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
