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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-08 11:19:16 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-08 11:19:16 -0500
commit6035ccd8e9e40bb654fbfdef325902ab531679a5 (patch)
treec1810d8a4d4ef150cdf14af72e6087dfc3f4b6e0 /Documentation
parent23eb3b64b5e44680c867e165fe1cd18e57fba255 (diff)
parent878eaddd05d251cefa9632c2b8046833c5eead66 (diff)
Merge branch 'for-2.6.33' of git://git.kernel.dk/linux-2.6-block
* 'for-2.6.33' of git://git.kernel.dk/linux-2.6-block: (113 commits) cfq-iosched: Do not access cfqq after freeing it block: include linux/err.h to use ERR_PTR cfq-iosched: use call_rcu() instead of doing grace period stall on queue exit blkio: Allow CFQ group IO scheduling even when CFQ is a module blkio: Implement dynamic io controlling policy registration blkio: Export some symbols from blkio as its user CFQ can be a module block: Fix io_context leak after failure of clone with CLONE_IO block: Fix io_context leak after clone with CLONE_IO cfq-iosched: make nonrot check logic consistent io controller: quick fix for blk-cgroup and modular CFQ cfq-iosched: move IO controller declerations to a header file cfq-iosched: fix compile problem with !CONFIG_CGROUP blkio: Documentation blkio: Wait on sync-noidle queue even if rq_noidle = 1 blkio: Implement group_isolation tunable blkio: Determine async workload length based on total number of queues blkio: Wait for cfq queue to get backlogged if group is empty blkio: Propagate cgroup weight updation to cfq groups blkio: Drop the reference to queue once the task changes cgroup blkio: Provide some isolation between groups ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/blockdev/drbd/DRBD-8.3-data-packets.svg588
-rw-r--r--Documentation/blockdev/drbd/DRBD-data-packets.svg459
-rw-r--r--Documentation/blockdev/drbd/README.txt16
-rw-r--r--Documentation/blockdev/drbd/conn-states-8.dot18
-rw-r--r--Documentation/blockdev/drbd/disk-states-8.dot16
-rw-r--r--Documentation/blockdev/drbd/drbd-connection-state-overview.dot85
-rw-r--r--Documentation/blockdev/drbd/node-states-8.dot14
-rw-r--r--Documentation/cgroups/blkio-controller.txt135
8 files changed, 1331 insertions, 0 deletions
diff --git a/Documentation/blockdev/drbd/DRBD-8.3-data-packets.svg b/Documentation/blockdev/drbd/DRBD-8.3-data-packets.svg
new file mode 100644
index 000000000000..f87cfa0dc2fb
--- /dev/null
+++ b/Documentation/blockdev/drbd/DRBD-8.3-data-packets.svg
@@ -0,0 +1,588 @@
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diff --git a/Documentation/blockdev/drbd/DRBD-data-packets.svg b/Documentation/blockdev/drbd/DRBD-data-packets.svg
new file mode 100644
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diff --git a/Documentation/blockdev/drbd/README.txt b/Documentation/blockdev/drbd/README.txt
new file mode 100644
index 000000000000..627b0a1bf35e
--- /dev/null
+++ b/Documentation/blockdev/drbd/README.txt
@@ -0,0 +1,16 @@
1Description
2
3 DRBD is a shared-nothing, synchronously replicated block device. It
4 is designed to serve as a building block for high availability
5 clusters and in this context, is a "drop-in" replacement for shared
6 storage. Simplistically, you could see it as a network RAID 1.
7
8 Please visit http://www.drbd.org to find out more.
9
10The here included files are intended to help understand the implementation
11
12DRBD-8.3-data-packets.svg, DRBD-data-packets.svg
13 relates some functions, and write packets.
14
15conn-states-8.dot, disk-states-8.dot, node-states-8.dot
16 The sub graphs of DRBD's state transitions
diff --git a/Documentation/blockdev/drbd/conn-states-8.dot b/Documentation/blockdev/drbd/conn-states-8.dot
new file mode 100644
index 000000000000..025e8cf5e64a
--- /dev/null
+++ b/Documentation/blockdev/drbd/conn-states-8.dot
@@ -0,0 +1,18 @@
1digraph conn_states {
2 StandAllone -> WFConnection [ label = "ioctl_set_net()" ]
3 WFConnection -> Unconnected [ label = "unable to bind()" ]
4 WFConnection -> WFReportParams [ label = "in connect() after accept" ]
5 WFReportParams -> StandAllone [ label = "checks in receive_param()" ]
6 WFReportParams -> Connected [ label = "in receive_param()" ]
7 WFReportParams -> WFBitMapS [ label = "sync_handshake()" ]
8 WFReportParams -> WFBitMapT [ label = "sync_handshake()" ]
9 WFBitMapS -> SyncSource [ label = "receive_bitmap()" ]
10 WFBitMapT -> SyncTarget [ label = "receive_bitmap()" ]
11 SyncSource -> Connected
12 SyncTarget -> Connected
13 SyncSource -> PausedSyncS
14 SyncTarget -> PausedSyncT
15 PausedSyncS -> SyncSource
16 PausedSyncT -> SyncTarget
17 Connected -> WFConnection [ label = "* on network error" ]
18}
diff --git a/Documentation/blockdev/drbd/disk-states-8.dot b/Documentation/blockdev/drbd/disk-states-8.dot
new file mode 100644
index 000000000000..d06cfb46fb98
--- /dev/null
+++ b/Documentation/blockdev/drbd/disk-states-8.dot
@@ -0,0 +1,16 @@
1digraph disk_states {
2 Diskless -> Inconsistent [ label = "ioctl_set_disk()" ]
3 Diskless -> Consistent [ label = "ioctl_set_disk()" ]
4 Diskless -> Outdated [ label = "ioctl_set_disk()" ]
5 Consistent -> Outdated [ label = "receive_param()" ]
6 Consistent -> UpToDate [ label = "receive_param()" ]
7 Consistent -> Inconsistent [ label = "start resync" ]
8 Outdated -> Inconsistent [ label = "start resync" ]
9 UpToDate -> Inconsistent [ label = "ioctl_replicate" ]
10 Inconsistent -> UpToDate [ label = "resync completed" ]
11 Consistent -> Failed [ label = "io completion error" ]
12 Outdated -> Failed [ label = "io completion error" ]
13 UpToDate -> Failed [ label = "io completion error" ]
14 Inconsistent -> Failed [ label = "io completion error" ]
15 Failed -> Diskless [ label = "sending notify to peer" ]
16}
diff --git a/Documentation/blockdev/drbd/drbd-connection-state-overview.dot b/Documentation/blockdev/drbd/drbd-connection-state-overview.dot
new file mode 100644
index 000000000000..6d9cf0a7b11d
--- /dev/null
+++ b/Documentation/blockdev/drbd/drbd-connection-state-overview.dot
@@ -0,0 +1,85 @@
1// vim: set sw=2 sts=2 :
2digraph {
3 rankdir=BT
4 bgcolor=white
5
6 node [shape=plaintext]
7 node [fontcolor=black]
8
9 StandAlone [ style=filled,fillcolor=gray,label=StandAlone ]
10
11 node [fontcolor=lightgray]
12
13 Unconnected [ label=Unconnected ]
14
15 CommTrouble [ shape=record,
16 label="{communication loss|{Timeout|BrokenPipe|NetworkFailure}}" ]
17
18 node [fontcolor=gray]
19
20 subgraph cluster_try_connect {
21 label="try to connect, handshake"
22 rank=max
23 WFConnection [ label=WFConnection ]
24 WFReportParams [ label=WFReportParams ]
25 }
26
27 TearDown [ label=TearDown ]
28
29 Connected [ label=Connected,style=filled,fillcolor=green,fontcolor=black ]
30
31 node [fontcolor=lightblue]
32
33 StartingSyncS [ label=StartingSyncS ]
34 StartingSyncT [ label=StartingSyncT ]
35
36 subgraph cluster_bitmap_exchange {
37 node [fontcolor=red]
38 fontcolor=red
39 label="new application (WRITE?) requests blocked\lwhile bitmap is exchanged"
40
41 WFBitMapT [ label=WFBitMapT ]
42 WFSyncUUID [ label=WFSyncUUID ]
43 WFBitMapS [ label=WFBitMapS ]
44 }
45
46 node [fontcolor=blue]
47
48 cluster_resync [ shape=record,label="{<any>resynchronisation process running\l'concurrent' application requests allowed|{{<T>PausedSyncT\nSyncTarget}|{<S>PausedSyncS\nSyncSource}}}" ]
49
50 node [shape=box,fontcolor=black]
51
52 // drbdadm [label="drbdadm connect"]
53 // handshake [label="drbd_connect()\ndrbd_do_handshake\ndrbd_sync_handshake() etc."]
54 // comm_error [label="communication trouble"]
55
56 //
57 // edges
58 // --------------------------------------
59
60 StandAlone -> Unconnected [ label="drbdadm connect" ]
61 Unconnected -> StandAlone [ label="drbdadm disconnect\lor serious communication trouble" ]
62 Unconnected -> WFConnection [ label="receiver thread is started" ]
63 WFConnection -> WFReportParams [ headlabel="accept()\land/or \lconnect()\l" ]
64
65 WFReportParams -> StandAlone [ label="during handshake\lpeers do not agree\labout something essential" ]
66 WFReportParams -> Connected [ label="data identical\lno sync needed",color=green,fontcolor=green ]
67
68 WFReportParams -> WFBitMapS
69 WFReportParams -> WFBitMapT
70 WFBitMapT -> WFSyncUUID [minlen=0.1,constraint=false]
71
72 WFBitMapS -> cluster_resync:S
73 WFSyncUUID -> cluster_resync:T
74
75 edge [color=green]
76 cluster_resync:any -> Connected [ label="resnyc done",fontcolor=green ]
77
78 edge [color=red]
79 WFReportParams -> CommTrouble
80 Connected -> CommTrouble
81 cluster_resync:any -> CommTrouble
82 edge [color=black]
83 CommTrouble -> Unconnected [label="receiver thread is stopped" ]
84
85}
diff --git a/Documentation/blockdev/drbd/node-states-8.dot b/Documentation/blockdev/drbd/node-states-8.dot
new file mode 100644
index 000000000000..4a2b00c23547
--- /dev/null
+++ b/Documentation/blockdev/drbd/node-states-8.dot
@@ -0,0 +1,14 @@
1digraph node_states {
2 Secondary -> Primary [ label = "ioctl_set_state()" ]
3 Primary -> Secondary [ label = "ioctl_set_state()" ]
4}
5
6digraph peer_states {
7 Secondary -> Primary [ label = "recv state packet" ]
8 Primary -> Secondary [ label = "recv state packet" ]
9 Primary -> Unknown [ label = "connection lost" ]
10 Secondary -> Unknown [ label = "connection lost" ]
11 Unknown -> Primary [ label = "connected" ]
12 Unknown -> Secondary [ label = "connected" ]
13}
14
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
new file mode 100644
index 000000000000..630879cd9a42
--- /dev/null
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -0,0 +1,135 @@
1 Block IO Controller
2 ===================
3Overview
4========
5cgroup subsys "blkio" implements the block io controller. There seems to be
6a need of various kinds of IO control policies (like proportional BW, max BW)
7both at leaf nodes as well as at intermediate nodes in a storage hierarchy.
8Plan is to use the same cgroup based management interface for blkio controller
9and based on user options switch IO policies in the background.
10
11In the first phase, this patchset implements proportional weight time based
12division of disk policy. It is implemented in CFQ. Hence this policy takes
13effect only on leaf nodes when CFQ is being used.
14
15HOWTO
16=====
17You can do a very simple testing of running two dd threads in two different
18cgroups. Here is what you can do.
19
20- Enable group scheduling in CFQ
21 CONFIG_CFQ_GROUP_IOSCHED=y
22
23- Compile and boot into kernel and mount IO controller (blkio).
24
25 mount -t cgroup -o blkio none /cgroup
26
27- Create two cgroups
28 mkdir -p /cgroup/test1/ /cgroup/test2
29
30- Set weights of group test1 and test2
31 echo 1000 > /cgroup/test1/blkio.weight
32 echo 500 > /cgroup/test2/blkio.weight
33
34- Create two same size files (say 512MB each) on same disk (file1, file2) and
35 launch two dd threads in different cgroup to read those files.
36
37 sync
38 echo 3 > /proc/sys/vm/drop_caches
39
40 dd if=/mnt/sdb/zerofile1 of=/dev/null &
41 echo $! > /cgroup/test1/tasks
42 cat /cgroup/test1/tasks
43
44 dd if=/mnt/sdb/zerofile2 of=/dev/null &
45 echo $! > /cgroup/test2/tasks
46 cat /cgroup/test2/tasks
47
48- At macro level, first dd should finish first. To get more precise data, keep
49 on looking at (with the help of script), at blkio.disk_time and
50 blkio.disk_sectors files of both test1 and test2 groups. This will tell how
51 much disk time (in milli seconds), each group got and how many secotors each
52 group dispatched to the disk. We provide fairness in terms of disk time, so
53 ideally io.disk_time of cgroups should be in proportion to the weight.
54
55Various user visible config options
56===================================
57CONFIG_CFQ_GROUP_IOSCHED
58 - Enables group scheduling in CFQ. Currently only 1 level of group
59 creation is allowed.
60
61CONFIG_DEBUG_CFQ_IOSCHED
62 - Enables some debugging messages in blktrace. Also creates extra
63 cgroup file blkio.dequeue.
64
65Config options selected automatically
66=====================================
67These config options are not user visible and are selected/deselected
68automatically based on IO scheduler configuration.
69
70CONFIG_BLK_CGROUP
71 - Block IO controller. Selected by CONFIG_CFQ_GROUP_IOSCHED.
72
73CONFIG_DEBUG_BLK_CGROUP
74 - Debug help. Selected by CONFIG_DEBUG_CFQ_IOSCHED.
75
76Details of cgroup files
77=======================
78- blkio.weight
79 - Specifies per cgroup weight.
80
81 Currently allowed range of weights is from 100 to 1000.
82
83- blkio.time
84 - disk time allocated to cgroup per device in milliseconds. First
85 two fields specify the major and minor number of the device and
86 third field specifies the disk time allocated to group in
87 milliseconds.
88
89- blkio.sectors
90 - number of sectors transferred to/from disk by the group. First
91 two fields specify the major and minor number of the device and
92 third field specifies the number of sectors transferred by the
93 group to/from the device.
94
95- blkio.dequeue
96 - Debugging aid only enabled if CONFIG_DEBUG_CFQ_IOSCHED=y. This
97 gives the statistics about how many a times a group was dequeued
98 from service tree of the device. First two fields specify the major
99 and minor number of the device and third field specifies the number
100 of times a group was dequeued from a particular device.
101
102CFQ sysfs tunable
103=================
104/sys/block/<disk>/queue/iosched/group_isolation
105
106If group_isolation=1, it provides stronger isolation between groups at the
107expense of throughput. By default group_isolation is 0. In general that
108means that if group_isolation=0, expect fairness for sequential workload
109only. Set group_isolation=1 to see fairness for random IO workload also.
110
111Generally CFQ will put random seeky workload in sync-noidle category. CFQ
112will disable idling on these queues and it does a collective idling on group
113of such queues. Generally these are slow moving queues and if there is a
114sync-noidle service tree in each group, that group gets exclusive access to
115disk for certain period. That means it will bring the throughput down if
116group does not have enough IO to drive deeper queue depths and utilize disk
117capacity to the fullest in the slice allocated to it. But the flip side is
118that even a random reader should get better latencies and overall throughput
119if there are lots of sequential readers/sync-idle workload running in the
120system.
121
122If group_isolation=0, then CFQ automatically moves all the random seeky queues
123in the root group. That means there will be no service differentiation for
124that kind of workload. This leads to better throughput as we do collective
125idling on root sync-noidle tree.
126
127By default one should run with group_isolation=0. If that is not sufficient
128and one wants stronger isolation between groups, then set group_isolation=1
129but this will come at cost of reduced throughput.
130
131What works
132==========
133- Currently only sync IO queues are support. All the buffered writes are
134 still system wide and not per group. Hence we will not see service
135 differentiation between buffered writes between groups.
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-15 18:12:20 -0500