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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Eric Dumazet <edumazet@google.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Chris Mason <clm@fb.com>, Arjan van de Ven <arjan@infradead.org>,
	rt@linutronix.de, Rik van Riel <riel@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	George Spelvin <linux@sciencehorizons.net>,
	Len Brown <lenb@kernel.org>,
	Josh Triplett <josh@joshtriplett.org>
Subject: [patch V3 18/22] tick/sched: Remove pointless empty function
Date: Fri, 24 Jun 2016 14:32:18 -0000	[thread overview]
Message-ID: <20160624141722.929241287@linutronix.de> (raw)
In-Reply-To: <20160624140325.554996200@linutronix.de>

[-- Attachment #1: ticksched_Remove_pointless_empty_function.patch --]
[-- Type: text/plain, Size: 2021 bytes --]

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@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Chris Mason <clm@fb.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: rt@linutronix.de
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Arjan van de Ven <arjan@infradead.org>

---
 kernel/time/tick-sched.c |   33 +--------------------------------
 1 file changed, 1 insertion(+), 32 deletions(-)

--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1092,35 +1092,6 @@ static void tick_nohz_switch_to_nohz(voi
 	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(v
 	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

  parent reply	other threads:[~2016-06-24 14:36 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-24 14:32 [patch V3 00/22] timer: Refactor the timer wheel Thomas Gleixner
2016-06-24 14:32 ` [patch V3 01/22] timer: Make pinned a timer property Thomas Gleixner
2016-07-01 13:03   ` Frederic Weisbecker
2016-06-24 14:32 ` [patch V3 02/22] x86/apic/uv: Initialize timer as pinned Thomas Gleixner
2016-06-24 14:32 ` [patch V3 03/22] x86/mce: " Thomas Gleixner
2016-06-24 14:32 ` [patch V3 04/22] cpufreq/powernv: " Thomas Gleixner
2016-06-24 14:32 ` [patch V3 05/22] driver/net/ethernet/tile: " Thomas Gleixner
2016-06-24 14:32 ` [patch V3 06/22] drivers/tty/metag_da: " Thomas Gleixner
2016-06-24 14:32 ` [patch V3 07/22] drivers/tty/mips_ejtag: " Thomas Gleixner
2016-06-24 14:32 ` [patch V3 08/22] net/ipv4/inet: Initialize timers " Thomas Gleixner
2016-06-24 14:32 ` [patch V3 09/22] timer: Remove mod_timer_pinned Thomas Gleixner
2016-06-24 14:32 ` [patch V3 10/22] signal: Use hrtimer for sigtimedwait Thomas Gleixner
2016-06-24 14:32 ` [patch V3 11/22] hlist: Add hlist_is_singular_node() helper Thomas Gleixner
2016-06-24 14:32 ` [patch V3 12/22] timer: Give a few structs and members proper names Thomas Gleixner
2016-06-24 14:32 ` [patch V3 13/22] timer: Reduce the CPU index space to 256k Thomas Gleixner
2016-07-01 14:41   ` Frederic Weisbecker
2016-06-24 14:32 ` [patch V3 14/22] timer: Switch to a non cascading wheel Thomas Gleixner
2016-06-24 14:32 ` [patch V3 15/22] timer: Remove slack leftovers Thomas Gleixner
2016-06-24 14:32 ` [patch V3 16/22] timer: Move __run_timers() function Thomas Gleixner
2016-06-24 14:32 ` [patch V3 17/22] timer: Optimize collect timers for NOHZ Thomas Gleixner
2016-06-24 14:32 ` Thomas Gleixner [this message]
2016-06-24 14:32 ` [patch V3 19/22] timer: Forward wheel clock whenever possible Thomas Gleixner
2016-06-24 20:45   ` Richard Cochran
2016-06-25  8:55     ` Thomas Gleixner
2016-06-24 14:32 ` [patch V3 20/22] timer: Only wake softirq if necessary Thomas Gleixner
2016-06-24 14:32 ` [patch V3 21/22] timer: Split out index calculation Thomas Gleixner
2016-06-24 14:32 ` [patch V3 22/22] timer: Optimization for same expiry time in mod_timer() Thomas Gleixner
2016-06-24 17:04 ` [patch V3 00/22] timer: Refactor the timer wheel Josh Triplett
2016-06-27  4:22 ` Paul E. McKenney
2016-06-27 23:56   ` Paul E. McKenney

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