From c725281e3a2ae0a60c3b181cc469d163315965bb Mon Sep 17 00:00:00 2001 From: Pau Ruiz Safont Date: Thu, 3 Jul 2025 11:50:38 +0100 Subject: [PATCH] xapi-stdext-threads: calibrate ratio for delay times On very busy systems, the wait may take much longer than expected. Instead of hard-coding the expected value, wait once to estimate the time aded to the delays, and then use it to compare the times. Also change to use Mtime.Spans instead of using integers. Signed-off-by: Pau Ruiz Safont --- .../lib/xapi-stdext-threads/scheduler_test.ml | 94 +++++++++++-------- 1 file changed, 55 insertions(+), 39 deletions(-) diff --git a/ocaml/libs/xapi-stdext/lib/xapi-stdext-threads/scheduler_test.ml b/ocaml/libs/xapi-stdext/lib/xapi-stdext-threads/scheduler_test.ml index 0a4a847403f..259a24ee260 100644 --- a/ocaml/libs/xapi-stdext/lib/xapi-stdext-threads/scheduler_test.ml +++ b/ocaml/libs/xapi-stdext/lib/xapi-stdext-threads/scheduler_test.ml @@ -14,90 +14,106 @@ module Scheduler = Xapi_stdext_threads_scheduler.Scheduler +let calibrated_ratio () = + let expected = Mtime.Span.(100 * ms |> to_float_ns) in + let elapsed = Mtime_clock.counter () in + (* Add a 10% leeway to the ratio calculated *) + Thread.delay 0.11 ; + let actual = Mtime_clock.count elapsed |> Mtime.Span.to_float_ns in + let ratio = actual /. expected in + Alcotest.(check bool) (Printf.sprintf "ratio is %f" ratio) true true ; + ratio + let started = Atomic.make false let start_schedule () = if not (Atomic.exchange started true) then Thread.create Scheduler.loop () |> ignore -let send event data = Event.(send event data |> sync) +let send event data () = Event.(send event data |> sync) let receive event = Event.(receive event |> sync) -let elapsed_ms cnt = - let elapsed_ns = Mtime_clock.count cnt |> Mtime.Span.to_uint64_ns in - Int64.(div elapsed_ns 1000000L |> to_int) +let is_less ratio a b = + let a = + Mtime.Span.to_float_ns a + |> Float.mul ratio + |> Int64.of_float + |> Mtime.Span.of_uint64_ns + in + Mtime.Span.is_shorter ~than:a b -let is_less = Alcotest.(testable (pp int)) Stdlib.( > ) +let mtime_span () = + let cmp = is_less (calibrated_ratio ()) in + Alcotest.(testable Mtime.Span.pp) cmp let test_single () = let finished = Event.new_channel () in - Scheduler.add_to_queue "one" Scheduler.OneShot 0.001 (fun () -> - send finished true - ) ; + Scheduler.add_to_queue "one" Scheduler.OneShot 0.001 (send finished true) ; start_schedule () ; Alcotest.(check bool) "result" true (receive finished) -let test_remove_self () = +let test_remove_self mtime_span () = let which = Event.new_channel () in Scheduler.add_to_queue "self" (Scheduler.Periodic 0.001) 0.001 (fun () -> (* this should remove the periodic scheduling *) Scheduler.remove_from_queue "self" ; (* add an operation to stop the test *) - Scheduler.add_to_queue "stop" Scheduler.OneShot 0.1 (fun () -> - send which "stop" - ) ; - send which "self" + Scheduler.add_to_queue "stop" Scheduler.OneShot 0.1 (send which "stop") ; + send which "self" () ) ; start_schedule () ; - let cnt = Mtime_clock.counter () in + + let from_wait_to_receive = Mtime_clock.counter () in Alcotest.(check string) "same event name" "self" (receive which) ; Alcotest.(check string) "same event name" "stop" (receive which) ; - let elapsed_ms = elapsed_ms cnt in - Alcotest.check is_less "small time" 300 elapsed_ms -let test_empty () = + let elapsed = Mtime_clock.count from_wait_to_receive in + let expected = Mtime.Span.(300 * ms) in + Alcotest.check mtime_span "small time" expected elapsed + +let test_empty mtime_span () = let finished = Event.new_channel () in - Scheduler.add_to_queue "one" Scheduler.OneShot 0.001 (fun () -> - send finished true - ) ; + Scheduler.add_to_queue "one" Scheduler.OneShot 0.001 (send finished true) ; start_schedule () ; Alcotest.(check bool) "finished" true (receive finished) ; (* wait loop to go to wait with no work to do *) Thread.delay 0.1 ; - Scheduler.add_to_queue "two" Scheduler.OneShot 0.001 (fun () -> - send finished true - ) ; - let cnt = Mtime_clock.counter () in + Scheduler.add_to_queue "two" Scheduler.OneShot 0.001 (send finished true) ; + + let from_wait_to_receive = Mtime_clock.counter () in Alcotest.(check bool) "finished" true (receive finished) ; - let elapsed_ms = elapsed_ms cnt in - Alcotest.check is_less "small time" 100 elapsed_ms -let test_wakeup () = + let elapsed = Mtime_clock.count from_wait_to_receive in + let expected = Mtime.Span.(100 * ms) in + Alcotest.check mtime_span "small time" expected elapsed + +let test_wakeup mtime_span () = let which = Event.new_channel () in (* schedule a long event *) - Scheduler.add_to_queue "long" Scheduler.OneShot 2.0 (fun () -> - send which "long" - ) ; + Scheduler.add_to_queue "long" Scheduler.OneShot 2.0 (send which "long") ; start_schedule () ; (* wait loop to go to wait with no work to do *) Thread.delay 0.1 ; - let cnt = Mtime_clock.counter () in + (* schedule a quick event, should wake up the loop *) - Scheduler.add_to_queue "quick" Scheduler.OneShot 0.1 (fun () -> - send which "quick" - ) ; + Scheduler.add_to_queue "quick" Scheduler.OneShot 0.1 (send which "quick") ; + + let from_wait_to_receive_quick = Mtime_clock.counter () in Alcotest.(check string) "same event name" "quick" (receive which) ; + Scheduler.remove_from_queue "long" ; - let elapsed_ms = elapsed_ms cnt in - Alcotest.check is_less "small time" 150 elapsed_ms + let elapsed = Mtime_clock.count from_wait_to_receive_quick in + let expected = Mtime.Span.(100 * ms) in + Alcotest.check mtime_span "small time" expected elapsed let tests = + let mtime_span = mtime_span () in [ ("test_single", `Quick, test_single) - ; ("test_remove_self", `Quick, test_remove_self) - ; ("test_empty", `Quick, test_empty) - ; ("test_wakeup", `Quick, test_wakeup) + ; ("test_remove_self", `Quick, test_remove_self mtime_span) + ; ("test_empty", `Quick, test_empty mtime_span) + ; ("test_wakeup", `Quick, test_wakeup mtime_span) ] let () = Alcotest.run "Scheduler" [("generic", tests)]