linux-kernel - Re: [patch V3 00/22] timer: Refactor the timer wheel

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Message-Id: <20160627235616.GA18544@linux.vnet.ibm.com>
Date:	Mon, 27 Jun 2016 16:56:16 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Chris Mason <clm@...com>,
	Arjan van de Ven <arjan@...radead.org>, rt@...utronix.de,
	Rik van Riel <riel@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	George Spelvin <linux@...encehorizons.net>,
	Len Brown <lenb@...nel.org>,
	Josh Triplett <josh@...htriplett.org>
Subject: Re: [patch V3 00/22] timer: Refactor the timer wheel

On Sun, Jun 26, 2016 at 09:22:36PM -0700, Paul E. McKenney wrote:
> On Fri, Jun 24, 2016 at 02:32:00PM -0000, Thomas Gleixner wrote:
> > This is the third version of the timer wheel rework series. The previous
> > versions can be found here:
> > 
> > V1:   http://lkml.kernel.org/r/20160613070440.950649741@linutronix.de
> > V2:   http://lkml.kernel.org/r/20160617121134.417319325@linutronix.de
> > 
> > The series is also available in git:
> > 
> >    git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP.timers
> > 
> > Changes vs. V2:
> > 
> >  - Removed the 1000Hz granularity reduction to 4ms. Eric explained that
> >    datacenter workloads require the granularity in the first level wheel.
> > 
> >  - Fixed the typo in tilepro. 
> > 
> >  - Converted sigtimedwait() to hrtimers
> > 
> >  - To avoid the cascading I extended the wheel by another level. This removes
> >    the rarely executed cascading code path, but increases the storage size for
> >    HZ>100 slightly. If the tiny folks care, there is an simple option to cut
> >    the storage size in half for the price of reduced granularity.
> > 
> > Thanks,
> 
> And this series avoids the strange SRCU behavior that I saw with the
> last version.  So looks to be getting there!
> 
> I will be torturing it more vigorously, but looking good so far.

And from RCU and rcutorture perspectives:

Tested-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

							Thanx, Paul

> > 	tglx
> > 
> > ----
> >  arch/x86/kernel/apic/x2apic_uv_x.c  |    4 
> >  arch/x86/kernel/cpu/mcheck/mce.c    |    4 
> >  block/genhd.c                       |    5 
> >  drivers/cpufreq/powernv-cpufreq.c   |    5 
> >  drivers/mmc/host/jz4740_mmc.c       |    2 
> >  drivers/net/ethernet/tile/tilepro.c |    4 
> >  drivers/power/bq27xxx_battery.c     |    5 
> >  drivers/tty/metag_da.c              |    4 
> >  drivers/tty/mips_ejtag_fdc.c        |    4 
> >  drivers/usb/host/ohci-hcd.c         |    1 
> >  drivers/usb/host/xhci.c             |    2 
> >  include/linux/list.h                |   10 
> >  include/linux/timer.h               |   34 -
> >  kernel/signal.c                     |   24 
> >  kernel/time/tick-internal.h         |    1 
> >  kernel/time/tick-sched.c            |   46 -
> >  kernel/time/timer.c                 | 1096 +++++++++++++++++++++---------------
> >  lib/random32.c                      |    1 
> >  net/ipv4/inet_connection_sock.c     |    7 
> >  net/ipv4/inet_timewait_sock.c       |    5 
> >  20 files changed, 734 insertions(+), 530 deletions(-)
> > 
> >