From: Ingo Molnar <mingo@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.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, Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [patch 13/20] timer: Switch to a non cascading wheel
Date: Tue, 14 Jun 2016 12:11:45 +0200 [thread overview]
Message-ID: <20160614101144.GA849@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1606131426330.5839@nanos>
* Thomas Gleixner <tglx@linutronix.de> wrote:
> On Mon, 13 Jun 2016, Peter Zijlstra wrote:
> > On Mon, Jun 13, 2016 at 08:41:00AM -0000, Thomas Gleixner wrote:
> > > +
> > > + /* Cascading, sigh... */
> >
> > So given that userspace has no influence on timer period; can't we
> > simply fail to support timers longer than 30 minutes?
> >
> > In anything really arming timers _that_ long?
>
> Unfortunately yes. Networking being one of those. Real cascading happens once
> in a blue moon, but it happens.
So I'd really prefer it if we added a few more levels, a hard limit and got rid of
the cascading once and for all!
IMHO 'once in a blue moon' code is much worse than a bit more data overhead.
Thanks,
Ingo
next prev parent reply other threads:[~2016-06-14 10:11 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-13 8:40 [patch 00/20] timer: Refactor the timer wheel Thomas Gleixner
2016-06-13 8:40 ` [patch 01/20] timer: Make pinned a timer property Thomas Gleixner
2016-06-13 8:40 ` [patch 02/20] x86/apic/uv: Initialize timer as pinned Thomas Gleixner
2016-06-13 8:40 ` [patch 03/20] x86/mce: " Thomas Gleixner
2016-06-13 8:40 ` [patch 04/20] cpufreq/powernv: " Thomas Gleixner
2016-06-13 13:18 ` Arjan van de Ven
2016-06-13 8:40 ` [patch 05/20] driver/net/ethernet/tile: " Thomas Gleixner
2016-06-13 8:40 ` [patch 06/20] drivers/tty/metag_da: " Thomas Gleixner
2016-06-13 13:13 ` Arjan van de Ven
2016-06-13 8:40 ` [patch 07/20] drivers/tty/mips_ejtag: " Thomas Gleixner
2016-06-13 8:40 ` [patch 08/20] net/ipv4/inet: Initialize timers " Thomas Gleixner
2016-06-13 8:40 ` [patch 09/20] timer: Remove mod_timer_pinned Thomas Gleixner
2016-06-13 8:40 ` [patch 10/20] timer: Add a cascading tracepoint Thomas Gleixner
2016-06-13 8:40 ` [patch 11/20] hlist: Add hlist_is_last_node() helper Thomas Gleixner
2016-06-13 10:27 ` Paolo Bonzini
2016-06-13 8:40 ` [patch 12/20] timer: Give a few structs and members proper names Thomas Gleixner
2016-06-13 8:41 ` [patch 13/20] timer: Switch to a non cascading wheel Thomas Gleixner
2016-06-13 11:40 ` Peter Zijlstra
2016-06-13 12:30 ` Thomas Gleixner
2016-06-13 12:46 ` Eric Dumazet
2016-06-13 14:30 ` Thomas Gleixner
2016-06-14 10:11 ` Ingo Molnar [this message]
2016-06-14 16:28 ` Thomas Gleixner
2016-06-14 17:14 ` Arjan van de Ven
2016-06-14 18:05 ` Thomas Gleixner
2016-06-14 20:34 ` Peter Zijlstra
2016-06-14 20:42 ` Peter Zijlstra
2016-06-14 21:17 ` Eric Dumazet
2016-06-15 14:53 ` Thomas Gleixner
2016-06-15 14:55 ` Arjan van de Ven
2016-06-15 16:43 ` Thomas Gleixner
2016-06-16 15:43 ` Thomas Gleixner
2016-06-16 16:02 ` Paul E. McKenney
2016-06-16 18:14 ` Peter Zijlstra
2016-06-17 0:40 ` Paul E. McKenney
2016-06-17 4:04 ` Paul E. McKenney
2016-06-16 16:04 ` Arjan van de Ven
2016-06-16 16:09 ` Thomas Gleixner
2016-06-15 15:05 ` Eric Dumazet
2016-06-13 14:36 ` Richard Cochran
2016-06-13 14:39 ` Thomas Gleixner
2016-06-13 8:41 ` [patch 15/20] timer: Move __run_timers() function Thomas Gleixner
2016-06-13 8:41 ` [patch 14/20] timer: Remove slack leftovers Thomas Gleixner
2016-06-13 8:41 ` [patch 16/20] timer: Optimize collect timers for NOHZ Thomas Gleixner
2016-06-13 8:41 ` [patch 17/20] tick/sched: Remove pointless empty function Thomas Gleixner
2016-06-13 8:41 ` [patch 18/20] timer: Forward wheel clock whenever possible Thomas Gleixner
2016-06-13 15:14 ` Richard Cochran
2016-06-13 15:18 ` Thomas Gleixner
2016-06-13 8:41 ` [patch 19/20] timer: Split out index calculation Thomas Gleixner
2016-06-13 8:41 ` [patch 20/20] timer: Optimization for same expiry time in mod_timer() Thomas Gleixner
2016-06-13 14:10 ` [patch 00/20] timer: Refactor the timer wheel Eric Dumazet
2016-06-13 16:15 ` Paul E. McKenney
2016-06-15 15:15 ` Paul E. McKenney
2016-06-15 17:02 ` Thomas Gleixner
2016-06-15 20:26 ` Paul E. McKenney
2016-06-14 8:16 [patch 13/20] timer: Switch to a non cascading wheel George Spelvin
2016-06-14 8:50 ` Thomas Gleixner
2016-06-14 10:15 ` George Spelvin
2016-06-14 10:20 ` Peter Zijlstra
2016-06-14 12:58 ` George Spelvin
2016-06-14 16:48 ` Thomas Gleixner
2016-06-14 19:56 ` George Spelvin
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