linux-kernel - Re: [PATCH v5 6/7] sched/deadline: Deferrable dl server

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3e58fad7-7f66-4e48-adcc-0fda9e9d0d07@kernel.org>
Date:   Tue, 7 Nov 2023 19:50:28 +0100
From:   Daniel Bristot de Oliveira <bristot@...nel.org>
To:     Daniel Bristot de Oliveira <bristot@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>,
        Valentin Schneider <vschneid@...hat.com>,
        linux-kernel@...r.kernel.org,
        Luca Abeni <luca.abeni@...tannapisa.it>,
        Tommaso Cucinotta <tommaso.cucinotta@...tannapisa.it>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vineeth Pillai <vineeth@...byteword.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Phil Auld <pauld@...hat.com>
Subject: Re: [PATCH v5 6/7] sched/deadline: Deferrable dl server

> The code is not doing what I intended because I thought it was doing overload
> control on the replenishment, but it is not (my bad).
> 

I am still testing but... it is missing something like this (famous last words).

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 1092ca8892e0..6e2d21c47a04 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -842,6 +842,8 @@ static inline void setup_new_dl_entity(struct sched_dl_entity *dl_se)
  * runtime, or it just underestimated it during sched_setattr().
  */
 static int start_dl_timer(struct sched_dl_entity *dl_se);
+static bool dl_entity_overflow(struct sched_dl_entity *dl_se, u64 t);
+
 static void replenish_dl_entity(struct sched_dl_entity *dl_se)
 {
 	struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
@@ -852,9 +854,18 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
 	/*
 	 * This could be the case for a !-dl task that is boosted.
 	 * Just go with full inherited parameters.
+	 *
+	 * Or, it could be the case of a zerolax reservation that
+	 * was not able to consume its runtime in background and
+	 * reached this point with current u > U.
+	 *
+	 * In both cases, set a new period.
 	 */
-	if (dl_se->dl_deadline == 0)
-		replenish_dl_new_period(dl_se, rq);
+	if (dl_se->dl_deadline == 0 ||
+		(dl_se->dl_zerolax_armed && dl_entity_overflow(dl_se, rq_clock(rq)))) {
+			dl_se->deadline = rq_clock(rq) + pi_of(dl_se)->dl_deadline;
+			dl_se->runtime = pi_of(dl_se)->dl_runtime;
+	}

 	if (dl_se->dl_yielded && dl_se->runtime > 0)
 		dl_se->runtime = 0;