oxenstored: only process domain connections that notify us by events

Currently, upon receiving an event, oxenstored will always scan/process all
the domain connections (xs rings), disregarding which domain sent that event.
This is rather costy and inefficient. It also shadows and indulges client
for not correctly communicating with us on message/space availability.

With this patch, oxenstore will only scan/process the domain connections
that have correctly notified us by events or have IO actions leftover from
previous communication.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Zheng Li <dev@zheng.li>
Reviewed-by: David Scott <dave.scott@citrix.com>

diff --git a/tools/ocaml/xenstored/connection.ml b/tools/ocaml/xenstored/connection.ml
index 47695f86bfcbf622a2aa1182f636e7098bb4ecf1..807fc001df8456e74c81082716a81a71edb6b2f3 100644 (file)
--- a/tools/ocaml/xenstored/connection.ml
+++ b/tools/ocaml/xenstored/connection.ml
@@ -223,10 +223,14 @@ let pop_in con = Xenbus.Xb.get_in_packet con.xb
 let has_more_input con = Xenbus.Xb.has_more_input con.xb
 
 let has_output con = Xenbus.Xb.has_output con.xb
+let has_old_output con = Xenbus.Xb.has_old_output con.xb
 let has_new_output con = Xenbus.Xb.has_new_output con.xb
 let peek_output con = Xenbus.Xb.peek_output con.xb
 let do_output con = Xenbus.Xb.output con.xb
 
+let has_more_work con =
+       has_more_input con || not (has_old_output con) && has_new_output con
+
 let incr_ops con = con.stat_nb_ops <- con.stat_nb_ops + 1
 
 let mark_symbols con =

diff --git a/tools/ocaml/xenstored/connections.ml b/tools/ocaml/xenstored/connections.ml
index 1c8d9111abdb7f94cbacb2d80285594a1772cac7..f9bc225a0609b04f68b35f189adfe8d4b14ca1c6 100644 (file)
--- a/tools/ocaml/xenstored/connections.ml
+++ b/tools/ocaml/xenstored/connections.ml
@@ -98,11 +98,10 @@ let iter cons fct =
        iter_domains cons fct; iter_anonymous cons fct
 
 let has_more_work cons =
-       Hashtbl.fold (fun id con acc ->
-               if Connection.has_more_input con then
-                       con :: acc
-               else
-                       acc) cons.domains []
+       Hashtbl.fold
+               (fun id con acc ->
+                if Connection.has_more_work con then con :: acc else acc)
+               cons.domains []
 
 let key_of_str path =
        if path.[0] = '@'

diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
index d74846c64045c4c79c1e31686f45291360e3729f..4a1d0279c156dc4761bc930b42cb2e95b440f64c 100644 (file)
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -57,7 +57,10 @@ let process_domains store cons domains =
                        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 in
-       Domains.iter domains do_io_domain
+       List.iter
+               (fun c ->
+                match Connection.get_domain c with
+                | Some d -> do_io_domain d | _ -> ())
 
 let sigusr1_handler store =
        try
@@ -303,6 +306,7 @@ let _ =
                        Connections.add_anonymous cons cfd can_write
                and handle_eventchn fd =
                        let port = Event.pending eventchn in
+                       debug "pending port %d" (Xeneventchn.to_int port);
                        finally (fun () ->
                                if Some port = eventchn.Event.virq_port then (
                                        let (notify, deaddom) = Domains.cleanup xc domains in
@@ -310,7 +314,10 @@ let _ =
                                        if deaddom <> [] || notify then
                                                Connections.fire_spec_watches cons "@releaseDomain"
                                )
-                       ) (fun () -> Event.unmask eventchn port);
+                               else
+                                       let c = Connections.find_domain_by_port cons port in
+                                       process_domains store cons domains [c]
+                               ) (fun () -> Event.unmask eventchn port)
                and do_if_set fd set fct =
                        if List.mem fd set then
                                fct fd in
@@ -380,7 +387,7 @@ let _ =
                        process_special_fds sfds;
                if List.length cfds > 0 || List.length wset > 0 then
                        process_connection_fds store cons domains cfds wset;
-               process_domains store cons domains
+               process_domains store cons domains mw
                in
 
        while not !quit