Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-14 Thread Christoph Lameter
On Fri, 11 Jul 2014, Peter Zijlstra wrote: > On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote: > > The use case is pretty straightforward because we are trying to keep as > > much OS noise as possible off most processors. Processor 0 is the > > sacrificial lamb that will be used f

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-14 Thread Christoph Lameter
On Fri, 11 Jul 2014, Paul E. McKenney wrote: > > > > I wonder if it's wouldn't be rather reasonable to affine housekeeping to > > all non-nohz-full CPUs > > by default and then people who want finergrained housekeeping can affine > > manually kthreads from userspace. > > > > That implies to bind

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Paul E. McKenney
On Fri, Jul 11, 2014 at 10:45:05PM +0200, Frederic Weisbecker wrote: > On Fri, Jul 11, 2014 at 01:35:13PM -0700, Paul E. McKenney wrote: > > On Fri, Jul 11, 2014 at 09:11:15PM +0200, Frederic Weisbecker wrote: > > > On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote: > > > > On Fri,

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Frederic Weisbecker
On Fri, Jul 11, 2014 at 01:35:13PM -0700, Paul E. McKenney wrote: > On Fri, Jul 11, 2014 at 09:11:15PM +0200, Frederic Weisbecker wrote: > > On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote: > > > On Fri, 11 Jul 2014, Frederic Weisbecker wrote: > > > > > > > > That would imply tha

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Paul E. McKenney
On Fri, Jul 11, 2014 at 09:11:15PM +0200, Frederic Weisbecker wrote: > On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote: > > On Fri, 11 Jul 2014, Frederic Weisbecker wrote: > > > > > > That would imply that all no-nohz processors are housekeeping? So all > > > > processors with a

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Peter Zijlstra
On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote: > The use case is pretty straightforward because we are trying to keep as > much OS noise as possible off most processors. Processor 0 is the > sacrificial lamb that will be used for all OS processing and hopefully all > high latenc

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Frederic Weisbecker
On Fri, Jul 11, 2014 at 12:43:14PM -0700, Paul E. McKenney wrote: > On Fri, Jul 11, 2014 at 09:26:14PM +0200, Frederic Weisbecker wrote: > > On Fri, Jul 11, 2014 at 12:08:16PM -0700, Paul E. McKenney wrote: > > > On Fri, Jul 11, 2014 at 08:57:33PM +0200, Frederic Weisbecker wrote: > > > > On Fri, J

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Paul E. McKenney
On Fri, Jul 11, 2014 at 09:26:14PM +0200, Frederic Weisbecker wrote: > On Fri, Jul 11, 2014 at 12:08:16PM -0700, Paul E. McKenney wrote: > > On Fri, Jul 11, 2014 at 08:57:33PM +0200, Frederic Weisbecker wrote: > > > On Fri, Jul 11, 2014 at 11:45:28AM -0700, Paul E. McKenney wrote: > > > > On Fri, J

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Frederic Weisbecker
On Fri, Jul 11, 2014 at 12:08:16PM -0700, Paul E. McKenney wrote: > On Fri, Jul 11, 2014 at 08:57:33PM +0200, Frederic Weisbecker wrote: > > On Fri, Jul 11, 2014 at 11:45:28AM -0700, Paul E. McKenney wrote: > > > On Fri, Jul 11, 2014 at 08:25:43PM +0200, Frederic Weisbecker wrote: > > > > On Fri, J

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Frederic Weisbecker
On Fri, Jul 11, 2014 at 02:05:08PM -0500, Christoph Lameter wrote: > On Fri, 11 Jul 2014, Frederic Weisbecker wrote: > > > > That would imply that all no-nohz processors are housekeeping? So all > > > processors with a tick are housekeeping? > > > > Well, now that I think about it again, I would r

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Paul E. McKenney
On Fri, Jul 11, 2014 at 08:57:33PM +0200, Frederic Weisbecker wrote: > On Fri, Jul 11, 2014 at 11:45:28AM -0700, Paul E. McKenney wrote: > > On Fri, Jul 11, 2014 at 08:25:43PM +0200, Frederic Weisbecker wrote: > > > On Fri, Jul 11, 2014 at 01:10:41PM -0500, Christoph Lameter wrote: > > > > On Tue,

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Christoph Lameter
On Fri, 11 Jul 2014, Frederic Weisbecker wrote: > > That would imply that all no-nohz processors are housekeeping? So all > > processors with a tick are housekeeping? > > Well, now that I think about it again, I would really like to keep > housekeeping > to CPU 0 when nohz_full= is passed. Yeah.

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Frederic Weisbecker
On Fri, Jul 11, 2014 at 11:45:28AM -0700, Paul E. McKenney wrote: > On Fri, Jul 11, 2014 at 08:25:43PM +0200, Frederic Weisbecker wrote: > > On Fri, Jul 11, 2014 at 01:10:41PM -0500, Christoph Lameter wrote: > > > On Tue, 8 Jul 2014, Frederic Weisbecker wrote: > > > > > > > > I was figuring that a

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Paul E. McKenney
On Fri, Jul 11, 2014 at 08:25:43PM +0200, Frederic Weisbecker wrote: > On Fri, Jul 11, 2014 at 01:10:41PM -0500, Christoph Lameter wrote: > > On Tue, 8 Jul 2014, Frederic Weisbecker wrote: > > > > > > I was figuring that a fair number of the kthreads might eventually > > > > be using this, not jus

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Paul E. McKenney
On Fri, Jul 11, 2014 at 01:10:41PM -0500, Christoph Lameter wrote: > On Tue, 8 Jul 2014, Frederic Weisbecker wrote: > > > > I was figuring that a fair number of the kthreads might eventually > > > be using this, not just for the grace-period kthreads. > > > > Ok makes sense. But can we just rename

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Frederic Weisbecker
On Fri, Jul 11, 2014 at 01:10:41PM -0500, Christoph Lameter wrote: > On Tue, 8 Jul 2014, Frederic Weisbecker wrote: > > > > I was figuring that a fair number of the kthreads might eventually > > > be using this, not just for the grace-period kthreads. > > > > Ok makes sense. But can we just rename

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-11 Thread Christoph Lameter
On Tue, 8 Jul 2014, Frederic Weisbecker wrote: > > I was figuring that a fair number of the kthreads might eventually > > be using this, not just for the grace-period kthreads. > > Ok makes sense. But can we just rename the cpumask to housekeeping_mask? That would imply that all no-nohz processor

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-09 Thread Frederic Weisbecker
On Tue, Jul 08, 2014 at 03:05:56PM -0700, Paul E. McKenney wrote: > Fair point. This would be a kthread_bind_housekeeping(), then. Hmm, after all this should only be needed for kthreads so yeah. > But I need to create an kthread_bind_mask() or some such that acts like > kthread_bind(), but which

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-08 Thread Paul E. McKenney
On Tue, Jul 08, 2014 at 10:40:11PM +0200, Frederic Weisbecker wrote: > On Tue, Jul 08, 2014 at 12:58:37PM -0700, Paul E. McKenney wrote: > > On Tue, Jul 08, 2014 at 08:38:47PM +0200, Frederic Weisbecker wrote: > > > On Tue, Jul 08, 2014 at 08:47:23AM -0700, Paul E. McKenney wrote: > > > > On Tue, J

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-08 Thread Frederic Weisbecker
On Tue, Jul 08, 2014 at 12:58:37PM -0700, Paul E. McKenney wrote: > On Tue, Jul 08, 2014 at 08:38:47PM +0200, Frederic Weisbecker wrote: > > On Tue, Jul 08, 2014 at 08:47:23AM -0700, Paul E. McKenney wrote: > > > On Tue, Jul 08, 2014 at 05:24:00PM +0200, Frederic Weisbecker wrote: > > > > On Mon, J

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-08 Thread Paul E. McKenney
On Tue, Jul 08, 2014 at 08:38:47PM +0200, Frederic Weisbecker wrote: > On Tue, Jul 08, 2014 at 08:47:23AM -0700, Paul E. McKenney wrote: > > On Tue, Jul 08, 2014 at 05:24:00PM +0200, Frederic Weisbecker wrote: > > > On Mon, Jul 07, 2014 at 03:38:15PM -0700, Paul E. McKenney wrote: > > > > From: "Pa

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-08 Thread Frederic Weisbecker
On Tue, Jul 08, 2014 at 08:47:23AM -0700, Paul E. McKenney wrote: > On Tue, Jul 08, 2014 at 05:24:00PM +0200, Frederic Weisbecker wrote: > > On Mon, Jul 07, 2014 at 03:38:15PM -0700, Paul E. McKenney wrote: > > > From: "Paul E. McKenney" > > > > > > Binding the grace-period kthreads to the timeke

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-08 Thread Paul E. McKenney
On Tue, Jul 08, 2014 at 05:24:00PM +0200, Frederic Weisbecker wrote: > On Mon, Jul 07, 2014 at 03:38:15PM -0700, Paul E. McKenney wrote: > > From: "Paul E. McKenney" > > > > Binding the grace-period kthreads to the timekeeping CPU resulted in > > significant performance decreases for some workloa

Re: [PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-08 Thread Frederic Weisbecker
On Mon, Jul 07, 2014 at 03:38:15PM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" > > Binding the grace-period kthreads to the timekeeping CPU resulted in > significant performance decreases for some workloads. For more detail, > see: > > https://lkml.org/lkml/2014/6/3/395 for benchm

[PATCH tip/core/rcu 11/17] rcu: Bind grace-period kthreads to non-NO_HZ_FULL CPUs

2014-07-07 Thread Paul E. McKenney
From: "Paul E. McKenney" Binding the grace-period kthreads to the timekeeping CPU resulted in significant performance decreases for some workloads. For more detail, see: https://lkml.org/lkml/2014/6/3/395 for benchmark numbers https://lkml.org/lkml/2014/6/4/218 for CPU statistics It turns out