linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Anna-Maria Gleixner <anna-maria@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>
Subject: [RFC PATCH 06/10] timer: Reuse next expiry cache after nohz exit
Date: Wed,  1 Jul 2020 03:10:26 +0200	[thread overview]
Message-ID: <20200701011030.14324-7-frederic@kernel.org> (raw)
In-Reply-To: <20200701011030.14324-1-frederic@kernel.org>

Now that we track the next expiry unconditionally when a timer is added,
we can reuse that information on a tick firing after exiting nohz.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Juri Lelli <juri.lelli@redhat.com>
---
 kernel/time/timer.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 30f491ec875a..4612d26fd09a 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1697,13 +1697,11 @@ static int collect_expired_timers(struct timer_base *base,
 	 * the next expiring timer.
 	 */
 	if ((long)(now - base->clk) > 2) {
-		unsigned long next = __next_timer_interrupt(base);
-
 		/*
 		 * If the next timer is ahead of time forward to current
 		 * jiffies, otherwise forward to the next expiry time:
 		 */
-		if (time_after(next, now)) {
+		if (time_after(base->next_expiry, now)) {
 			/*
 			 * The call site will increment base->clk and then
 			 * terminate the expiry loop immediately.
@@ -1711,7 +1709,7 @@ static int collect_expired_timers(struct timer_base *base,
 			base->clk = now;
 			return 0;
 		}
-		base->clk = next;
+		base->clk = base->next_expiry;
 	}
 	return __collect_expired_timers(base, heads);
 }
-- 
2.26.2


  parent reply	other threads:[~2020-07-01  1:11 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-01  1:10 [RFC PATCH 00/10] timer: Reduce timers softirq (and other optimizations) Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 01/10] timer: Prevent base->clk from moving backward Frederic Weisbecker
2020-07-01 16:35   ` Juri Lelli
2020-07-01 23:20     ` Frederic Weisbecker
2020-07-02  9:59       ` Juri Lelli
2020-07-02 14:04         ` Frederic Weisbecker
2020-07-02 14:32         ` Frederic Weisbecker
2020-07-02 15:57           ` Juri Lelli
2020-07-02  9:48   ` Thomas Gleixner
2020-07-01  1:10 ` [RFC PATCH 02/10] timer: Move trigger_dyntick_cpu() to enqueue_timer() Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 03/10] timer: Simplify LVL_START() and calc_index() Frederic Weisbecker
2020-07-02 11:59   ` Thomas Gleixner
2020-07-02 12:27     ` Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 04/10] timer: Optimize _next_timer_interrupt() level iteration Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 05/10] timers: Always keep track of next expiry Frederic Weisbecker
2020-07-01  1:10 ` Frederic Weisbecker [this message]
2020-07-01  1:10 ` [RFC PATCH 07/10] timer: Expand clk forward logic beyond nohz Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 08/10] timer: Spare timer softirq until next expiry Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 09/10] timer: Remove must_forward_clk Frederic Weisbecker
2020-07-01  1:10 ` [RFC PATCH 10/10] timer: Lower base clock forwarding threshold Frederic Weisbecker
2020-07-02 13:21   ` Thomas Gleixner
2020-07-02 13:32     ` Frederic Weisbecker
2020-07-02 15:14       ` Thomas Gleixner
2020-07-03  0:12         ` Frederic Weisbecker
2020-07-03  9:13           ` Thomas Gleixner

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200701011030.14324-7-frederic@kernel.org \
    --to=frederic@kernel.org \
    --cc=anna-maria@linutronix.de \
    --cc=juri.lelli@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).