From: Richard Cochran <richardcochran@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Jouni Malinen <jkmalinen@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Chris Mason <clm@fb.com>, Arjan van de Ven <arjan@infradead.org>,
rt@linutronix.de, George Spelvin <linux@sciencehorizons.net>,
Len Brown <lenb@kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
Eric Dumazet <edumazet@google.com>
Subject: Re: [patch 4 14/22] timer: Switch to a non cascading wheel
Date: Tue, 16 Aug 2016 09:57:21 +0200 [thread overview]
Message-ID: <20160816075721.GA23077@localhost.localdomain> (raw)
In-Reply-To: <1471024216.32433.5.camel@redhat.com>
On Fri, Aug 12, 2016 at 01:50:16PM -0400, Rik van Riel wrote:
> Could that cause the new timer wheel code to skip over
> timer buckets occasionally, or is this hypothesis bunk?
The new wheel is not different from the old one in this respect. Each
base keeps its own jiffies counter. When returning from a long sleep,
the base counter can be behind the current jiffies value by more than
one. In __run_timers() we loop through all the missed jiffies:
while (time_after_eq(jiffies, base->clk)) {
levels = collect_expired_timers(base, heads);
base->clk++;
while (levels--)
expire_timers(base, heads + levels);
}
So the hypothesis is incorrect.
Thanks,
Richard
next prev parent reply other threads:[~2016-08-16 7:57 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-04 9:50 [patch 4 00/22] timer: Refactor the timer wheel Thomas Gleixner
2016-07-04 9:50 ` [patch 4 01/22] timer: Make pinned a timer property Thomas Gleixner
2016-07-07 8:39 ` [tip:timers/core] timers: Make 'pinned' " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 02/22] x86/apic/uv: Initialize timer as pinned Thomas Gleixner
2016-07-07 8:40 ` [tip:timers/core] timers, x86/apic/uv: Initialize the UV heartbeat " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 03/22] x86/mce: Initialize " Thomas Gleixner
2016-07-07 8:40 ` [tip:timers/core] timers, x86/mce: Initialize MCE restart " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 04/22] cpufreq/powernv: Initialize " Thomas Gleixner
2016-07-07 8:41 ` [tip:timers/core] timers, cpufreq/powernv: Initialize the gpstate " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 05/22] driver/net/ethernet/tile: Initialize " Thomas Gleixner
2016-07-07 8:41 ` [tip:timers/core] timers, driver/net/ethernet/tile: Initialize the egress " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 06/22] drivers/tty/metag_da: Initialize " Thomas Gleixner
2016-07-07 8:42 ` [tip:timers/core] timers, drivers/tty/metag_da: Initialize the poll " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 07/22] drivers/tty/mips_ejtag: Initialize " Thomas Gleixner
2016-07-07 8:42 ` [tip:timers/core] timers, drivers/tty/mips_ejtag: Initialize the poll " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 08/22] net/ipv4/inet: Initialize timers " Thomas Gleixner
2016-07-07 8:43 ` [tip:timers/core] timers, net/ipv4/inet: Initialize connection request " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 09/22] timer: Remove mod_timer_pinned Thomas Gleixner
2016-07-07 8:43 ` [tip:timers/core] timers: Remove the deprecated mod_timer_pinned() API tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 10/22] signal: Use hrtimer for sigtimedwait Thomas Gleixner
2016-07-07 8:43 ` [tip:timers/core] signals: Use hrtimer for sigtimedwait() tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 11/22] hlist: Add hlist_is_singular_node() helper Thomas Gleixner
2016-07-07 8:44 ` [tip:timers/core] " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 12/22] timer: Give a few structs and members proper names Thomas Gleixner
2016-07-07 8:44 ` [tip:timers/core] timers: " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 13/22] timer: Reduce the CPU index space to 256k Thomas Gleixner
2016-07-07 8:45 ` [tip:timers/core] timers: " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 14/22] timer: Switch to a non cascading wheel Thomas Gleixner
2016-07-07 8:45 ` [tip:timers/core] timers: Switch to a non-cascading wheel tip-bot for Thomas Gleixner
2016-08-11 15:21 ` [patch 4 14/22] timer: Switch to a non cascading wheel Jouni Malinen
2016-08-11 20:25 ` [PREEMPT-RT] " rcochran
2016-08-13 9:12 ` Jouni Malinen
2016-08-16 9:46 ` Richard Cochran
2016-08-16 14:35 ` Eric Dumazet
2016-08-17 9:05 ` Jouni Malinen
2016-08-17 9:23 ` rcochran
2016-08-12 17:50 ` Rik van Riel
2016-08-12 19:14 ` Paul E. McKenney
2016-08-16 8:55 ` Richard Cochran
2016-08-16 7:57 ` Richard Cochran [this message]
2016-07-04 9:50 ` [patch 4 15/22] timer: Remove slack leftovers Thomas Gleixner
2016-07-07 8:46 ` [tip:timers/core] timers: Remove set_timer_slack() leftovers tip-bot for Thomas Gleixner
2016-07-22 11:31 ` [patch 4 15/22] timer: Remove slack leftovers Jason A. Donenfeld
2016-07-22 13:04 ` Thomas Gleixner
2016-07-22 15:18 ` Jason A. Donenfeld
2016-07-22 22:54 ` Jason A. Donenfeld
2016-07-04 9:50 ` [patch 4 16/22] timer: Move __run_timers() function Thomas Gleixner
2016-07-07 8:46 ` [tip:timers/core] timers: " tip-bot for Anna-Maria Gleixner
2016-07-04 9:50 ` [patch 4 17/22] timer: Optimize collect timers for NOHZ Thomas Gleixner
2016-07-07 8:47 ` [tip:timers/core] timers: Optimize collect_expired_timers() " tip-bot for Anna-Maria Gleixner
2016-07-04 9:50 ` [patch 4 18/22] tick/sched: Remove pointless empty function Thomas Gleixner
2016-07-07 8:47 ` [tip:timers/core] timers/nohz: Remove pointless tick_nohz_kick_tick() function tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 19/22] timer: Forward wheel clock whenever possible Thomas Gleixner
2016-07-07 8:48 ` [tip:timers/core] timers: Forward the " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 20/22] timer: Only wake softirq if necessary Thomas Gleixner
2016-07-07 8:48 ` [tip:timers/core] timers: " tip-bot for Thomas Gleixner
2016-07-04 9:50 ` [patch 4 21/22] timer: Split out index calculation Thomas Gleixner
2016-07-07 8:48 ` [tip:timers/core] timers: " tip-bot for Anna-Maria Gleixner
2016-07-04 9:50 ` [patch 4 22/22] timer: Optimization for same expiry time in mod_timer() Thomas Gleixner
2016-07-07 8:49 ` [tip:timers/core] timers: Implement optimization " tip-bot for Anna-Maria Gleixner
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