linux-kernel - [PATCH v2 1/6] sched: only try to push a task on wakeup if it is migratable

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: <20080826173449.16413.89611.stgit@dev.haskins.net>
Date:	Tue, 26 Aug 2008 13:34:49 -0400
From:	Gregory Haskins <ghaskins@...ell.com>
To:	mingo@...e.hu
Cc:	srostedt@...hat.com, peterz@...radead.org,
	linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
	npiggin@...e.de, gregory.haskins@...il.com
Subject: [PATCH v2 1/6] sched: only try to push a task on wakeup if it is
	migratable

There is no sense in wasting time trying to push a task away that
cannot move anywhere else.  We gain no benefit from trying to push
other tasks at this point, so if the task being woken up is non
migratable, just skip the whole operation.  This reduces overhead
in the wakeup path for certain tasks.

Signed-off-by: Gregory Haskins <ghaskins@...ell.com>
---

 kernel/sched_rt.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index 6163e4c..196c024 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1229,14 +1229,16 @@ static void post_schedule_rt(struct rq *rq)
 }
 
 /*
- * If we are not running and we are not going to reschedule soon, we should
- * try to push tasks away now
+ * If we are not running, we are not going to reschedule soon,
+ * and we have tasks that could be pushed, we should try to push tasks
+ * away now
  */
 static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
 {
 	if (!task_running(rq, p) &&
 	    !test_tsk_need_resched(rq->curr) &&
-	    rq->rt.overloaded)
+	    rq->rt.overloaded &&
+	    p->rt.nr_cpus_allowed > 1)
 		push_rt_tasks(rq);
 }
 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/