On 06/27/2013 02:24 PM, David Laight wrote:
> It would also increase the latency of CPU-hotunplug operations.
Is that a big deal?
>>>
>>> I thought that was the whole deal with this patchset - making cpu
>>> hotunplugs lighter and faster mostly for powersaving. That said, just
>>> re
> >>> It would also increase the latency of CPU-hotunplug operations.
> >>
> >> Is that a big deal?
> >
> > I thought that was the whole deal with this patchset - making cpu
> > hotunplugs lighter and faster mostly for powersaving. That said, just
> > removing stop_machine call would be a pretty g
On 06/27/2013 03:04 AM, Tejun Heo wrote:
> Hey,
>
> On Wed, Jun 26, 2013 at 11:58:48PM +0530, Srivatsa S. Bhat wrote:
>> Yes, we were discussing hot-unplug latency for use-cases such as
>> suspend/resume. We didn't want to make those operations slower in the
>> process of removing stop_machine() f
Hey,
On Wed, Jun 26, 2013 at 11:58:48PM +0530, Srivatsa S. Bhat wrote:
> Yes, we were discussing hot-unplug latency for use-cases such as
> suspend/resume. We didn't want to make those operations slower in the
> process of removing stop_machine() from hotplug.
Can you please explain why tho? How
On 06/26/2013 10:59 PM, Tejun Heo wrote:
> Hello,
>
> On Wed, Jun 26, 2013 at 11:33:43AM -0400, Steven Rostedt wrote:
>> I thought the whole deal with this patchset was to remove stop_machine
>> from CPU hotplug. Why halt all CPUs just to remove one? stomp_machine()
>> is extremely intrusive for t
On 06/26/2013 08:51 PM, Tejun Heo wrote:
> On Wed, Jun 26, 2013 at 10:51:11AM -0400, Steven Rostedt wrote:
>>> It would also increase the latency of CPU-hotunplug operations.
>>
>> Is that a big deal?
>
> I thought that was the whole deal with this patchset - making cpu
> hotunplugs lighter and fa
On 06/26/2013 07:59 PM, David Laight wrote:
>> Once stop_machine() is gone from the CPU offline path, we won't be able
>> to depend on disabling preemption to prevent CPUs from going offline
>> from under us.
>
> Could you use an rcu-like sequence so that disabling pre-emption
> would be enough?
>
Hello,
On Wed, Jun 26, 2013 at 11:33:43AM -0400, Steven Rostedt wrote:
> I thought the whole deal with this patchset was to remove stop_machine
> from CPU hotplug. Why halt all CPUs just to remove one? stomp_machine()
> is extremely intrusive for the entire system, where as one CPU making
> sure a
On Wed, 2013-06-26 at 08:21 -0700, Tejun Heo wrote:
> On Wed, Jun 26, 2013 at 10:51:11AM -0400, Steven Rostedt wrote:
> > > It would also increase the latency of CPU-hotunplug operations.
> >
> > Is that a big deal?
>
> I thought that was the whole deal with this patchset - making cpu
> hotunplug
On Wed, Jun 26, 2013 at 10:51:11AM -0400, Steven Rostedt wrote:
> > It would also increase the latency of CPU-hotunplug operations.
>
> Is that a big deal?
I thought that was the whole deal with this patchset - making cpu
hotunplugs lighter and faster mostly for powersaving. That said, just
remo
On Wed, 2013-06-26 at 07:34 -0700, Paul E. McKenney wrote:
> On Wed, Jun 26, 2013 at 03:29:40PM +0100, David Laight wrote:
> > > Once stop_machine() is gone from the CPU offline path, we won't be able
> > > to depend on disabling preemption to prevent CPUs from going offline
> > > from under us.
>
On Wed, Jun 26, 2013 at 03:29:40PM +0100, David Laight wrote:
> > Once stop_machine() is gone from the CPU offline path, we won't be able
> > to depend on disabling preemption to prevent CPUs from going offline
> > from under us.
>
> Could you use an rcu-like sequence so that disabling pre-emption
On Wed, Jun 26, 2013 at 07:39:40PM +0530, Srivatsa S. Bhat wrote:
> On 06/26/2013 03:30 AM, Paul E. McKenney wrote:
> > On Wed, Jun 26, 2013 at 01:57:55AM +0530, Srivatsa S. Bhat wrote:
> >> Once stop_machine() is gone from the CPU offline path, we won't be able
> >> to depend on disabling preempti
On Wed, Jun 26, 2013 at 03:29:40PM +0100, David Laight wrote:
> > Once stop_machine() is gone from the CPU offline path, we won't be able
> > to depend on disabling preemption to prevent CPUs from going offline
> > from under us.
>
> Could you use an rcu-like sequence so that disabling pre-emption
> Once stop_machine() is gone from the CPU offline path, we won't be able
> to depend on disabling preemption to prevent CPUs from going offline
> from under us.
Could you use an rcu-like sequence so that disabling pre-emption
would be enough?
Something like rebuilding the cpu list, then forcing
On 06/26/2013 03:30 AM, Paul E. McKenney wrote:
> On Wed, Jun 26, 2013 at 01:57:55AM +0530, Srivatsa S. Bhat wrote:
>> Once stop_machine() is gone from the CPU offline path, we won't be able
>> to depend on disabling preemption to prevent CPUs from going offline
>> from under us.
>>
>> In RCU code,
On Wed, Jun 26, 2013 at 01:57:55AM +0530, Srivatsa S. Bhat wrote:
> Once stop_machine() is gone from the CPU offline path, we won't be able
> to depend on disabling preemption to prevent CPUs from going offline
> from under us.
>
> In RCU code, rcu_implicit_dynticks_qs() checks if a CPU is offline
Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.
In RCU code, rcu_implicit_dynticks_qs() checks if a CPU is offline,
while being protected by a spinlock. Use the get/put_online_cpus_atomic()
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