linux-kernel - [tip:timers/core] timers/nohz: Remove pointless tick_nohz_kick

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Date:	Thu, 7 Jul 2016 01:47:35 -0700
From:	tip-bot for Thomas Gleixner <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...nel.org, tglx@...utronix.de, paulmck@...ux.vnet.ibm.com,
	lenb@...nel.org, riel@...hat.com, torvalds@...ux-foundation.org,
	arjan@...radead.org, edumazet@...gle.com, peterz@...radead.org,
	linux@...encehorizons.net, clm@...com, josh@...htriplett.org,
	linux-kernel@...r.kernel.org, hpa@...or.com, fweisbec@...il.com
Subject: [tip:timers/core] timers/nohz: Remove pointless
 tick_nohz_kick_tick() function

Commit-ID:  ff00673292bd42a3688b33de47252a6a3c3f424c
Gitweb:     http://git.kernel.org/tip/ff00673292bd42a3688b33de47252a6a3c3f424c
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Mon, 4 Jul 2016 09:50:35 +0000
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 7 Jul 2016 10:35:10 +0200

timers/nohz: Remove pointless tick_nohz_kick_tick() function

This was a failed attempt to optimize the timer expiry in idle, which was
disabled and never revisited. Remove the cruft.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Arjan van de Ven <arjan@...radead.org>
Cc: Chris Mason <clm@...com>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: George Spelvin <linux@...encehorizons.net>
Cc: Josh Triplett <josh@...htriplett.org>
Cc: Len Brown <lenb@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...hat.com>
Cc: rt@...utronix.de
Link: http://lkml.kernel.org/r/20160704094342.431073782@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/time/tick-sched.c | 33 +--------------------------------
 1 file changed, 1 insertion(+), 32 deletions(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 536ada8..69abc7b 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1092,35 +1092,6 @@ static void tick_nohz_switch_to_nohz(void)
 	tick_nohz_activate(ts, NOHZ_MODE_LOWRES);
 }
 
-/*
- * When NOHZ is enabled and the tick is stopped, we need to kick the
- * tick timer from irq_enter() so that the jiffies update is kept
- * alive during long running softirqs. That's ugly as hell, but
- * correctness is key even if we need to fix the offending softirq in
- * the first place.
- *
- * Note, this is different to tick_nohz_restart. We just kick the
- * timer and do not touch the other magic bits which need to be done
- * when idle is left.
- */
-static void tick_nohz_kick_tick(struct tick_sched *ts, ktime_t now)
-{
-#if 0
-	/* Switch back to 2.6.27 behaviour */
-	ktime_t delta;
-
-	/*
-	 * Do not touch the tick device, when the next expiry is either
-	 * already reached or less/equal than the tick period.
-	 */
-	delta =	ktime_sub(hrtimer_get_expires(&ts->sched_timer), now);
-	if (delta.tv64 <= tick_period.tv64)
-		return;
-
-	tick_nohz_restart(ts, now);
-#endif
-}
-
 static inline void tick_nohz_irq_enter(void)
 {
 	struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
@@ -1131,10 +1102,8 @@ static inline void tick_nohz_irq_enter(void)
 	now = ktime_get();
 	if (ts->idle_active)
 		tick_nohz_stop_idle(ts, now);
-	if (ts->tick_stopped) {
+	if (ts->tick_stopped)
 		tick_nohz_update_jiffies(now);
-		tick_nohz_kick_tick(ts, now);
-	}
 }
 
 #else