linux-kernel - [PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

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-next>] [day] [month] [year] [list]

Message-Id: <1416391297-111305-1-git-send-email-wanpeng.li@linux.intel.com>
Date:	Wed, 19 Nov 2014 18:01:36 +0800
From:	Wanpeng Li <wanpeng.li@...ux.intel.com>
To:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	Juri Lelli <juri.lelli@....com>,
	Kirill Tkhai <ktkhai@...allels.com>,
	linux-kernel@...r.kernel.org,
	Wanpeng Li <wanpeng.li@...ux.intel.com>
Subject: [PATCH 1/2] sched/deadline: reduce overhead if there are no scheduling parameters changed

There is no need to dequeue/enqueue and push/pull if there are
no scheduling parameters changed for dl class, actually both 
fair and rt class have already check if parameters changed for 
them to avoid unnecessary overhead. This patch add the parameters 
changed verify for dl class in order to reduce overhead.

Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
---
 kernel/sched/core.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 603c462..f361867 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3402,6 +3402,21 @@ static bool check_same_owner(struct task_struct *p)
 	return match;
 }
 
+static bool dl_param_changed(struct task_struct *p,
+			const struct sched_attr *attr)
+{
+	struct sched_dl_entity *dl_se = &p->dl;
+
+	if (dl_se->dl_runtime != attr->sched_runtime ||
+		dl_se->dl_deadline != attr->sched_deadline ||
+		dl_se->dl_period != attr->sched_period ||
+		dl_se->flags != attr->sched_flags ||
+		p->rt_priority != attr->sched_priority)
+		return true;
+
+	return false;
+}
+
 static int __sched_setscheduler(struct task_struct *p,
 				const struct sched_attr *attr,
 				bool user)
@@ -3530,7 +3545,7 @@ recheck:
 			goto change;
 		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
 			goto change;
-		if (dl_policy(policy))
+		if (dl_policy(policy) && dl_param_changed(p, attr))
 			goto change;
 
 		p->sched_reset_on_fork = reset_on_fork;
-- 
1.9.1

--
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/