linux-kernel - [patch] sched: optimize activate

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:	Tue, 14 Nov 2006 15:41:54 -0800
From:	"Chen, Kenneth W" <kenneth.w.chen@...el.com>
To:	<nickpiggin@...oo.com.au>, "Ingo Molnar" <mingo@...e.hu>,
	"Siddha, Suresh B" <suresh.b.siddha@...el.com>
Cc:	<linux-kernel@...r.kernel.org>
Subject: [patch] sched: optimize activate_task for RT task

RT task does not participate in interactiveness priority and thus
shouldn't be bothered with timestamp when task is being put on run
queue. We should push all of the time calculation inside already
existed if (!rt_task) block.


Signed-off-by: Ken Chen <kenneth.w.chen@...el.com>

--- ./kernel/sched.c.orig	2006-11-14 13:29:37.000000000 -0800
+++ ./kernel/sched.c	2006-11-14 13:52:02.000000000 -0800
@@ -936,20 +936,19 @@ static int recalc_task_prio(struct task_
  */
 static void activate_task(struct task_struct *p, struct rq *rq, int local)
 {
-	unsigned long long now;
-
-	now = sched_clock();
+	if (!rt_task(p)) {
+		unsigned long long now = sched_clock();
 #ifdef CONFIG_SMP
-	if (!local) {
-		/* Compensate for drifting sched_clock */
-		struct rq *this_rq = this_rq();
-		now = (now - this_rq->timestamp_last_tick)
-			+ rq->timestamp_last_tick;
-	}
+		if (!local) {
+			/* Compensate for drifting sched_clock */
+			struct rq *this_rq = this_rq();
+			now = (now - this_rq->timestamp_last_tick)
+				+ rq->timestamp_last_tick;
+		}
 #endif
-
-	if (!rt_task(p))
 		p->prio = recalc_task_prio(p, now);
+		p->timestamp = now;
+	}
 
 	/*
 	 * This checks to make sure it's not an uninterruptible task
@@ -973,7 +972,6 @@ static void activate_task(struct task_st
 			p->sleep_type = SLEEP_INTERACTIVE;
 		}
 	}
-	p->timestamp = now;
 
 	__activate_task(p, 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/