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Groups > linux.kernel > #1625960

Re: [patch V2 08/10] timer: Implement the hierarchical pull model

From Thomas Gleixner <tglx@linutronix.de>
Newsgroups linux.kernel
Subject Re: [patch V2 08/10] timer: Implement the hierarchical pull model
Date 2017-04-19 11:10 +0200
Message-ID <txTMC-1zl-41@gated-at.bofh.it> (permalink)
References <txEue-8r4-5@gated-at.bofh.it> <txEuf-8r4-41@gated-at.bofh.it> <txT0d-12b-9@gated-at.bofh.it> <txTjA-197-11@gated-at.bofh.it> <txTjA-197-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, 19 Apr 2017, Peter Zijlstra wrote:
> On Wed, Apr 19, 2017 at 10:31:08AM +0200, Thomas Gleixner wrote:
> > On Wed, 19 Apr 2017, Peter Zijlstra wrote:
> > > On Tue, Apr 18, 2017 at 01:11:10PM +0200, Thomas Gleixner wrote:
> 
> > > > +	}
> > > > +	/* Allocate and set up a new group */
> > > > +	group = kzalloc_node(sizeof(*group), GFP_KERNEL, node);
> > > > +	if (!group)
> > > > +		return ERR_PTR(-ENOMEM);
> > > > +
> > > > +	if (!zalloc_cpumask_var_node(&group->cpus, GFP_KERNEL, node)) {
> > > > +		kfree(group);
> > > > +		return ERR_PTR(-ENOMEM);
> > > > +	}
> > > 
> > > So if you place that cpumask last, you can do:
> > > 
> > > 	group = kzalloc_node(sizeof(*group) + cpumask_size(),
> > > 	                     GFP_KERNEL, node);
> > 
> > Hrm, that would allocate extra space for CPUMASK_OFF_STACK=n. I'll have a
> > look.
> > 
> 
> How so? Remember your structure will look like:
> 
> struct group {
> 	/* ... */
> 	unsigned long cpumask[0];
> };
> 
> Which, even for the CPUMASK_OFF_STACK=n case, is exactly 0 bytes of
> total storage.

-ENOTENOUGHCOFFEE

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Thread

[patch V2 00/10] timer: Move from a push remote at enqueue to a pull  at expiry model Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  [patch V2 06/10] timer: Restructure internal locking Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
    Re: [patch V2 06/10] timer: Restructure internal locking Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:10 +0200
  [patch V2 10/10] timer: Always queue timers on the local CPU Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  [patch V2 07/10] tick/sched: Split out jiffies update helper function Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:30 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:30 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:40 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:40 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 10:20 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 10:40 +0200
        Re: [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 11:10 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 10:40 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:00 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:10 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:50 +0200
        Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 12:00 +0200
      Re: [patch V2 08/10] timer: Implement the hierarchical pull model Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 11:50 +0200
        Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 12:00 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 11:30 +0200
    Re: [patch V2 08/10] timer: Implement the hierarchical pull model Peter Zijlstra <peterz@infradead.org> - 2017-04-19 12:30 +0200
  [patch V2 05/10] timer: Retrieve next expiry of pinned/non-pinned  timers seperately Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
    Re: [patch V2 05/10] timer: Retrieve next expiry of  pinned/non-pinned timers seperately Peter Zijlstra <peterz@infradead.org> - 2017-04-19 09:10 +0200
      Re: [patch V2 05/10] timer: Retrieve next expiry of pinned/non-pinned  timers seperately Thomas Gleixner <tglx@linutronix.de> - 2017-04-19 12:00 +0200
  [patch V2 04/10] timer: Keep the pinned timers separate from the  others Thomas Gleixner <tglx@linutronix.de> - 2017-04-18 18:50 +0200
  Re: [patch V2 00/10] timer: Move from a push remote at enqueue to a  pull at expiry model "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-04-21 21:30 +0200

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