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

From	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [patch V2 00/20] timer: Refactor the timer wheel
Date	2016-06-20 17:50 +0200
Message-ID	<rM9Cy-1EU-37@gated-at.bofh.it> (permalink)
References	<rL20p-73O-3@gated-at.bofh.it> <rM99w-1sR-9@gated-at.bofh.it> <rM99w-1sR-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

On Mon, Jun 20, 2016 at 05:13:41PM +0200, Thomas Gleixner wrote:
> On Mon, 20 Jun 2016, Paul E. McKenney wrote:
> 
> > On Fri, Jun 17, 2016 at 01:26:28PM -0000, Thomas Gleixner wrote:
> > > This is the second version of the timer wheel rework series. The first series
> > > can be found here:
> > > 
> > >    http://lkml.kernel.org/r/20160613070440.950649741@linutronix.de
> > > 
> > > The series is also available in git:
> > > 
> > >    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.timers
> > 
> > Ran some longer rcutorture tests, and the scripting complained about
> > hangs.  This turned out to be due to the 12.5% uncertainty, so I fixed
> 
> Is that stuff so sensitive? I'm surprised, because the old slack stuff got you
> 6.25% already.

But didn't you have to ask for slack?

Anyway, rcutorture allows three minutes longer than the duration, and
then kills the test (unless it is actively dumping the ftrace buffer).
A 30-minute test does fine either way, but a 60-minute test gets killed
with high probability.  Changing to hrtimers makes things work nicely
(other than SRCU), even for 60-minute runs.  I have run ten-hour
rcutorture runs with normal completion with the old timers.

Might well be that this switch to hrtimer is needed in some situations
for the old setup.  Given that it happens only once per run, it clearly
has little or no performance downside, so I am queueing it regardless.
Well, I will do so once I take care of the arithmetic limitations that
are causing link-time errors on 32-bit systems.

							Thanx, Paul

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

csiph-web