1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
if BLOCK
menu "IO Schedulers"
config IOSCHED_NOOP
bool
default y
---help---
The no-op I/O scheduler is a minimal scheduler that does basic merging
and sorting. Its main uses include non-disk based block devices like
memory devices, and specialised software or hardware environments
that do their own scheduling and require only minimal assistance from
the kernel.
config IOSCHED_DEADLINE
tristate "Deadline I/O scheduler"
default y
---help---
The deadline I/O scheduler is simple and compact. It will provide
CSCAN service with FIFO expiration of requests, switching to
a new point in the service tree and doing a batch of IO from there
in case of expiry.
config IOSCHED_ROW
tristate "ROW I/O scheduler"
default y
---help---
The ROW I/O scheduler gives priority to READ requests over the
WRITE requests when dispatching, without starving WRITE requests.
Requests are kept in priority queues. Dispatching is done in a RR
manner when the dispatch quantum for each queue is calculated
according to queue priority.
Most suitable for mobile devices.
config IOSCHED_SIO
tristate "Simple I/O scheduler"
default y
---help---
The Simple I/O scheduler is an extremely simple scheduler,
based on noop and deadline, that relies on deadlines to
ensure fairness. The algorithm does not do any sorting but
basic merging, trying to keep a minimum overhead. It is aimed
mainly for aleatory access devices (eg: flash devices).
config IOSCHED_ZEN
tristate "Zen I/O scheduler"
default y
---help---
FCFS, dispatches are back-inserted, deadlines ensure fairness.
Should work best with devices where there is no travel delay.
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
default y
---help---
The CFQ I/O scheduler tries to distribute bandwidth equally
among all processes in the system. It should provide a fair
and low latency working environment, suitable for both desktop
and server systems.
This is the default I/O scheduler.
config CFQ_GROUP_IOSCHED
bool "CFQ Group Scheduling support"
depends on IOSCHED_CFQ && BLK_CGROUP
default n
---help---
Enable group IO scheduling in CFQ.
config IOSCHED_SIOPLUS
tristate "Simple I/O scheduler plus"
default y
---help---
The Simple I/O scheduler is an extremely simple scheduler,
based on noop and deadline, that relies on deadlines to
ensure fairness. The algorithm does not do any sorting but
basic merging, trying to keep a minimum overhead. It is aimed
mainly for aleatory access devices (eg: flash devices).
config IOSCHED_FIOPS
tristate "IOPS based I/O scheduler"
default y
---help---
This is an IOPS based I/O scheduler. It will try to distribute
IOPS equally among all processes in the system. It's mainly for
Flash based storage.
config IOSCHED_BFQ
tristate "BFQ I/O scheduler"
default n
---help---
The BFQ I/O scheduler tries to distribute bandwidth among
all processes according to their weights.
It aims at distributing the bandwidth as desired, independently of
the disk parameters and with any workload. It also tries to
guarantee low latency to interactive and soft real-time
applications. If compiled built-in (saying Y here), BFQ can
be configured to support hierarchical scheduling.
config CGROUP_BFQIO
bool "BFQ hierarchical scheduling support"
depends on CGROUPS && IOSCHED_BFQ=y
default n
---help---
Enable hierarchical scheduling in BFQ, using the cgroups
filesystem interface. The name of the subsystem will be
bfqio.
choice
prompt "Default I/O scheduler"
default DEFAULT_CFQ
help
Select the I/O scheduler which will be used by default for all
block devices.
config DEFAULT_DEADLINE
bool "Deadline" if IOSCHED_DEADLINE=y
config DEFAULT_ROW
bool "ROW" if IOSCHED_ROW=y
help
The ROW I/O scheduler gives priority to READ requests
over the WRITE requests when dispatching, without starving
WRITE requests. Requests are kept in priority queues.
Dispatching is done in a RR manner when the dispatch quantum
for each queue is defined according to queue priority.
Most suitable for mobile devices.
config DEFAULT_SIO
bool "SIO" if IOSCHED_SIO=y
config DEFAULT_CFQ
bool "CFQ" if IOSCHED_CFQ=y
config DEFAULT_SIOPLUS
bool "SIOPLUS" if IOSCHED_SIOPLUS=y
config DEFAULT_ZEN
bool "ZEN" if IOSCHED_ZEN=y
config DEFAULT_FIOPS
bool "FIOPS" if IOSCHED_FIOPS=y
config DEFAULT_BFQ
bool "BFQ" if IOSCHED_BFQ=y
help
Selects BFQ as the default I/O scheduler which will be
used by default for all block devices.
The BFQ I/O scheduler aims at distributing the bandwidth
as desired, independently of the disk parameters and with
any workload. It also tries to guarantee low latency to
interactive and soft real-time applications.
config DEFAULT_NOOP
bool "No-op"
endchoice
config DEFAULT_IOSCHED
string
default "deadline" if DEFAULT_DEADLINE
default "row" if DEFAULT_ROW
default "sio" if DEFAULT_SIO
default "cfq" if DEFAULT_CFQ
default "fiops" if DEFAULT_FIOPS
default "bfq" if DEFAULT_BFQ
default "noop" if DEFAULT_NOOP
default "zen" if DEFAULT_ZEN
default "sioplus" if DEFAULT_SIOPLUS
endmenu
endif
|
