
)
q
->
elevator
->
elevator_data
;
int
ret
=
0
,
currq
,
ioprio_class_to_serve
,
start_idx
,
end_idx
;
if
(
force
&&
hrtimer_active
(
&
rd
->
rd_idle_data
.
hr_timer
)) {
if
(
hrtimer_try_to_cancel
(
&
rd
->
rd_idle_data
.
hr_timer
) >=
0
) {
row_log
(
rd
->
dispatch_queue
,
"Canceled delayed work on %d - forced dispatch"
,
rd
->
rd_idle_data
.
idling_queue_idx
);
rd
->
rd_idle_data
.
idling_queue_idx
=
ROWQ_MAX_PRIO
;
}
}
if
(
rd
->
pending_urgent_rq
) {
row_log
(
rd
->
dispatch_queue
,
"dispatching urgent request"
);
row_dispatch_insert
(
rd
,
rd
->
pending_urgent_rq
);
ret
=
1
;
goto
done
;
}
ioprio_class_to_serve
=
row_get_ioprio_class_to_serve
(
rd
,
force
);
row_log
(
rd
->
dispatch_queue
,
"Dispatching from %d priority class"
,
ioprio_class_to_serve
);
switch
(
ioprio_class_to_serve
) {
case
IOPRIO_CLASS_NONE
:
rd
->
last_served_ioprio_class
=
IOPRIO_CLASS_NONE
;
goto
done
;
case
IOPRIO_CLASS_RT
:
start_idx
=
ROWQ_HIGH_PRIO_IDX
;
end_idx
=
ROWQ_REG_PRIO_IDX
;
break
;
case
IOPRIO_CLASS_BE
:
start_idx
=
ROWQ_REG_PRIO_IDX
;
end_idx
=
ROWQ_LOW_PRIO_IDX
;
break
;
case
IOPRIO_CLASS_IDLE
:
start_idx
=
ROWQ_LOW_PRIO_IDX
;
end_idx
=
ROWQ_MAX_PRIO
;
break
;
default
:
pr_err
(
"%s(): Invalid I/O priority class"
,
__func__
);
goto
done
;
}
currq
=
row_get_next_queue
(
q
,
rd
,
start_idx
,
end_idx
);
/* Dispatch */
if
(
currq
>=
0
) {
row_dispatch_insert
(
rd
,
rq_entry_fifo
(
rd
->
row_queues
[
currq
].
fifo
.
next
));
ret
=
1
;
}
done
:
return
ret
;
}
/*
* row_init_queue() - Init scheduler data structures
* @q: requests queue
*
* Return pointer to struct row_data to be saved in elevator for
* this dispatch queue
*
*/
static
void
*
row_init_queue
(
struct
request_queue
*
q
)
{
struct
row_data
*
rdata
;
int
i
;
rdata
=
kmalloc_node
(
sizeof
(
*
rdata
),
GFP_KERNEL
|
__GFP_ZERO
,
q
->
node
);
if
(!
rdata
)
return
NULL
;
memset
(
rdata
,
0
,
sizeof
(
*
rdata
));
for
(
i
=
0
;
i
<
ROWQ_MAX_PRIO
;
i
++
) {
INIT_LIST_HEAD
(
&
rdata
->
row_queues
[
i
].
fifo
);
rdata
->
row_queues
[
i
].
disp_quantum
=
row_queues_def
[
i
].
quantum
;
rdata
->
row_queues
[
i
].
rdata
=
rdata
;
rdata
->
row_queues
[
i
].
prio
=
i
;
rdata
->
row_queues
[
i
].
idle_data
.
begin_idling
=
false;
rdata
->
row_queues
[
i
].
idle_data
.
last_insert_time
=
ktime_set
(
0
,
0
);
}
rdata
->
reg_prio_starvation
.
starvation_limit
=
ROW_REG_STARVATION_TOLLERANCE
;
rdata
->
low_prio_starvation
.
starvation_limit
=
ROW_LOW_STARVATION_TOLLERANCE
;
/*
* Currently idling is enabled only for READ queues. If we want to
* enable it for write queues also, note that idling frequency will
* be the same in both cases
*/
rdata
->
rd_idle_data
.
idle_time_ms
=
ROW_IDLE_TIME_MSEC
;
rdata
->
rd_idle_data
.
freq_ms
=
ROW_READ_FREQ_MSEC
;
hrtimer_init
(
&
rdata
->
rd_idle_data
.
hr_timer
,
CLOCK_MONOTONIC
,
HRTIMER_MODE_REL
);
rdata
->
rd_idle_data
.
hr_timer
.
function
=
&
row_idle_hrtimer_fn
;
INIT_WORK
(
&
rdata
->
rd_idle_data
.
idle_work
,
kick_queue
);
rdata
->
last_served_ioprio_class
=
IOPRIO_CLASS_NONE
;
rdata
->
rd_idle_data
.
idling_queue_idx
=
ROWQ_MAX_PRIO
;
rdata
->
dispatch_queue
=
q
;
return
rdata
;
}
/*
* row_exit_queue() - called on unloading the RAW scheduler
* @e: poiner to struct elevator_queue
*
*/
static
void
row_exit_queue
(
struct
elevator_queue
*
e
)
{
struct
row_data
*
rd
=
(
struct
row_data
*
)
e
->
elevator_data
;
int
i
;
for
(
i
=
0
;
i
<
ROWQ_MAX_PRIO
;
i
++
)
BUG_ON
(!
list_empty
(
&
rd
->
row_queues
[
i
].
fifo
));
if
(
hrtimer_cancel
(
&
rd
->
rd_idle_data
.
hr_timer
))
pr_err
(
"%s(): idle timer was active!"
,
__func__
);
rd
->
rd_idle_data
.
idling_queue_idx
=
ROWQ_MAX_PRIO
;
kfree
(
rd
);
}
/*
* row_merged_requests() - Called when 2 requests are merged
* @q: requests queue
* @rq: request the two requests were merged into
* @next: request that was merged
*/
static
void
row_merged_requests
(
struct
request_queue
*
q
,
struct
request
*
rq
,
struct
request
*
next
)
{
struct
row_queue
*
rqueue
=
RQ_ROWQ
(
next
);
list_del_init
(
&
next
->
queuelist
);
rqueue
->
nr_req
--
;
if
(
rqueue
->
rdata
->
pending_urgent_rq
==
next
) {
pr_err
(
"\n\nROW_WARNING: merging pending urgent!"
);
rqueue
->
rdata
->
pending_urgent_rq
=
rq
;
rq
->
cmd_flags
|=
REQ_URGENT
;
WARN_ON
(!(
next
->
cmd_flags
&
REQ_URGENT
));
next
->
cmd_flags
&= ~
REQ_URGENT
;
}
rqueue
->
rdata
->
nr_reqs
[
rq_data_dir
(
rq
)]
--
;
}
/*
* row_get_queue_prio() - Get queue priority for a given request
*
* This is a helping function which purpose is to determine what
* ROW queue the given request should be added to (and
* dispatched from later on)
*
*/
static
enum
row_queue_prio
row_get_queue_prio
(
struct
request
*
rq
,
struct
row_data
*
rd
)
{
const
int
data_dir
=
rq_data_dir
(
rq
);
const
bool
is_sync
=
rq_is_sync
(
rq
);
enum
row_queue_prio
q_type
=
ROWQ_MAX_PRIO
;
int
ioprio_class
=
IOPRIO_PRIO_CLASS
(
rq
->
elv
.
icq
->
ioc
->
ioprio
);
switch
(
ioprio_class
) {
case
IOPRIO_CLASS_RT
:
if
(
data_dir
==
READ
)
q_type
=
ROWQ_PRIO_HIGH_READ
;
else
if
(
is_sync
)
q_type
=
ROWQ_PRIO_HIGH_SWRITE
;
else
{
pr_err
(
"%s:%s(): got a simple write from RT_CLASS. How???"
,
rq
->
rq_disk
->
disk_name
,
__func__
);
q_type
=
ROWQ_PRIO_REG_WRITE
;
}
break
;
case
IOPRIO_CLASS_IDLE
:
if
(
data_dir
==
READ
)
q_type
=
ROWQ_PRIO_LOW_READ
;
else
if
(
is_sync
)
q_type
=
ROWQ_PRIO_LOW_SWRITE
;
else
{
pr_err
(
"%s:%s(): got a simple write from IDLE_CLASS. How???"
,
rq
->
rq_disk
->
disk_name
,
__func__
);
q_type
=
ROWQ_PRIO_REG_WRITE
;
}
break
;
case
IOPRIO_CLASS_NONE
:
case
IOPRIO_CLASS_BE
:
default
:
if
(
data_dir
==
READ
)
q_type
=
ROWQ_PRIO_REG_READ
;
else
if
(
is_sync
)
q_type
=
ROWQ_PRIO_REG_SWRITE
;
else
q_type
=
ROWQ_PRIO_REG_WRITE
;
break
;
}
return
q_type
;
}
/*
* row_set_request() - Set ROW data structures associated with this request.
* @q: requests queue
* @rq: pointer to the request
* @gfp_mask: ignored
*
*/
static
int
row_set_request
(
struct
request_queue
*
q
,
struct
request
*
rq
,
gfp_t
gfp_mask
)
{
struct
row_data
*
rd
=
(
struct
row_data
*
)
q
->
elevator
->
elevator_data
;
unsigned long
flags
;
spin_lock_irqsave
(
q
->
queue_lock
,
flags
);
rq
->
elv
.
priv
[
0
]
=
(
void
*
)(
&
rd
->
row_queues
[
row_get_queue_prio
(
rq
,
rd
)]);
spin_unlock_irqrestore
(
q
->
queue_lock
,
flags
);
return
0
;
}
/********** Helping sysfs functions/defenitions for ROW attributes ******/
static
ssize_t
row_var_show
(
int
var
,
char
*
page
)
{
return
snprintf
(
page
,
100
,
"%d\n"
,
var
);
}
static
ssize_t
row_var_store
(
int
*
var
,
const
char
*
page
,
size_t
count
)
{
int
err
;
err
=
kstrtoul
(
page
,
10
, (
unsigned long
*
)
var
);
return
count
;
}
#define
SHOW_FUNCTION
(
__FUNC
,
__VAR
) \
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
{ \
struct row_data *rowd = e->elevator_data; \
int __data = __VAR; \
return row_var_show(__data, (page)); \
}
SHOW_FUNCTION
(
row_hp_read_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_HIGH_READ
].
disp_quantum
);
SHOW_FUNCTION
(
row_rp_read_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_REG_READ
].
disp_quantum
);
SHOW_FUNCTION
(
row_hp_swrite_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_HIGH_SWRITE
].
disp_quantum
);
SHOW_FUNCTION
(
row_rp_swrite_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_REG_SWRITE
].
disp_quantum
);
SHOW_FUNCTION
(
row_rp_write_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_REG_WRITE
].
disp_quantum
);
SHOW_FUNCTION
(
row_lp_read_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_LOW_READ
].
disp_quantum
);
SHOW_FUNCTION
(
row_lp_swrite_quantum_show
,
rowd
->
row_queues
[
ROWQ_PRIO_LOW_SWRITE
].
disp_quantum
);
SHOW_FUNCTION
(
row_rd_idle_data_show
,
rowd
->
rd_idle_data
.
idle_time_ms
);
SHOW_FUNCTION
(
row_rd_idle_data_freq_show
,
rowd
->
rd_idle_data
.
freq_ms
);
SHOW_FUNCTION
(
row_reg_starv_limit_show
,
rowd
->
reg_prio_starvation
.
starvation_limit
);
SHOW_FUNCTION
(
row_low_starv_limit_show
,
rowd
->
low_prio_starvation
.
starvation_limit
);
#undef
SHOW_FUNCTION
#define
STORE_FUNCTION
(
__FUNC
,
__PTR
,
MIN
,
MAX
) \
static ssize_t __FUNC(struct elevator_queue *e, \
const char *page, size_t count) \
{ \
struct row_data *rowd = e->elevator_data; \
int __data; \
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