From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjanvandeven@gmail.com>,
Ingo Molnar <mingo@kernel.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 22:42:25 +0200 [thread overview]
Message-ID: <20160614204225.GI30154@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.11.1606142000150.5839@nanos>
On Tue, Jun 14, 2016 at 08:05:49PM +0200, Thomas Gleixner wrote:
> On Tue, 14 Jun 2016, Arjan van de Ven wrote:
>
> > evaluating a 120 hours timer ever 37 hours to see if it should fire...
> > not too horrid.
>
> Well that thing is doing weird stuff anyway:
>
> swapper 0 [001] 1789995.305532: timer:timer_start: timer=0xffff8800c8346920 function=death_by_timeout expires=4850639994 [timeout=108000000]
> ssh 3870 [001] 1790025.284704: timer:timer_cancel: timer=0xffff8800c8346920
> ssh 3870 [001] 1790025.284707: timer:timer_start: timer=0xffff8800c8346920 function=death_by_timeout expires=4742722493 [timeout=75000]
> swapper 0 [001] 1790025.330514: timer:timer_cancel: timer=0xffff8800c8346920
> swapper 0 [001] 1790025.330515: timer:timer_start: timer=0xffff8800c8346920 function=death_by_timeout expires=4850647504 [timeout=108000000]
> ssh 3870 [001] 1790055.307058: timer:timer_cancel: timer=0xffff8800c8346920
> ssh 3870 [001] 1790055.307060: timer:timer_start: timer=0xffff8800c8346920 function=death_by_timeout expires=4742730003 [timeout=75000]
> swapper 0 [001] 1790055.352146: timer:timer_cancel: timer=0xffff8800c8346920
>
> And that goes on forever. 2834 such sequences for this particular timer
> instance in 4.5 hours. 90000 sequences total for all timers related to
> death_by_timeout in 4.5 hours
>
> No idea what this is doing and why the heck it nees a 120 hour timeout ....
So it moves that timer on every packet for that TCP connection stream,
provided the expiration is at least 1 second behind.
If the stream hasn't had a packet in 5 days (see previous email), then
the connection state is destroyed.
Its been too long since I've read the TCP RFCs, but I can imagine
changing this will upset people.
next prev parent reply other threads:[~2016-06-14 20:42 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
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 [this message]
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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