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>

diff --git a/tools/ocaml/xenstored/connections.ml b/tools/ocaml/xenstored/connections.ml
index f9bc225a0609b04f68b35f189adfe8d4b14ca1c6..ae7692819d66620052a66ac4df0d55729d9b279a 100644 (file)
--- 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 df1e91c6a64c2a765f6a1d748a8d42dc1ef31ead..016ef180f8c43e59e0acf68a4c20b29c83ddffd8 100644 (file)
--- 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 041d22203146be8a8224e819bf1a04bf76947c7a..63c6ad5daa689f89ab1dbd92b1ff719f1191939b 100644 (file)
--- 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 b/tools/ocaml/xenstored/oxenstored.conf
index a100936c719bf016d36fa80d1f7b4e5c3e689795..dd9649beaa44e8b4e15c9a686212f2f63c57edb1 100644 (file)
--- a/tools/ocaml/xenstored/oxenstored.conf
+++ b/tools/ocaml/xenstored/oxenstored.conf
@@ -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 ea511de42369d65636f1f7f91a38b5f30d81bf5a..9480b215a4d5f711678fc962c5ba017918f81741 100644 (file)
--- 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
@@ -393,23 +411,34 @@ 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
                        Unix.select (spec_fds @ inset) outset [] timeout
@@ -419,6 +448,7 @@ 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 (
@@ -426,6 +456,7 @@ let _ =
                        if now > !period_start +. period_ops_interval then
                                (period_start := now; periodic_ops now)
                );
+
                process_domains store cons domains
                in