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
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
From e0f02f8fb5a5130a37bd7efdc80d7f0dd46db41e Mon Sep 17 00:00:00 2001
From: Thomas Sanders <thomas.sanders@citrix.com>
Date: Tue, 14 Mar 2017 12:15:52 +0000
Subject: [PATCH 05/15] oxenstored: ignore domains with no conflict-credit
When processing connections, skip those from domains with no remaining
conflict-credit.
Also, issue a point of conflict-credit at regular intervals, the
period being set by the configuration option "conflict-max-history-
seconds". When issuing conflict-credit, we give a point either to
every domain at once (one each) or only to the single domain at the
front of the queue, depending on the configuration option
"conflict-rate-limit-is-aggregate".
Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Reviewed-by: Jonathan Davies <jonathan.davies@citrix.com>
Reviewed-by: Christian Lindig <christian.lindig@citrix.com>
---
tools/ocaml/xenstored/connections.ml | 14 ++++---
tools/ocaml/xenstored/define.ml | 1 +
tools/ocaml/xenstored/domains.ml | 4 +-
tools/ocaml/xenstored/oxenstored.conf.in | 2 +-
tools/ocaml/xenstored/xenstored.ml | 65 +++++++++++++++++++++++---------
5 files changed, 60 insertions(+), 26 deletions(-)
diff --git a/tools/ocaml/xenstored/connections.ml b/tools/ocaml/xenstored/connections.ml
index f9bc225..ae76928 100644
--- a/tools/ocaml/xenstored/connections.ml
+++ b/tools/ocaml/xenstored/connections.ml
@@ -44,12 +44,14 @@ let add_domain cons dom =
| Some p -> Hashtbl.add cons.ports p con;
| None -> ()
-let select cons =
- Hashtbl.fold
- (fun _ con (ins, outs) ->
- let fd = Connection.get_fd con in
- (fd :: ins, if Connection.has_output con then fd :: outs else outs))
- cons.anonymous ([], [])
+let select ?(only_if = (fun _ -> true)) cons =
+ Hashtbl.fold (fun _ con (ins, outs) ->
+ if (only_if con) then (
+ let fd = Connection.get_fd con in
+ (fd :: ins, if Connection.has_output con then fd :: outs else outs)
+ ) else (ins, outs)
+ )
+ cons.anonymous ([], [])
let find cons =
Hashtbl.find cons.anonymous
diff --git a/tools/ocaml/xenstored/define.ml b/tools/ocaml/xenstored/define.ml
index 816b493..5a604d1 100644
--- a/tools/ocaml/xenstored/define.ml
+++ b/tools/ocaml/xenstored/define.ml
@@ -30,6 +30,7 @@ let maxtransaction = ref (20)
let maxrequests = ref (-1) (* maximum requests per transaction *)
let conflict_burst_limit = ref 5.0
+let conflict_max_history_seconds = ref 0.05
let conflict_rate_limit_is_aggregate = ref true
let domid_self = 0x7FF0
diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
index 3d29cc8..99f68c7 100644
--- a/tools/ocaml/xenstored/domains.ml
+++ b/tools/ocaml/xenstored/domains.ml
@@ -39,12 +39,12 @@ type domains = {
mutable n_paused: int;
}
-let init eventchn = {
+let init eventchn on_first_conflict_pause = {
eventchn = eventchn;
table = Hashtbl.create 10;
doms_conflict_paused = Queue.create ();
doms_with_conflict_penalty = Queue.create ();
- on_first_conflict_pause = (fun () -> ()); (* Dummy value for now, pending subsequent commit. *)
+ on_first_conflict_pause = on_first_conflict_pause;
n_paused = 0;
}
let del doms id = Hashtbl.remove doms.table id
diff --git a/tools/ocaml/xenstored/oxenstored.conf.in b/tools/ocaml/xenstored/oxenstored.conf.in
index edd4335..536611e 100644
--- a/tools/ocaml/xenstored/oxenstored.conf.in
+++ b/tools/ocaml/xenstored/oxenstored.conf.in
@@ -22,7 +22,7 @@ conflict-burst-limit = 5.0
# The conflict-credit is replenished over time:
# one point is issued after each conflict-max-history-seconds, so this
# is the minimum pause-time during which a domain will be ignored.
-# conflict-max-history-seconds = 0.05
+conflict-max-history-seconds = 0.05
# If the conflict-rate-limit-is-aggregate flag is true then after each
# tick one point of conflict-credit is given to just one domain: the
diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
index 20473d5..f562f59 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -53,14 +53,16 @@ let process_connection_fds store cons domains rset wset =
let process_domains store cons domains =
let do_io_domain domain =
- if not (Domain.is_bad_domain domain) then
- let io_credit = Domain.get_io_credit domain in
- if io_credit > 0 then (
- let con = Connections.find_domain cons (Domain.get_id domain) in
- Process.do_input store cons domains con;
- Process.do_output store cons domains con;
- Domain.decr_io_credit domain;
- ) in
+ if Domain.is_bad_domain domain
+ || Domain.get_io_credit domain <= 0
+ || Domain.is_paused_for_conflict domain
+ then () (* nothing to do *)
+ else (
+ let con = Connections.find_domain cons (Domain.get_id domain) in
+ Process.do_input store cons domains con;
+ Process.do_output store cons domains con;
+ Domain.decr_io_credit domain
+ ) in
Domains.iter domains do_io_domain
let sigusr1_handler store =
@@ -90,6 +92,7 @@ let parse_config filename =
let options = [
("merge-activate", Config.Set_bool Transaction.do_coalesce);
("conflict-burst-limit", Config.Set_float Define.conflict_burst_limit);
+ ("conflict-max-history-seconds", Config.Set_float Define.conflict_max_history_seconds);
("conflict-rate-limit-is-aggregate", Config.Set_bool Define.conflict_rate_limit_is_aggregate);
("perms-activate", Config.Set_bool Perms.activate);
("quota-activate", Config.Set_bool Quota.activate);
@@ -262,7 +265,22 @@ let _ =
let store = Store.create () in
let eventchn = Event.init () in
- let domains = Domains.init eventchn in
+ let next_frequent_ops = ref 0. in
+ let advance_next_frequent_ops () =
+ next_frequent_ops := (Unix.gettimeofday () +. !Define.conflict_max_history_seconds)
+ in
+ let delay_next_frequent_ops_by duration =
+ next_frequent_ops := !next_frequent_ops +. duration
+ in
+ let domains = Domains.init eventchn advance_next_frequent_ops in
+
+ (* For things that need to be done periodically but more often
+ * than the periodic_ops function *)
+ let frequent_ops () =
+ if Unix.gettimeofday () > !next_frequent_ops then (
+ Domains.incr_conflict_credit domains;
+ advance_next_frequent_ops ()
+ ) in
let cons = Connections.create () in
let quit = ref false in
@@ -394,23 +412,34 @@ let _ =
gc.Gc.heap_words gc.Gc.heap_chunks
gc.Gc.live_words gc.Gc.live_blocks
gc.Gc.free_words gc.Gc.free_blocks
- )
- in
+ );
+ let elapsed = Unix.gettimeofday () -. now in
+ delay_next_frequent_ops_by elapsed
+ in
- let period_ops_interval = 15. in
- let period_start = ref 0. in
+ let period_ops_interval = 15. in
+ let period_start = ref 0. in
let main_loop () =
-
+ let is_peaceful c =
+ match Connection.get_domain c with
+ | None -> true (* Treat socket-connections as exempt, and free to conflict. *)
+ | Some dom -> not (Domain.is_paused_for_conflict dom)
+ in
+ frequent_ops ();
let mw = Connections.has_more_work cons in
+ let peaceful_mw = List.filter is_peaceful mw in
List.iter
(fun c ->
match Connection.get_domain c with
| None -> () | Some d -> Domain.incr_io_credit d)
- mw;
+ peaceful_mw;
+ let start_time = Unix.gettimeofday () in
let timeout =
- if List.length mw > 0 then 0. else period_ops_interval in
- let inset, outset = Connections.select cons in
+ let until_next_activity = min (max 0. (!next_frequent_ops -. start_time)) period_ops_interval in
+ if peaceful_mw <> [] then 0. else until_next_activity
+ in
+ let inset, outset = Connections.select ~only_if:is_peaceful cons in
let rset, wset, _ =
try
Select.select (spec_fds @ inset) outset [] timeout
@@ -420,6 +449,7 @@ let _ =
List.partition (fun fd -> List.mem fd spec_fds) rset in
if List.length sfds > 0 then
process_special_fds sfds;
+
if List.length cfds > 0 || List.length wset > 0 then
process_connection_fds store cons domains cfds wset;
if timeout <> 0. then (
@@ -427,6 +457,7 @@ let _ =
if now > !period_start +. period_ops_interval then
(period_start := now; periodic_ops now)
);
+
process_domains store cons domains
in
--
2.1.4
|
