[Xen-changelog] [xen stable-4.6] oxenstored transaction conflicts: improve logging

[patchbot@xxxxxxx]

commit f0f3d439b13248999a9d0ddf5cd69d17cc0084fb
Author:     Thomas Sanders <thomas.sanders@xxxxxxxxxx>
AuthorDate: Mon Mar 27 14:36:34 2017 +0100
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Wed Apr 5 15:19:02 2017 +0100

    oxenstored transaction conflicts: improve logging
    
    For information related to transaction conflicts, potentially frequent
    logging at "info" priority has been changed to "debug" priority, and
    once per two minutes there is an "info" priority summary.
    
    Additional detailed logging has been added at "debug" priority.
    
    Reported-by: Juergen Gross <jgross@xxxxxxxx>
    Signed-off-by: Thomas Sanders <thomas.sanders@xxxxxxxxxx>
---
 tools/ocaml/xenstored/domain.ml      | 8 ++++++++
 tools/ocaml/xenstored/domains.ml     | 5 +++++
 tools/ocaml/xenstored/process.ml     | 6 +++++-
 tools/ocaml/xenstored/transaction.ml | 5 +++++
 tools/ocaml/xenstored/xenstored.ml   | 6 ++++++
 5 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/tools/ocaml/xenstored/domain.ml b/tools/ocaml/xenstored/domain.ml
index e677aa3..4515650 100644
--- a/tools/ocaml/xenstored/domain.ml
+++ b/tools/ocaml/xenstored/domain.ml
@@ -34,6 +34,7 @@ type t =
        mutable conflict_credit: float; (* Must be positive to perform writes; 
a commit
                                           that later causes conflict with 
another
                                           domain's transaction costs credit. *)
+       mutable caused_conflicts: int64;
 }
 
 let is_dom0 d = d.id = 0
@@ -93,4 +94,11 @@ let make id mfn remote_port interface eventchn = {
        bad_client = false;
        io_credit = 0;
        conflict_credit = !Define.conflict_burst_limit;
+       caused_conflicts = 0L;
 }
+
+let log_and_reset_conflict_stats logfn dom =
+       if dom.caused_conflicts > 0L then (
+               logfn dom.id dom.caused_conflicts;
+               dom.caused_conflicts <- 0L
+       )
diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
index 25fd592..ca749fa 100644
--- a/tools/ocaml/xenstored/domains.ml
+++ b/tools/ocaml/xenstored/domains.ml
@@ -148,8 +148,10 @@ let create0 fake doms =
        dom
 
 let decr_conflict_credit doms dom =
+       dom.Domain.caused_conflicts <- Int64.add 1L dom.Domain.caused_conflicts;
        let before = dom.Domain.conflict_credit in
        let after = max (-1.0) (before -. 1.0) in
+       debug "decr_conflict_credit dom%d %F -> %F" (Domain.get_id dom) before 
after;
        dom.Domain.conflict_credit <- after;
        let newly_penalised =
                before >= !Define.conflict_burst_limit
@@ -180,7 +182,9 @@ let decr_conflict_credit doms dom =
 let incr_conflict_credit_from_queue doms =
        let process_queue q requeue_test =
                let d = pop q in
+               let before = d.Domain.conflict_credit in (* just for 
debug-logging *)
                d.Domain.conflict_credit <- min (d.Domain.conflict_credit +. 
1.0) !Define.conflict_burst_limit;
+               debug "incr_conflict_credit_from_queue: dom%d: %F -> %F" 
(Domain.get_id d) before d.Domain.conflict_credit;
                if requeue_test d.Domain.conflict_credit then (
                        push d q (* Make it queue up again for its next point 
of credit. *)
                )
@@ -202,6 +206,7 @@ let incr_conflict_credit doms =
                        let before = dom.Domain.conflict_credit in
                        let after = min (before +. 1.0) 
!Define.conflict_burst_limit in
                        dom.Domain.conflict_credit <- after;
+                       debug "incr_conflict_credit dom%d: %F -> %F" 
(Domain.get_id dom) before after;
 
                        if before <= 0.0 && after > 0.0
                        then doms.n_paused <- doms.n_paused - 1;
diff --git a/tools/ocaml/xenstored/process.ml b/tools/ocaml/xenstored/process.ml
index adfc7a4..8a688c4 100644
--- a/tools/ocaml/xenstored/process.ml
+++ b/tools/ocaml/xenstored/process.ml
@@ -330,6 +330,7 @@ let transaction_replay c t doms cons =
                                Transaction.commit ~con replay_t
                        with
                        | Transaction_again -> (
+                               Transaction.failed_commits := Int64.add 
!Transaction.failed_commits 1L;
                                let victim_domstr = Connection.get_domstr c in
                                debug "Apportioning blame for EAGAIN in txn %d, 
domain=%s" id victim_domstr;
                                let punish guilty_con =
@@ -351,7 +352,10 @@ let transaction_replay c t doms cons =
                                        else false
                                ) in
                                let guilty_cons = History.filter_connections 
~ignore:c ~since:t.Transaction.start_count ~f:judge_and_sentence in
-                               if Hashtbl.length guilty_cons = 0 then debug 
"Found no culprit for conflict in %s: must be self or not in history." con;
+                               if Hashtbl.length guilty_cons = 0 then (
+                                       debug "Found no culprit for conflict in 
%s: must be self or not in history." con;
+                                       Transaction.failed_commits_no_culprit 
:= Int64.add !Transaction.failed_commits_no_culprit 1L
+                               );
                                false
                        )
                        | e ->
diff --git a/tools/ocaml/xenstored/transaction.ml 
b/tools/ocaml/xenstored/transaction.ml
index 8f95301..da4a3e3 100644
--- a/tools/ocaml/xenstored/transaction.ml
+++ b/tools/ocaml/xenstored/transaction.ml
@@ -90,6 +90,11 @@ type t = {
 let get_id t = match t.ty with No -> none | Full (id, _, _) -> id
 
 let counter = ref 0L
+let failed_commits = ref 0L
+let failed_commits_no_culprit = ref 0L
+let reset_conflict_stats () =
+       failed_commits := 0L;
+       failed_commits_no_culprit := 0L
 
 (* Scope for optimisation: different data-structure and functions to 
search/filter it *)
 let short_running_txns = ref []
diff --git a/tools/ocaml/xenstored/xenstored.ml 
b/tools/ocaml/xenstored/xenstored.ml
index 03e19bb..a481d80 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -377,6 +377,7 @@ let _ =
        let last_scan_time = ref 0. in
 
        let periodic_ops now =
+               debug "periodic_ops starting";
                (* we garbage collect the string->int dictionary after a 
sizeable amount of operations,
                 * there's no need to be really fast even if we got loose
                 * objects since names are often reuse.
@@ -396,7 +397,11 @@ let _ =
 
                (* make sure we don't print general stats faster than 2 min *)
                if now > (!last_stat_time +. 120.) then (
+                       info "Transaction conflict statistics for last %F 
seconds:" (now -. !last_stat_time);
                        last_stat_time := now;
+                       Domains.iter domains 
(Domain.log_and_reset_conflict_stats (info "Dom%d caused %Ld conflicts"));
+                       info "%Ld failed transactions; of these no culprit was 
found for %Ld" !Transaction.failed_commits 
!Transaction.failed_commits_no_culprit;
+                       Transaction.reset_conflict_stats ();
 
                        let gc = Gc.stat () in
                        let (lanon, lanon_ops, lanon_watchs,
@@ -416,6 +421,7 @@ let _ =
                             gc.Gc.free_words gc.Gc.free_blocks
                );
                let elapsed = Unix.gettimeofday () -. now in
+               debug "periodic_ops took %F seconds." elapsed;
                delay_next_frequent_ops_by elapsed
        in
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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