Re: [patch V2 00/20] timer: Refactor the timer wheel

From	Eric Dumazet <edumazet@google.com>
Newsgroups	linux.kernel
Subject	Re: [patch V2 00/20] timer: Refactor the timer wheel
Date	2016-06-21 04:50 +0200
Message-ID	<rMjVf-8ey-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <rL2jL-7aI-7@gated-at.bofh.it> <rL2tr-7fP-13@gated-at.bofh.it> <rL2Wu-7ET-39@gated-at.bofh.it> <rM7U5-w3-1@gated-at.bofh.it> <rMcK5-3NZ-9@gated-at.bofh.it>
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On Mon, Jun 20, 2016 at 12:03 PM, Rik van Riel <riel@redhat.com> wrote:
> On Mon, 2016-06-20 at 15:56 +0200, Thomas Gleixner wrote:
>>
>> 2) Cut off at 37hrs for HZ=1000. We could make this configurable as a
>> 1000HZ
>>    option so datacenter folks can use this and people who don't care
>> and want
>>    better batching for power can use the 4ms thingy.
>>
>
> It might be easy enough to simply re-queue a timer that
> has not expired yet after 37 hours.
>
> How many 37 hour timers will there be outstanding at any
> one time, that expire around the same time?
>
> Chances are, not many at all. In fact, the vast majority
> of them are likely to be deleted long before they ever
> expire.
>
> Timers lasting longer than 37 hours do not seem like
> something worth optimizing for.
>

I totally agree that these long timers should probably be handled (if
really someone needs them)
using an additional set of helpers able to rearm the timer if it
expires 'too soon'

Thread

[patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:30 +0200
  [patch V2 20/20] timer: Optimization for same expiry time in  mod_timer() Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:30 +0200
  [patch V2 11/20] timer: Give a few structs and members proper names Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:30 +0200
  [patch V2 15/20] timer: Optimize collect timers for NOHZ Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:30 +0200
  [patch V2 19/20] timer: Split out index calculation Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:30 +0200
  [patch V2 06/20] drivers/tty/metag_da: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 01/20] timer: Make pinned a timer property Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 10/20] hlist: Add hlist_is_singular_node() helper Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 04/20] cpufreq/powernv: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 08/20] net/ipv4/inet: Initialize timers as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 03/20] x86/mce: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 17/20] timer: Forward wheel clock whenever possible Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 02/20] x86/apic/uv: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 14/20] timer: Move __run_timers() function Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 12/20] timer: Switch to a non cascading wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
    Re: [patch V2 12/20] timer: Switch to a non cascading wheel "George Spelvin" <linux@sciencehorizons.net> - 2016-06-18 12:00 +0200
  [patch V2 09/20] timer: Remove mod_timer_pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 13/20] timer: Remove slack leftovers Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  [patch V2 05/20] driver/net/ethernet/tile: Initialize timer as pinned Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
    Re: [patch V2 05/20] driver/net/ethernet/tile: Initialize timer as  pinned Peter Zijlstra <peterz@infradead.org> - 2016-06-21 20:50 +0200
  [patch V2 18/20] timer: Only wake softirq if necessary Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 15:40 +0200
  Re: [patch V2 00/20] timer: Refactor the timer wheel Eric Dumazet <edumazet@google.com> - 2016-06-17 15:50 +0200
    Re: [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-17 16:00 +0200
      Re: [patch V2 00/20] timer: Refactor the timer wheel Eric Dumazet <edumazet@google.com> - 2016-06-17 16:30 +0200
        Re: [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-20 16:00 +0200
          Re: [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-20 16:50 +0200
            Re: [patch V2 00/20] timer: Refactor the timer wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-20 18:10 +0200
          Re: [patch V2 00/20] timer: Refactor the timer wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-20 16:50 +0200
          Re: [patch V2 00/20] timer: Refactor the timer wheel Rik van Riel <riel@redhat.com> - 2016-06-20 21:10 +0200
            Re: [patch V2 00/20] timer: Refactor the timer wheel Eric Dumazet <edumazet@google.com> - 2016-06-21 04:50 +0200
  Re: [patch V2 00/20] timer: Refactor the timer wheel Arjan van de Ven <arjanvandeven@gmail.com> - 2016-06-17 16:30 +0200
  Re: [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-20 17:20 +0200
    Re: [patch V2 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-20 17:50 +0200
  Re: [patch V2 00/20] timer: Refactor the timer wheel "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-06-20 17:40 +0200
  Re: [patch V2 00/20] timer: Refactor the timer wheel Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-06-22 09:40 +0200
    Re: [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-22 10:50 +0200
      Re: [patch V2 00/20] timer: Refactor the timer wheel Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-06-22 11:10 +0200
        Re: [patch V2 00/20] timer: Refactor the timer wheel Mike Galbraith <umgwanakikbuti@gmail.com> - 2016-06-22 15:40 +0200
      Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Cyril Hrubis <chrubis@suse.cz> - 2016-06-22 12:40 +0200
        Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-23 10:30 +0200
          Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Cyril Hrubis <chrubis@suse.cz> - 2016-06-23 14:00 +0200
            Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel "George Spelvin" <linux@sciencehorizons.net> - 2016-06-23 16:00 +0200
              Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-23 16:20 +0200
              Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Cyril Hrubis <chrubis@suse.cz> - 2016-06-23 17:20 +0200
                Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Thomas Gleixner <tglx@linutronix.de> - 2016-06-23 17:30 +0200
                Re: [LTP] [patch V2 00/20] timer: Refactor the timer wheel Cyril Hrubis <chrubis@suse.cz> - 2016-06-23 18:40 +0200

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